Heterosis in maize (Zea mays, L.): characterization of heterotic quantitative trait loci (QTL) for agronomic traits in near isogenic lines (NILs) and their testcrosses

In a previous study on maize (Zea mays, L.) several quantitative trait loci (QTL) showing high dominance-additive ratio for agronomic traits were identified in a population of recombinant inbred lines derived from B73 × H99. For four of these mapped QTL, namely 3.05, 4.10, 7.03 and 10.03 according to their chromosome and bin position, families of near-isogenic lines (NILs) were developed, i.e., couples of homozygous lines nearly identical except for the QTL region that is homozygote either for the allele provided by B73 or by H99. For two of these QTL (3.05 and 4.10) the NILs families were produced in two different genetic backgrounds. The present research was conducted in order to: (i) characterize these QTL by estimating additive and dominance effects; (ii) investigate if these effects can be affected by genetic background, inbreeding level and environmental growing conditions (low vs. high plant density). The six NILs’ families were tested across three years and in three Experiments at different inbreeding levels as NILs per se and their reciprocal crosses (Experiment 1), NILs crossed to related inbreds B73 and H99 (Experiment 2) and NILs crossed to four unrelated inbreds (Experiment 3). Experiment 2 was conducted at two plant densities (4.5 and 9.0 plants m-2). Results of Experiments 1 and 2 confirmed previous findings as to QTL effects, with dominance-additive ratio superior to 1 for several traits, especially for grain yield per plant and its component traits; as a tendency, dominance effects were more pronounced in Experiment 1. The QTL effects were also confirmed in Experiment 3. The interactions involving QTL effects, families and plant density were generally negligible, suggesting a certain stability of the QTL. Results emphasize the importance of dominance effects for these QTL, suggesting that they might deserve further studies, using NILs’ families and their crosses as base materials.

Specific PET-ligands for selected 5-HT and GABA A-receptor subtypes = PET-Liganden mit Spezifität für definierte 5-HT und GABA A-Rezeptor-Subtypen

