Molecular mechanisms controlling the precision of chemokine guided cell migration

By the end of the first day of embryonic development, zebrafish primordial germ cells (PGCs) arrive at the site where the gonad develops. In our study we investigated the mechanisms controlling the precision of primordial germ cell arrival at their target. We found that in contrast with our expectations which were based on findings in Drosophila and mouse, the endoderm does not constitute a preferred migration substrate for the PGCs. Rather, endoderm derivatives are important for later stages of organogenesis keeping the PGC clusters separated. It would be interesting to investigate the precise mechanism by which endoderm controls germ cell position in the gonad. In their migration towards the gonad, zebrafish germ cells follow the gradient of chemokine SDF-1a, which they detect using the receptor CXCR4b that is expressed on their membrane. Here we show that the C-terminal region of CXCR4b is responsible for down-regulation of receptor activity as well as for receptor internalization. We demonstrate that receptor molecules unable to internalize are less potent in guiding germ cells to the site where the gonad develops, thereby implicating chemokine receptor internalization in facilitating precision of migration during chemotaxis in vivo. We demonstrate that while CXCR4b activity positively regulates the duration of the active migration phases, the down-regulation of CXCR4b signalling by internalization limits the duration of this phase. This way, receptor signalling contributes to the persistence of germ cell migration, whereas receptor down-regulation enables the cells to stop and correct their migration path close to the target where germ cells encounter the highest chemokine signal. Chemokine receptors are involved in directing cell migration in different processes such as lymphocyte trafficking, cancer and in the development of the vascular system. The C-terminal domain of many chemokine receptors was shown to be essential for controlling receptor signalling and internalization. It would therefore be important to determine whether the role for receptor internalization in vivo as described here (allowing periodical corrections to the migration route) and the mechanisms involved (reducing the level of signalling) apply for those other events, too.

Migratory route of Strongyloides venezuelensis in Lewis rats: Comparison of histological analyses and PCR

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A molecular phylogeny for the Tribe Dacini (Diptera: Tephritidae) : systematic and biogeographic implications

With well over 700 species, the Tribe Dacini is one of the most species-rich clades within the dipteran family Tephritidae, the true fruit flies. Nearly all Dacini belong to one of two very large genera, Dacus Fabricius and Bactrocera Macquart. The distribution of the genera overlap in or around the Indian subcontinent, but the greatest diversity of Dacus is in Africa and the greatest diversity of Bactrocera is in south-east Asia and the Pacific. The monophyly of these two genera has not been rigorously established, with previous phylogenies only including a small number of species and always heavily biased to one genus over the other. Moreover, the subgeneric taxonomy within both genera is complex and the monophyly of many subgenera has not been explicitly tested. Previous hypotheses about the biogeography of the Dacini based on morphological reviews and current distributions of taxa have invoked an out-of-India hypothesis; however this has not been tested in a phylogenetic framework. We attempted to resolve these issues with a dated, molecular phylogeny of 125 Dacini species generated using 16S, COI, COII and white eye genes. The phylogeny shows that Bactrocera is not monophyletic, but rather consists of two major clades: Bactrocera s.s. and the ‘Zeugodacus group of subgenera’ (a recognised, but informal taxonomic grouping of 15 Bactrocera subgenera). This ‘Zeugodacus’ clade is the sister group to Dacus, not Bactrocera and, based on current distributions, split from Dacus before that genus moved into Africa. We recommend that taxonomic consideration be given to raising Zeugodacus to genus level. Supportive of predictions following from the out-of-India hypothesis, the first common ancestor of the Dacini arose in the mid-Cretaceous approximately 80 mya. Major divergence events occurred during the Indian rafting period and diversification of Bactrocera apparently did not begin until after India docked with Eurasia (50–35 mya). In contrast, diversification in Dacus, at approximately 65 mya, apparently began much earlier than predicted by the out-of-India hypothesis, suggesting that, if the Dacini arose on the Indian plate, then ancestral Dacus may have left the plate in the mid to late Cretaceous via the well documented India–Madagascar–Africa migration route. We conclude that the phylogeny does not disprove the predictions of an out-of-India hypothesis for the Dacini, although modification of the original hypothesis is required.

Biodegradação dos óleos e sua relação com as fácies sedimentares da região do Anhembi

