Phenyl-Ring-Bearing Cationic Surfactants: Effect of Ring Location on the Micellar Structure

A series of isomeric cationic surfactants (S1-S5) bearing a long alkyl chain that carries a 1,4-phenylene unit and a trimethyl ammonium headgroup was synthesized; the location of the phenyl ring within the alkyl tail was varied in an effort to understand its influence on the amphiphilic properties of the surfactants. The cmc's of the surfactants were estimated using ionic conductivity measurements and isothermal calorimetric titrations (ITC); the values obtained by the two methods were found to be in excellent agreement. The ITC measurements provided additional insight into the various thermodynamic parameters associated with the micellization process. Although all five surfactants have exactly the same molecular formula, their micellar properties were seen to vary dramatically depending on the location of the phenyl ring; the cmc was seen to decrease by almost an order of magnitude when the phenyl ring was moved from the tail end (cmc of S1 is 23 mM) to the headgroup region (cmc of S5 is 3 mM). In all cases, the enthalpy of micellization was negative but the entropy of micellization was positive, suggesting that in all of these systems the formation of micelles is both enthalpically and entropically favored. As expected, the decrease in cmc values upon moving the phenyl ring from the tail end to he headgroup region is accompanied by an increase in the thermodynamic driving force (Delta G) for micellization. To understand further the differences in the micellar structure of these surfactants, small-angle neutron scattering (SANS) measurements were carried out; these measurements reveal that the aggregation number of the micelles increases as the cmc decreases. This increase in the aggregation number is also accompanied by an increase in the asphericity of the micellar aggregate and a decrease in the fractional charge. Geometric packing arguments are presented to account for these changes in aggregation behavior as a function of phenyl ring location.

Dexamethasone negatively regulates phenobarbitone-activated transcription but synergistically enhances cytoplasmic levels of cytochrome P-450b/e messenger RNA

Dexamethasone has a potentiating effect on phenobarbitone mediated induction of cytochrome P-450b + e mRNAs in adult rat liver. However, the glucocorticoid inhibits phenobarbitone-activated transcription of cytochrome P-450b + e mRNAs by 60-70%. This inhibitory effect is evident in run-off transcription of the endogenous genes as well as in the transcription of an added cloned gene fragment. Dexamethasone inhibits the phenobarbitone-mediated increase in the binding of a transcription factor(s) to the upstream region of the gene as evidenced by gel retardation and Southwestern blot analysis. The glucocorticoid does not stabilize the phenobarbitone-induced polyribosomal cytochrome P-450b + e mRNAs but appears to stabilize the nuclear transcripts. It is proposed that a negative element may mediate the action of dexamethasone at the level of nuclear transcription and stabilization of the nuclear transcript may account for the potentiating effect of the glucocorticoid on phenobarbitone-mediated increase in cytochrome P-450b + e mRNAs in the cytoplasm of the adult rat liver. However, the cytochrome P-450b protein levels are slightly lower in phenobarbitone + dexamethasone treatment than in phenobarbitone-treated liver microsomes.

"But we are dong it!" Ghanalaisen Hon kunnan naisvaltuutettujen työssään kohtaamat haasteet