Für diese Arbeit wurden sechs neue Benzodiazepinderivate, TC07, TC08, TC09, TC10, TC11 und TC12, hergestellt. Diese wurden mittels Radioligandenbindungsassay sowohl auf ihre Bindungseigenschaften für Membranen des Cerebellum, des Hippo-campus und des Cortex der Ratte hin untersucht, als auch für Membranen von HEK293 Zellen, die transient rekombinante GABAA Rezeptoren exprimierten. Zusätz-lich wurden kompetitive in situ Rezeptorautoradiographien an Rattenhirnschnitten mit den Liganden [3H]Ro15-4513 und [3H]R015-1788 durchgeführt. Zusammen ergaben sich aus diesen Experimenten deutliche Hinweise auf eine Selektivität der Verbindun-gen TC07, TC11 und TC12 für a5-Untereinheiten enthaltende GABAA Rezeptoren mit a5-Affinitäten im niedrigen nanomolaren Bereich. In vivo Bindungsexperimente in Ratten, mit [3H]Ro15-1788 als Tracer und TC07 als Kompetitor, ergaben, dass TC07 mehr [3H]Ro15-1788 im Vorderhirn als im Cerebellum verdrängt. Bezog man die regionale Verteilung der a5-Untereinheit des GABAA Rezep-tors im Rattenhirn mit ein – sehr wenige a5-Untereinheiten im Cerebellum, etwa 20 % der GABAA Rezeptor-Untereinheiten im Hippocampus – untermauerten diese Ergeb-nisse die Vermutung, TC07 könne a5-selektiv sein. Diese Daten bestätigten darü-berhinaus, dass TC07 die Blut-Hirn-Schranke passieren kann. Für elektrophysiologische Messungen mit TC07 und TC12 wurden die oben erwähnten transient transfizierten HEK293 Zellen verwendet, welche die GABAA Rezeptor Unte-reinheitenkombination a5b3g2 exprimierten. Das Dosis-Antwort Verhalten ergab keinen signifikanten Effekt für TC12. Die Daten von TC07 dagegen lassen auf einen schwach negativ modulatorischen Effekt schließen, was, zumindest theoretisch, die Möglichkeit eröffnet, TC07 auch als sogenannten cognitive enhancer einzusetzen. Der errechnete Ki-Wert lag in derselben Größenordnung wie der Ki-Wert, der anhand der Bindungsas-saydaten errechnet wurde. Insgesamt rechtfertigen die bisherigen Ergebnisse die radiochemische Markierung mit 18F von drei der sechs getesteten Verbindungen in der Reihenfolge TC07, TC12 und TC11. Des Weiteren wurde [18F]MHMZ, ein potentiell 5-HT2A selektiver Ligand und PET-Tracer einschließlich Vorläufer und Referenzverbindungen, mit hohen Ausbeuten syn-thetisiert (Herth, Debus et al. 2008). Autoradiographieexperimente mit Rattenhirn-schnitten zeigten hervorragende in situ Bindungseigenschaften der neuen Verbindung. Die Daten wiesen eine hohe Selektivität für 5-HT2A Rezeptoren in Verbindung mit einer niedrigen unspezifischen Bindung auf. [18F]MHMZ erfährt in vivo eine schnelle Metabo-lisierung, wobei ein polarer aktiver Metabolit entsteht, welcher vermutlich nicht die Blut-Hirn-Schranke passieren kann. Transversale, sagittale und coronale Kleintier-PET-Bilder des Rattenhirns zeigten eine hohe Anreicherung im frontalen Cortex und im Striatum, während im Cerebellum so gut wie keine Anreicherung festzustellen war. Diese Verteilung deckt sich mit der bekann-ten Verteilung der 5-HT2A Rezeptoren. Die in vivo Anreicherung scheint sich ebenfalls gut mit der Verteilung der in den Autoradiographieexperimenten gemessenen Bindung zu decken. Nach Berechnungen mit dem 4-Parameter Referenzgewebe Modell beträgt das Bindungspotential (BP) für den frontalen Cortex 1,45. Das Cortex zu Cerebellum Verhältnis wurde auf 2,7 nach 30 Minuten Messzeit bestimmt, was bemerkenswert nah an den von Lundkvist et al. für [11C]MDL 100907 publizierten Daten liegt. Abgesehen von der etwas niedrigeren Affinität waren die gemessenen in vitro, in situ und in vivo Daten denen von [3H]MDL 100907 und [11C]MDL 100907 sehr ähnlich, so dass wir ein [18F]Analogon in der Hand haben, das die bessere Selektivität von MDL 100907 verglichen mit Altanserin mit der längeren Halbwertszeit und den besse-ren Eigenschaften für die klinische Routine von 18F verglichen mit 11C verbindet. Die Ergebnisse von [18F]MHMZ rechtfertigenden weitere Experimente, um diesen Liganden für die klinische Routine am Menschen nutzbar zu machen.

Spectroscopic properties from hybrid QM, MM molecular dynamics simulation

The central aim of this thesis work is the application and further development of a hybrid quantum mechanical/molecular mechanics (QM/MM) based approach to compute spectroscopic properties of molecules in complex chemical environments from electronic structure theory. In the framework of this thesis, an existing density functional theory implementation of the QM/MM approach is first used to calculate the nuclear magnetic resonance (NMR) solvent shifts of an adenine molecule in aqueous solution. The findings show that the aqueous solvation with its strongly fluctuating hydrogen bond network leads to specific changes in the NMR resonance lines. Besides the absolute values, also the ordering of the NMR lines changes under the influence of the solvating water molecules. Without the QM/MM scheme, a quantum chemical calculation could have led to an incorrect assignment of these lines. The second part of this thesis describes a methodological improvement of the QM/MM method that is designed for cases in which a covalent chemical bond crosses the QM/MM boundary. The development consists in an automatized protocol to optimize a so-called capping potential that saturates the electronic subsystem in the QM region. The optimization scheme is capable of tuning the parameters in such a way that the deviations of the electronic orbitals between the regular and the truncated (and "capped") molecule are minimized. This in turn results in a considerable improvement of the structural and spectroscopic parameters when computed with the new optimized capping potential within the QM/MM technique. This optimization scheme is applied and benchmarked on the example of truncated carbon-carbon bonds in a set of small test molecules. It turns out that the optimized capping potentials yield an excellent agreement of NMR chemical shifts and protonation energies with respect to the corresponding full molecules. These results are very promising, so that the application to larger biological complexes will significantly improve the reliability of the prediction of the related spectroscopic properties.

On the inheritance and mechanism of baculovirus resistance of the codling moth, Cydia pomonella (L.)

Das Cydia pomonella Granulovirus (CpGV, Baculoviridae) wird seit Ende der 1980er Jahre als hoch-selektives und effizientes biologisches Bekämpfungsmittel zur Kontrolle des Apfelwicklers im Obstanbau eingesetzt. Seit 2004 wurden in Europa verschiedene Apfelwicklerpopulationen beobachtet die resistent gegenüber dem hauptsächlich angewendeten Isolat CpGV-M aufweisen. Die vorliegende Arbeit befasst sich mit der Untersuchung der Vererbung und des Mechanismus der CpGV Resistenz. Einzelpaarkreuzungen zwischen einem empfindlichen Laborstamm (CpS) und einem homogen resistenten Stamm (CpRR1) zeigten, dass die Resistenz durch ein einziges dominantes Gen, das auf dem Z-Chromosom lokalisiert ist, vererbt wird. Massernkreuzungen zwischen CpS und einer heterogen resistenten Feldpopulation (CpR) deuteten zunächst auf einen unvollständig dominanten autosomalen Erbgang hin. Einzelpaarkreuzungen zwischen CpS und CpR bewiesen jedoch, dass die Resistenz in CpR ebenfalls monogen dominant und geschlechtsgebunden auf dem Z-Chromosom vererbt wird. Diese Arbeit diskutiert zudem die Vor- und Nachteile von Einzelpaarkreuzungen gegenüber Massernkreuzungen bei der Untersuchung von Vererbungsmechanismen. Die Wirksamkeit eines neuen CpGV Isolates aus dem Iran (CpGV-I12) gegenüber CpRR1 Larven, wurde in Bioassays getestet. Die Ergebnisse zeigen, dass CpGV-I12 die Resistenz in allen Larvenstadien von CpRR1 brechen kann und fast so gut wirkt wie CpGV-M gegenüber CpS Larven. Daher ist CpGV-I12 für die Kontrolle des Apfelwicklers in Anlagen wo die Resistenz aufgetreten ist geeignet. Um den der CpGV Resistenz zugrunde liegenden Mechanismus zu untersuchen, wurden vier verschiedene Experimente durchgeführt: 1) die peritrophische Membran degradiert indem ein optischer Aufheller dem virus-enthaltenden Futtermedium beigefügt wurde. Das Entfernen dieser mechanischen Schutzbarriere, die den Mitteldarm auskleidet, führte allerdings nicht zu einer Reduzierung der Resistenz in CpR Larven. Demnach ist die peritrophische Membran nicht am Resistenzmechanismus beteiligt. 2) Die Injektion von Budded Virus in das Hämocoel führte nicht zur Brechung der Resistenz. Folglich die die Resistenz nicht auf den Mitteldarm beschränkt, sondern auch in der Sekundärinfektion wirksam. 3) Die Replikation von CpGV in verschiedenen Geweben (Mitteldarm, Hämolymphe und Fettkörper) von CpS und CpRR1 wurde mittels quantitativer PCR verfolgt. In CpS Larven konnte in allen drei Gewebetypen sowohl nach oraler als auch nach intra-hämocoelarer Infektion eine Zunahme der CpGV Genome in Abhängigkeit der Zeit festgestellt werden. Dagegen konnte in den Geweben aus CpRR1 nach oraler sowie intra-hämocoelarer Infektion keine Virusreplikation detektiert werden. Dies deutet darauf hin, dass die CpGV Resistenz in allen Zelltypen präsent ist. 4) Um zu untersuchen ob ein humoraler Faktor in der Hämolymphe ursächlich an der Resistenz beteiligt ist, wurde Hämolymphe aus CpRR1 Larven in CpS Larven injiziert und diese anschließend oral mit CpGV infiziert. Es konnte jedoch keine Immunreaktion beobachtet und kein Faktor in der Hämolymphe identifiziert werden, der Resistenz induzieren könnte. Auf Grundlage dieser Ergebnisse kann festgestellt werden, dass in resistenten Apfelwicklerlarven die virale Replikation in allen Zelltypen verhindert wird, was auf eine Virus-Zell Inkompatibilität hinweist. Da in CpRR1 keine DNA Replikation beobachtet wurde, wird die CpGV Resistenz wahrscheinlich durch eine frühe Unterbindung der Virusreplikation verursacht.Das früh exprimierte Gen pe38 codiert für ein Protein, das wahrscheinlich für die Resistenzbrechung durch CpGV-I12 verantwortlich ist. Interaktionen zwischen dem Protein PE38 und Proteinen in CpRR1 wurden mit Hilfe des Yeast Two-Hybrid (Y2H) Systems untersucht. Die detektierten Interaktionen sind noch nicht durch andere Methoden bestätigt, jedoch wurden zwei mögliche Gene auf dem Z-Chromosom und eines auf Chromosom 15 gefunden, wie möglicherweise an der CpGV Resistenz beteiligt sind.