Tässä tutkielmassa kuvataan tekijöitä, jotka haittaavat naisten toimintaa kunnanvaltuutettuina tehokkaalla tai naisten itsensä haluamalla tavalla sekä vaikuttavat heidän mahdollisuuksiinsa vaikuttaa päätöksentekoon Ghanan paikallishallinnossa. Tutkimuksessa analysoidaan sekä paikallishallintoon nimitettyjen että vaaleilla valittujen naisten asemaa valtuutettuina, mitä aiemmissa tutkimuksissa Ghanan paikallishallinnosta ei ole tehty. Ghanassa nimittäin 30 prosenttia kunnanvaltuutetuista nimitetään tehtäväänsä. Lopulta tutkimuksessa analysoidaan nimitettyjen ja vaaleilla valittujen naisvaltuutettujen mahdollisuuksia edustaa halutessaan naisten intressejä. Hon kunnanvaltuuston tapaus oli erittäin kiinnostava, sillä vuonna 2006 naisten osuus kunnanvaltuutetuista nousi 35,7 prosenttiin. Aiemmin naisia oli ollut valtuustossa huomattavasti vähemmän. Tutkimusta varten tehtiin kenttätyötä Ghanassa. Tutkimus perustuu 16 Hon kunnanvaltuutetun haastatteluun ja kunnan pormestarin kanssa käytyyn keskusteluun. Kartoitan Hon kunnanvaltuuston naisvaltuutettujen toimintaan vaikuttavia tekijöitä ja naisedustajien työssä kohtaamia esteitä sekä naisvaltuutettujen omien kokemusten että miespuolisten kunnanvaltuutettujen näkemysten kautta. Tutkimustulokset osoittivat, että naisvaltuutetut kohtasivat työssään monia haasteita. Moni esteistä oli yhdistettävissä toimimattomiin rakenteisiin, miehisiin normeihin ja käytäntöihin sekä toisaalta naisten miehiä huonompaan sosiaaliseen asemaan. Esimerkiksi liikkuminen vaalialueella ja jopa kokouksiin saapuminen olijoillekin naisille suuri haaste. Myös paikallisten ihmisten vaatimukset saada henkilökohtaista rahallista hyötyä valtuutetuilta nousivat esiin naisten esteenä. Toisaalta näkemysten esittäminen kokouksissa vaikutti naisille ongelmalliselta eli huomio kiinnittyi naisten poliittiseen kokemattomuuteen sekä valtuuston institutionaaliseen kulttuuriin. Nimitettyjen naisten asema kunnanvaltuustossa paljastui erilaiseksi kuin vaaleilla valittujen naisedustajien. Nimitettyjen edustajien järjestelmä, jota on perusteltu mahdollisuutena lisätä naisten intressien edustusta paikallishallinnossa, näyttäytyi tutkimusten tulosten perusteella kyseenalaisena keinona lisätä naisten edustusta paikallishallinnossa. Nimitettyjä valtuutettuja ei esimerkiksi nähty legitiimeinä ihmisten edustajina paikallishallinnossa vaan heidän katsottiin edistävän puolueensa intressejä, ei paikallisten ihmisten. Nimitettyjen edustajien järjestelmä myös paljastui paikalliselle poliittiselle eliitille suosiolliseksi järjestelmäksi valita kiintiön kautta edustajiksi itselleen, ei paikallisille ihmisille tai paikallisille naisille, sopivia edustajia.

Protection of adult but not newborn mice against lethal intracerebral challenge with Japanese encephalitis virus by adoptively transferred virus-specific cytotoxic T lymphocytes: Requirement for L3T4(+) T cells

The protective ability of cytotoxic T cells (CTL) raised in vitro against Japanese encephalitis virus (JEV) was examined by adoptive transfer experiments. Adoptive transfer of anti-JEV effecters by intracerebral (i.c.) but not by intraperitoneal (i.p.) or intravenous (i.v.) routes protected adult BALB/c mice against lethal i.c. JEV challenge. In contrast to adult mice, adoptive transfer of anti-JEV effecters into newborn (4-day-old) and suckling (8-14-day-old) mice did not confer protection. However, virus-induced death was delayed in suckling mice compared to newborn mice upon adoptive transfer. The specific reasons for lack of protection in newborn mice are not clear but virus load was found to be higher in newborn mice brains compared to those of adults and virus clearance was observed only in adult mice brains but not in newborn mice brains upon adoptive transfer. Specific depletion of Lyt 2.2(+), L3T4(+) or Thy-1(+) T cell populations before adoptive transfer abrogated the protective ability of transferred effecters. However, when Lyt 2.2(+) cell-depleted and L3T4(+) cell-depleted effecters were mixed and transferred into adult mice the protective activity was retained, demonstrating that both Lyt 2.2(+) and L3T4(+) T cells are necessary to confer protection. Although the presence of L3T4(+) T cells in adoptively transferred effector populations enhanced virus-specific serum neutralizing antibodies, the presence of neutralizing antibodies alone without Lyt 2.2(+) cells was not sufficient to confer protection.