Between-population outbreeding affects plant defence

Between-population crosses may replenish genetic variation of populations, but may also result in outbreeding depression. Apart from direct effects on plant fitness, these outbreeding effects can also alter plant-herbivore interactions by influencing plant tolerance and resistance to herbivory. We investigated effects of experimental within- and between-population outbreeding on herbivore resistance, tolerance and plant fitness using plants from 13 to 19 Lychnis flos-cuculi populations. We found no evidence for outbreeding depression in resistance reflected by the amount of leaf area consumed. However, herbivore performance was greater when fed on plants from between-population compared to within-population crosses. This can reflect outbreeding depression in resistance and/or outbreeding effects on plant quality for the herbivores. The effects of type of cross on the relationship between herbivore damage and plant fitness varied among populations. This demonstrates how between-population outbreeding effects on tolerance range from outbreeding depression to outbreeding benefits among plant populations. Finally, herbivore damage strengthened the observed outbreeding effects on plant fitness in several populations. These results raise novel considerations on the impact of outbreeding on the joint evolution of resistance and tolerance, and on the evolution of multiple defence strategies.

Sustainable regional development: Reconciling global and local dynamics and stakes in the Swiss Alps

This article explores how global and local dynamics and stakes can be brought together when trying to combine conservation and regional development. For this purpose we analyse a series of studies carried out in the area of the Swiss Alps Jungfrau-Aletsch World Heritage Site (WHS). The approaches used in these studies to analyse the diversity and development of the region included data collection and evaluation of indicators such as population development, number of working places, occupation rates in various economic sectors and commuter balance, as well as interviews with key informants and assessment of existing planning tools. The major challenge of the newly declared World Heritage Region is that it is neither a political or administrative nor a cultural unit but constitutes a completely new type of space that breaks up and crosses traditional boundaries. The studies revealed an economic tertiarisation process and migration of the population from remote areas to regional centres. Tourism was identified as the key economic sector in the region. Regarding regional sustainability, the studies identified a need for quality dialogue and negotiation of interests and stakes. It was shown that in dealing with sustainability at the local level, many key issues cannot be resolved on the ground, as they depend on regional or national decisions, e.g. the conditions for tourism promotion in the region or economic validation of agricultural activity. We conclude from these findings that national or even international factors do not provide a basis for location-specific solutions, as they are often too general, and that the global label does not ensure sustainability in a designated WHS region; this depends entirely on local and regional dynamics.

Evidence of Adaptive Evolutionary Divergence during Biological Invasion

Rapid phenotypic diversification during biological invasions can either arise by adaptation to alternative environments or by adaptive phenotypic plasticity. Where experimental evidence for adaptive plasticity is common, support for evolutionary diversification is rare. Here, we performed a controlled laboratory experiment using full-sib crosses between ecologically divergent threespine stickleback populations to test for a genetic basis of adaptation. Our populations are from two very different habitats, lake and stream, of a recently invaded range in Switzerland and differ in ecologically relevant morphological traits. We found that in a lake-like food treatment lake fish grow faster than stream fish, resembling the difference among wild type individuals. In contrast, in a stream-like food treatment individuals from both populations grow similarly. Our experimental data suggest that genetically determined diversification has occurred within less than 140 years after the arrival of stickleback in our studied region.

Influence of Mechanical and Thermal Boundary Conditions on Stabilizing/Destabilizing Mechanisms in Evaporating Liquid Films

Liquid films, evaporating or non-evaporating, are ubiquitous in nature and technology. The dynamics of evaporating liquid films is a study applicable in several industries such as water recovery, heat exchangers, crystal growth, drug design etc. The theory describing the dynamics of liquid films crosses several fields such as engineering, mathematics, material science, biophysics and volcanology to name a few. Interfacial instabilities typically manifest by the undulation of an interface from a presumed flat state or by the onset of a secondary flow state from a primary quiescent state or both. To study the instabilities affecting liquid films, an evaporating/non-evaporating Newtonian liquid film is subject to a perturbation. Numerical analysis is conducted on configurations of such liquid films being heated on solid surfaces in order to examine the various stabilizing and destabilizing mechanisms that can cause the formation of different convective structures. These convective structures have implications towards heat transfer that occurs via this process. Certain aspects of this research topic have not received attention, as will be obvious from the literature review. Static, horizontal liquid films on solid surfaces are examined for their resistance to long wave type instabilities via linear stability analysis, method of normal modes and finite difference methods. The spatiotemporal evolution equation, available in literature, describing the time evolution of a liquid film heated on a solid surface, is utilized to analyze various stabilizing/destabilizing mechanisms affecting evaporating and non-evaporating liquid films. The impact of these mechanisms on the film stability and structure for both buoyant and non-buoyant films will be examined by the variation of mechanical and thermal boundary conditions. Films evaporating in zero gravity are studied using the evolution equation. It is found that films that are stable to long wave type instabilities in terrestrial gravity are prone to destabilization via long wave instabilities in zero gravity.

Legislative Legacy: Big Changes in Legislative Article of 1972 Constitution -- Jerry Loendorf, Arlyne Reichert & Rich Bechtel “In the Crucible of Change”