Mycobacterium leprae RecA is structurally analogous but functionally distinct from Mycobacterium tuberculosis RecA protein

Mycobacterium leprae is closely related to Mycobacterium tuberculosis, yet causes a very different illness. Detailed genomic comparison between these two species of mycobacteria reveals that the decaying M. leprae genome contains less than half of the M. tuberculosis functional genes. The reduction of genome size and accumulation of pseudogenes in the M. leprae genome is thought to result from multiple recombination events between related repetitive sequences, which provided the impetus to investigate the recombination-like activities of RecA protein. In this study, we have cloned, over-expressed and purified M. leprae RecA and compared its activities with that of M. tuberculosis RecA. Both proteins, despite being 91% identical at the amino acid level, exhibit strikingly different binding profiles for single-stranded DNA with varying GC contents, in the ability to catalyze the formation of D-loops and to promote DNA strand exchange. The kinetics and the extent of single-stranded DNA-dependent ATPase and coprotease activities were nearly equivalent between these two recombinases. However, the degree of inhibition exerted by a range of ATP:ADP ratios was greater on strand exchange promoted by M. leprae RecA compared to its M. tuberculosis counterpart. Taken together, our results provide insights into the mechanistic aspects of homologous recombination and coprotease activity promoted by M. lepare RecA, and further suggests that it differs from the M. tuberculosis counterpart. These results are consistent with an emerging concept of DNA-sequence influenced structural differences in RecA nucleoprotein filaments and how these differences reflect on the multiple activities associated with RecA protein. (C) 2011 Elsevier B.V. All rights reserved.

Males, but not females, mate with multiple partners: a laboratory study of a primitively eusocial wasp Ropalidia marginata

The intense interest in social Hymenoptera, on account of their elaborate sociality and the paradox of altruism, has often suffered from considerable gender imbalance. This is partly due to the fact that worker behaviour and altruism are restricted to the females and partly because males often live off the nest. Yet, understanding the males, especially in the context of mating biology is essential even for understanding the evolution of sociality. Mating patterns have a direct bearing on the levels of intra-colony genetic relatedness, which in turn, along with the associated costs and benefits of worker behaviour, are central to our understanding of the evolution of sociality. Although mating takes place away from the nest in natural colonies of the primitively eusocial wasp Ropalidia marginata, mating can be observed in the laboratory if a male and a female are placed in a transparent, aerated plastic container, and both wasps are in the range of 5-20 days of age. Here, we use this setup and show that males, but not females, mate serially with multiple partners. The multiple mating behaviour of the males is not surprising because in nature males have to mate with a number of females, only a few of whom will go on to lay eggs. The reluctance of R. marginata females to mate with multiple partners is consistent with the expectation of monogamy in primitively eusocial species with totipotent females, although the apparent discrepancy with a previous work with allozyme markers in natural colonies suggesting that females may sometimes mate with two or three different males remains to be resolved.

Females of a tree cricket prefer larger males but not the lower frequency male calls that indicate large body size

In the tree cricket Oecanthus henryi, females are attracted by male calls and can choose between males. To make a case for female choice based on male calls, it is necessary to examine male call variation in the field and identify repeatable call features that are reliable indicators of male size or symmetry. Female preference for these reliable call features and the underlying assumption behind this choice, female preference for larger males, also need to be examined. We found that females did prefer larger males during mating, as revealed by the longer mating durations and longer spermatophore retention times. We then examined the correlation between acoustic and morphological features and the repeatability of male calls in the field across two temporal scales, within and across nights. We found that carrier frequency was a reliable indicator of male size, with larger males calling at lower frequencies at a given temperature. Simultaneous playback of male calls differing in frequency, spanning the entire range of natural variation at a given temperature, revealed a lack of female preference for low carrier frequencies. The contrasting results between the phonotaxis and mating experiments may be because females are incapable of discriminating small differences in frequency or because the change in call carrier frequency with temperature renders this cue unreliable in tree crickets. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