The fulcrum upon which were leveraged many of the dramatic progressive changes in Montana that are documented "In the Crucible of Change" series was the lead up to, preparation, writing and adoption of the 1972 Montana Constitution. As Montana citizens exhibited their concern over the dysfunctional state government in MT under its 1889 Constitution, one of the areas that stood out as needing serious change was the Montana Legislature. Meeting for only sixty calendar days every two years, the Legislature regularly tried to carry off the subterfuge of stopping the wall clock at 11:59 PM on the sixtieth day and placing a shroud over it so they could continue to conduct business as if it were still the 60th day. Lawyers hired by the Anaconda Company drafted most bills that legislators wanted to have introduced. Malapportionment, especially in the State Senate where each county had one Senator regardless of their population, created a situation where Petroleum County with 800 residents had one senator while neighboring Yellowstone County with 80,000 people also had one senator -- a 100-1 differential in representation. Reapportionment imposed by rulings of the US Supreme Court in the mid-1960s created great furor in rural Montana to go along with the previous dissatisfaction of the urban centers. Stories of Anaconda Company “thumbs up – thumbs down” control of the votes were prevalent. Committee meeting and votes were done behind closed doors and recorded votes were non-existent except for the nearly meaningless final tally. People were in the dark about the creation of laws that affected their daily lives. It was clear that change in the Legislature had to take the form of change in the Constitution and, because it was not likely that the Legislature would advance Constitutional amendments on the subject, a convention seemed the only remedy. Once that Convention was called and went to work, it became apparent that the Legislative Article provided both opportunity for change and danger that too dramatic a change might sink the whole new document. The activities of the Legislative Committee and the whole Convention when acting upon Legislative issues provides one of the more compelling stories of change. The story of the Legislative Article of the Montana Constitution is discussed in this episode by three major players who were directly involved in the effort: Jerry Loendorf, Arlyne Reichert and Rich Bechtel. Their recollections of the activities surrounding the entire Constitutional Convention and specifically the Legislative Article provide an insider’s perspective of the development of the entire Constitution and the Legislative portion which was of such a high degree of interest to the people of Montana during the important period of progressive change documented “In the Crucible of Change.” Jerry Loendorf, who served as Chair of the Legislative Committee at the 1972 Montana Constitutional Convention, received a BA from Carroll College in 1961 and a JD from the University of Montana Law School in 1964. Upon graduation he served two years as a law clerk for the Montana Supreme Court after which he was for 34 years a partner in the law firm of Harrison, Loendorf & Posten, Duncan. In addition to being a delegate to the Constitutional Convention, Jerry served on the Board of Labor Appeals from 2000 to 2004. He was designated a Montana Special Assistant Attorney General to represent the state in federal court on the challenge to the results of the ratification election of Montana's Constitution in 1972. Jerry served on the Carroll College Board of Directors in the late 1960s and then again as a member of the Board of Trustees of Carroll College from 2001 to 2009. He has served on the Board of Directors of the Rocky Mountain Development Council since 1970 and was on the board of the Helena YMCA from 1981 to 1987. He also served on the board of the Good Samaritan Ministries from 2009 to 2014. On the business side, Jerry was on the Board of Directors of Valley Bank to Helena from 1980 to 2005. He is a member of the American Bar Association, State Bar of Montana, the First Judicial District Bar Association, and the Montana Trial Lawyers Association. Carroll College awarded Jerry the Warren Nelson Award 1994 and the Insignias Award in 2007. At Carroll College, Jerry has funded the following three scholarship endowments: George C and Helen T Loendorf, Gary Turcott, and Fr. William Greytek. Arlyne Reichert, Great Falls Delegate to the Constitutional Convention and former State Legislator, was born in Buffalo, NY in 1926 and attended University of Buffalo in conjunction with Cadet Nurses Training during WWII. She married a Montanan in Great Falls in 1945 and was widowed in 1968. She is mother of five, grandmother of seven, great-grandmother of four. Arlyne was employed by McLaughlin Research Institute in Great Falls for 23 years, serving as Technical Editor of Transplantation Journal in 1967, retiring as Assistant Director in 1989. In addition to being a state legislator (1979 Session) and a delegate to the 1972 Montana Constitutional Convention, she has filled many public roles, including Cascade County Study Commissioner (1974), MT Comprehensive Health Council, US Civil Rights Commission MT Advisory Committee, MT Capitol Restoration Committee, and Great Falls Public Library Trustee. Arlyne has engaged in many non-profit activities including League of Women Voters (State & Local Board Officer – from where her interest in the MT Constitutional change developed), Great Falls Public Radio Association (President & Founder), American Cancer Society (President Great Falls Chapter), Chair of MT Rhodes Scholarship Committee, and Council Member of the National Civic League. She also served a while as a Television Legislative Reporter. Arlyne has been recipient of numerous awards, the National Distinguished Citizens Award from the National Municipal League, two Women of Achievement Awards from Business & Professional Women, the Salute to Women Award by YWCA, Heritage Preservation Award from Cascade County Historical Society and the State of Montana, and the Heroes Award from Humanities Montana. She remains active, serving as Secretary-Treasurer of Preservation Cascade, Inc., and as Board Member of the McLaughlin Research Institute. Her current passion is applied to the preservation/saving of the historic 10th Street Bridge that crosses the Missouri River in Great Falls. Rich Bechtel of Helena was born in Napa, California in 1945 and grew up as an Air Force brat living in such places as Bitberg, Germany, Tripoli, Libya, and Sevilla, Spain. He graduated from Glasgow High School and the University of Montana. Rich was a graduate assistant for noted Montana History professor Professor K. Ross Toole, but dropped out of graduate school to pursue a real life in Montana politics and government. Rich has had a long, varied and colorful career in the public arena. He currently is the Director of the Office of Taxpayer Assistance & Public Outreach for MT’s Department of Revenue. He previously held two positions with the National Wildlife Federation in Washington, DC (Sr. Legislative Representative [1989-91] and Sr. Legislative Representative for Wildlife Policy [2004-2006]). While in Washington DC, he also was Assistant for Senator Lee Metcalf (D-MT), 1974-1976; Federal-State Coordinator for State of Montana, 1976-1989; Director of the Western Governors’ Association Washington Office, 1991-2000; and Director of Federal Affairs for Governor Kitzhaber of Oregon, 2001- 2003. Earlier in Montana Government, between 1971 and 1974, Rich was Research Analyst for MT Blue Ribbon Commission on Postsecondary Education, Legislative Consultant and Bill Drafter for MT Legislative Council, Research Analyst for the MT Constitutional Convention Commission where he provided original research on legislatures, as well as Researcher/Staff for the MT Constitutional Convention Legislative Committee, from where he drafted the various provisions of the Legislative Article and the majority and minority reports on behalf of the Committee members. Rich has represented Montana’s Governor on a trade and cultural mission to Republic of China and participated in US-German Acid Rain Committee sessions in Germany and with European Economic Community environmental officials in Belgium. He is married to Yvonne Seng (Ph.D.) - T’ai Chi apprentice; author and birder.