The zinc finger proteins Mxr1p and repressor of phosphoenolpyruvate carboxykinase (ROP) have the same DNA binding specificity but regulate Methanol Metabolism antagonistically in pichia pastoris

The methanol-inducible alcohol oxidase I (AOXI) promoter of the methylotrophic yeast, Pichia pastoris, is used widely for the production of recombinant proteins. AOXI transcription is regulated by the zinc finger protein Mxr1p (methanol expression regulator 1). ROP (repressor of phosphoenolpyruvate carboxykinase, PEPCK) is a methanol- and biotin starvation-inducible zinc finger protein that acts as a negative regulator of PEPCK in P. pastoris cultured in biotin-deficient, glucose-ammonium medium. The function of ROP during methanol metabolism is not known. In this study, we demonstrate that ROP represses methanol-inducible expression of AOXI when P. pastoris is cultured in a nutrient-rich medium containing yeast extract, peptone, and methanol (YPM). Deletion of the gene encoding ROP results in enhanced expression of AOXI and growth promotion whereas overexpression of ROP results in repression of AOXI and growth retardation of P. pastoris cultured in YPM medium. Surprisingly, deletion or overexpression of ROP has no effect on AOXI gene expression and growth of P. pastoris cultured in a minimal medium containing yeast nitrogen base and methanol (YNBM). Subcellular localization studies indicate that ROP translocates from cytosol to nucleus of cells cultured in YPM but not YNBM. In vitro DNA binding studies indicate that AOXI promoter sequences containing 5' CYCCNY 3' motifs serve as binding sites for Mxr1p as well as ROP. Thus, Mxr1p and ROP exhibit the same DNA binding specificity but regulate methanol metabolism antagonistically in P. pastoris. This is the first report on the identification of a transcriptional repressor of methanol metabolism in any yeast species.

Perfect Static Balance of Linkages by Addition of Springs But Not Auxiliary Bodies

A linkage of rigid bodies under gravity loads can be statically counter-balanced by adding compensating gravity loads. Similarly, gravity loads or spring loads can be counterbalanced by adding springs. In the current literature, among the techniques that add springs, some achieve perfect static balance while others achieve only approximate balance. Further, all of them add auxiliary bodies to the linkage in addition to springs. We present a perfect static balancing technique that adds only springs but not auxiliary bodies, in contrast to the existing techniques. This technique can counter-balance both gravity loads and spring loads. The technique requires that every joint that connects two bodies in the linkage be either a revolute joint or a spherical joint. Apart from this, the linkage can have any number of bodies connected in any manner. In order to achieve perfect balance, this technique requires that all the spring loads have the feature of zero-free-length, as is the case with the existing techniques. This requirement is neither impractical nor restrictive since the feature can be practically incorporated into any normal spring either by modifying the spring or by adding another spring in parallel. DOI: 10.1115/1.4006521]

SpecNet: Spectrum Sensing Sans Frontieres

While the under-utilization of licensed spectrum based on measurement studies conducted in a few developed countries has spurred lots of interest in opportunistic spectrum access, there exists no infrastructure today for measuring real-time spectrum occupancy across vast geographical regions. In this paper, we present the design and implementation of SpecNet, a first-of-its-kind platform that allows spectrum analyzers around the world to be networked and efficiently used in a coordinated manner for spectrum measurement as well as implementa- tion and evaluation of distributed sensing applications. We demonstrate the value of SpecNet through three applications: 1) remote spectrum measurement, 2) primary transmitter coverage estimation and 3) Spectrum-Cop that quickly identifies and localizes transmitters in a frequency range and geographic region of interest.

Antimony-resistant but not antimony-sensitive Leishmania donovani up-regulates host IL-10 to overexpress multidrug-resistant protein 1

The molecular mechanism of antimony-resistant Leishmania donovani ((SbLD)-L-R)-driven up-regulation of IL-10 and multidrug-resistant protein 1 (MDR1) in infected macrophages (M phi s) has been investigated. This study showed that both promastigote and amastigote forms of (SbLD)-L-R, but not the antimony-sensitive form of LD, express a unique glycan with N-acetylgalactosamine as a terminal sugar. Removal of it either by enzyme treatment or by knocking down the relevant enzyme, galactosyltransferase in (SbLD)-L-R (KD (SbLD)-L-R), compromises the ability to induce the above effects. Infection of M phi s with KD (SbLD)-L-R enhanced the sensitivity toward antimonials compared with infection with (SbLD)-L-R, and infection of BALB/c mice with KD (SbLD)-L-R caused significantly less organ parasite burden compared with infection induced by (SbLD)-L-R. The innate immune receptor, Toll-like receptor 2/6 heterodimer, is exploited by (SbLD)-L-R to activate ERK and nuclear translocation of NF-kappa B involving p50/c-Rel leading to IL-10 induction, whereas MDR1 up-regulation is mediated by PI3K/Akt and the JNK pathway. Interestingly both recombinant IL-10 and (SbLD)-L-R up-regulate MDR1 in M. with different time kinetics, where phosphorylation of PI3K was noted at 12 h and 48 h, respectively, but M phi s derived from IL-10(-/-) mice are unable to show MDR1 up-regulation on infection with (SbLD)-L-R. Thus, it is very likely that an IL-10 surge is a prerequisite for MDR1 up-regulation. The transcription factor important for IL-10-driven MDR1 up-regulation is c-Fos/c-Jun and not NF-kappa B, as evident from studies with pharmacological inhibitors and promoter mapping with deletion constructs.

Virgin wasps develop ovaries on par with mated females, but lay fewer eggs

In the primitively eusocial wasp Ropalidia marginata, mating is not necessary for a female wasp to develop her ovaries, lay eggs, and even to become the sole egg layer of her colony despite the presence of other mated nestmates. Here, we show that virgin wasps do not differ from their mated counterparts in the extent and rapidity of their ovarian development, in the proportion of individuals that build a nest and laid eggs, and in the time taken to do so. However, a significantly larger proportion of virgin females showed resorbing oocytes, and laid fewer eggs as compared to mated individuals. Thus, virgin females have the ability to develop ovaries and lay eggs but also to refrain from necessarily laying all mature eggs produced, before mating opportunities arise. This dual ability would be adaptive in haplodiploid, tropical species with perennial nesting cycles and frequent opportunities for workers to become replacement queens or solitary nest foundresses throughout the year.

N-Terminal disordered domain of saccharomyces cerevisiae Hop1 protein Is dispensable for DNA binding, bridging, and synapsis of double-stranded DNA molecules but is ecessary for spore formation

The cytological architecture of the synaptonemal complex (SC), a meiosis-specific proteinaceous structure, is evolutionarily conserved among eukaryotes. However, little is known about the biochemical properties of SC components or the mechanisms underlying their roles in meiotic chromosome synapsis and recombination. Functional analysis of Saccharomyces cerevisiae Hop1, a key structural component of SC, has begun to reveal important insights into its function in interhomolog recombination. Previously, we showed that Hop1 is a structure-specific DNA-binding protein, exhibits higher binding affinity for the Holliday junction, and induces structural distortion at the core of the junction. Furthermore, Hop1 promotes DNA condensation and intra- and intermolecular synapsis between duplex DNA molecules. Here, we show that Hop1 possesses a modular domain organization, consisting of an intrinsically disordered N-terminal domain and a protease-resistant C-terminal domain (Hop1CTD). Furthermore, we found that Hop1CTD exhibits strong homotypic as well as heterotypic protein protein interactions, and its biochemical activities were similar to those of the full-length Hop1 protein. However, Hop1CTD failed to complement the meiotic recombination defects of the Delta hop1 strain, indicating that both N- and C-terminal domains of Hop1 are essential for meiosis and spore formation. Altogether, our findings reveal novel insights into the structure-function relationships of Hop1 and help to further our understanding of its role in meiotic chromosome synapsis and recombination.