Regional lymph node staging in prostate cancer: prognostic and therapeutic implications

The role of pelvic lymph node dissection (PLND) in prostate cancer, in which patients and to what extent it should be performed, remains a controversial topic. Preoperative diagnostic methods are more or less unreliable for lymph node staging and PLND remains the most reliable and accurate method. PLND is indicated in all patients with a PSA value >10 ng/ml and in those with a PSA <10 ng/ml if the Gleason score is > or = 7. If PLND is performed then it should always include the tissue along the external iliac vein, in the obturator fossa and on either side of the internal iliac vessels, up to where the ureter crosses the common iliac vessels. In conjunction with RRP extended PLND may increase staging accuracy, influence decision making with respect to adjuvant therapy and possibly impact outcome.

Intergenomic epistasis causes asynchronous hatch times in whitefish hybrids, but only when parental ecotypes differ

Support for the theory of ecological speciation requires evidence for ecological divergence between species which directly or indirectly causes reproductive isolation. This study investigates effects of ecological vs. genetic disparity of parental species on the presence of endogenous selection (deformation and mortality rates) and potential sources of exogenous selection (growth rates and hatch timing) on hybrids. Hybrid embryonic development is analysed in a common-garden full-sib cross of three species belonging to two different ecotypes within the Coregonus lavaretus species flock in the central Alpine region of Europe. Although hatch timing was similar across the three species, embryonic growth rates and egg sizes differed between ecotypes. This led to a mismatch between embryonic growth rate and egg size in hybrid crosses that reveals epistasis between the maternal and embryonic genomes and transgressive hatch times that were asynchronous with control crosses. A strong constraint of egg size to embryo size at late development was also evident. We argue that this demonstrates potential for coadaptation of a maternal trait (egg size) with offspring growth rate to be an important source of selection against hybridization between ecotypes with different egg sizes. Implications for the measurement and quantification of early life-history traits affected by this additive relationship, such as hatch day and larval size, are also discussed.

Asymmetric Effects of Loss and Gain of a Floral Trait on Pollinator Preference

Shifts in pollination syndromes involve coordinated changes in multiple floral traits. This raises the question of how plants can cope with rapid changes in pollinator availability by the slow process of accumulation of mutations in multiple genes. Here we study the transition from bee to hawkmoth pollination in the genus Petunia. Interspecific crosses followed by single locus introgressions were used to recreate putative intermediate evolutionary stages in the evolution of moth pollination. The effect of the loss/gain of petal color was asymmetric: it had no influence on the established pollinator but enhanced visitation by the new pollinator. Therefore, shifts in pollination syndromes may proceed through intermediate stages of reduced specialization and consequently enhanced reproductive assurance. The loss of petal color in moth-pollinated Petunia involves null mutations in a single regulatory gene, An2. Such simple genetic changes may be sufficiently rapid and frequent to ensure survival during pollinator failure.

Behavioural isolation may facilitate homoploid hybrid speciation in cichlid fish

Hybrid speciation is constrained by the homogenizing effects of gene flow from the parental species. In the absence of post-mating isolation due to structural changes in the genome, or temporal or spatial premating isolation, another form of reproductive isolation would be needed for homoploid hybrid speciation to occur. Here, we investigate the potential of behavioural mate choice to generate assortative mating among hybrids and parental species. We made three-first-generation hybrid crosses between different species of African cichlid fish. In three-way mate-choice experiments, we allowed hybrid and nonhybrid females to mate with either hybrid or nonhybrid males. We found that hybrids generally mated nonrandomly and that hybridization can lead to the expression of new combinations of traits and preferences that behaviourally isolate hybrids from both parental species. Specifically, we find that the phenotypic distinctiveness of hybrids predicts the symmetry and extent of their reproductive isolation. Our data suggest that behavioural mate choice among hybrids may facilitate the establishment of isolated hybrid populations, even in proximity to one or both parental species.

Genetically controlled variation of "acid" beta-galactosidase detected in Rattus norvegicus by isoelectric focusing.

Two genetically variant forms of rat "acid" beta-galactosidase were found to differ in isoelectric point and pH dependence, but not in thermostability or sensitivity to inhibition by p-mercuribenzoate (PMB). The results of two backcrosses and an intercross indicated that the isoelectric focusing phenotypes are controlled by two codominant alleles at a single autosomal locus, for which we propose the name Glb-1. No significant linkage between Glb-1 and albino (LG I), brown (LG II), or hooded (LG VI) was observed. Strain-specific differences in total levels of kidney beta-galactosidase were detected, but it is not yet known whether the variation is controlled by genes linked to Glb-1. Experiments in which organ homogenates were incubated with neuraminidase indicated that the genetically variant forms do not result from differences in sialylation, though sialylation does appear to be largely responsible for the presence of multiple bands within each phenotype and for differences in the banding patterns of beta-galactosidases derived from different organs. The beta-galactosidase present in the bands used for Glb-1 typing resembles human GM1 gangliosidase (GLB1) with respect to pH optimum, substrate specificity, and susceptibility to inhibition by PMB. It also appears that Glb-1 is homologous with the Bgl-e locus of the mouse. In rats as in mice the genetically variant bands of beta-galactosidase are active at acid pH and have relatively high isoelectric points. In both species these bands are readily detectable in kidney homogenates, and can be revealed in homogenates of liver or spleen following treatment with neuraminidase. The presence of the same beta-galactosidase bands in homogenates of rat kidney and small intestine as well as in neuraminidase-treated homogenates of liver and spleen suggests that the Glb-1 variants differ by one or more point mutations in the structural gene for "acid" beta-galactosidase.

Parentage analysis with genetic markers in natural populations. I. The expected proportion of offspring with unambiguous paternity.

Recent studies indicate that polymorphic genetic markers are potentially helpful in resolving genealogical relationships among individuals in a natural population. Genetic data provide opportunities for paternity exclusion when genotypic incompatibilities are observed among individuals, and the present investigation examines the resolving power of genetic markers in unambiguous positive determination of paternity. Under the assumption that the mother for each offspring in a population is unambiguously known, an analytical expression for the fraction of males excluded from paternity is derived for the case where males and females may be derived from two different gene pools. This theoretical formulation can also be used to predict the fraction of births for each of which all but one male can be excluded from paternity. We show that even when the average probability of exclusion approaches unity, a substantial fraction of births yield equivocal mother-father-offspring determinations. The number of loci needed to increase the frequency of unambiguous determinations to a high level is beyond the scope of current electrophoretic studies in most species. Applications of this theory to electrophoretic data on Chamaelirium luteum (L.) shows that in 2255 offspring derived from 273 males and 70 females, only 57 triplets could be unequivocally determined with eight polymorphic protein loci, even though the average combined exclusionary power of these loci was 73%. The distribution of potentially compatible male parents, based on multilocus genotypes, was reasonably well predicted from the allele frequency data available for these loci. We demonstrate that genetic paternity analysis in natural populations cannot be reliably based on exclusionary principles alone. In order to measure the reproductive contributions of individuals in natural populations, more elaborate likelihood principles must be deployed.