Este trabalho consistiu em aprimorar o entendimento da rota de migração do óleo no reservatório e verificar a possibilidade de variação da intensidade da biodegradação com as heterogeneidades existentes. Foram utilizadas como base para a dissertação sete amostras coletadas na bacia sedimentar do Paraná, no arenito asfáltico do Anhembi, afloramento da Fazenda Betumita. A Fazenda Betumita é considerada a ocorrência mais expressiva de óleo na região do alto estrutural do Anhembi, apresentando a maior acumulação de arenito asfáltico na borda leste da Bacia do Paraná. A ocorrência dos arenitos asfálticos na área de estudo é predominantemente por arenitos da Formação Pirambóia. Estes arenitos foram preenchidos por hidrocarbonetos relacionados ao sistema Irati-Pirambóia e são caracterizados como imaturo, devido ausência de n-alcanos e abundância de esteranos e terpanos. As amostras coletadas foram analisadas através da cromatografia líquida e gasosa e correlacionadas com a descrição das fácies do afloramento. A biodegradação do óleo apresentou a tendência de aumentar do topo para a base do afloramento, local caracterizado por fácies subaquosas, onde se encontra o contato óleo/água, propício para o crescimento dos microorganismos degradadoras de óleo. Na fácie de interduna, a biodegradação foi menor, pois este ambiente é caracterizado por partículas argilo-minerais e menores permo-porosidade, não propício para o crescimento de microorganismos capazes de degradar o óleo. Foi observada a presença de diasteranos e 25-norhopanos nas amostras coletadas, indicando que o óleo do afloramento está severamente biodegradado. Os esteranos apresentaram maior biodegradação na base do afloramento onde está o contato óleo/água e maior reposição de oxigênio pela infiltração de água meteórica, tornando-se ambiente propício para crescimento das bactérias aeróbicas tendendo a degradar preferencialmente os esteranos. Entretanto os hopanos apresentaram maior biodegradação no topo do afloramento, local com condições propícias para o crescimento das bactérias anaeróbicas, que tenderam a degradar preferencialmente os hopanos. As informações adquiridas nesta pesquisa são de grande relevância para o conhecimento na exploração do petróleo, pois geralmente esses conhecimentos não estão disponíveis nos dados de subsuperfície. Este trabalho servirá de parâmetro para o planejamento da produção e recuperação secundária e terciária de reservatórios com fácies sedimentares semelhantes da área estudada.

Evolutionary history of the mtDNA 9-bp deletion in Chinese populations and its relevance to the peopling of east and southeast Asia

In total, 1218 Chinese from twelve ethnic groups and nine Han geographic groups were screened for the mtDNA 9-bp deletion motif. The frequency of the 9-bp deletion in all samples was 14.7% but ranged from 0% to 32% in the various ethnic groups. Three individuals had a triplication of the 9-bp segment. Phylogenetic and demographic analyses of the mtDNA hypervariable segment 1 (HVS1) sequences suggest that the 9-bp deletion occurred more than once in China. The majority of the Chinese deletion:haplotypes (about 90%) have a common origin as a mutational event following an initial expansion of modem humans in eastern Asia. Other deletion haplotypes and the three haplotypes with a 9-bp triplication may have arisen independently in the Chinese, presumably by replication error. HVS1 haplotype analysis suggests two possible migration routes of the 9-bp deletion in east and southeast Asia. Both migrations originated in China with one route leading to the Pacific Islands via Taiwan, the other to southeast Asia and possibly the Nicobar Islands. Along both routes of peopling, a decrease in HVS1 diversity of the mtDNA haplotypes is observed. The "Polynesian motif (16217T/C, 16247A/G, and 16261C/T)" and the 16140T/C, 16266C/A, or C/G polymorphisms appear specific to each migration route.

A new Pennsylvanian Oriocrassatellinae from Brazil and the distribution of the genus Oriocrassatella in space and time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A new Pennsylvanian Oriocrassatellinae from Brazil and the distribution of the genus Oriocrassatella in space and time

Oriocrassatella Etheridge Jr., 1907 is a long range crassatellid bivalve genus well recognized in shallow waters of epeiric seas throughout the upper part of Paleozoic. The first occurrences of this genus are recorded in the sedimentary successions of the Gondwana, both in Australia and South America. However, the geographic and age distribution of Oriocrassatella in Late Mississippian deposits of Australia and Argentina may indicate an earliest Visean or even a pre-Visean origin for the genus. Following its origin in Early Carboniferous a complex paleobiogeographic history from Southern to Northern Hemisphere took place in the Permian. During its initial dispersal phase from Late Carboniferous to the Early Permian the genus thrived in cold water environments associated to the Late Paleozoic Gondwana glaciation. Shallow-water bottoms of the warm waters of the central Gondwana fringe and Laurussia were colonized by Oriocrassatella only during Early Permian times when the genus became cosmopolitan. A new species of this genus is described herein, Oriocrassatella piauiensis n. sp., recorded from the Piaui Formation, Pennsylvanian of the Parnaiba Basin. This new species may represent an early adaptation to warm waters. However, based on available data, species of this genus seem to have adapted definitely to warm water environments probably related the Late Pennsylvanian interglacial phases. In these phases, climatic barrier were interrupted allowing the faunal interchange and larval dispersion following a South to North migration route through the eastern margins of Gondwana and the eastern Paleotethys.

Gateway--Gateway National Recreation Area, New York-New Jersey /

"*GPO:2011--365-615/80606 Reprint 2011."

The molecular mechanisms utilised by mesenchymal stem cells in migration to acute myocardial infarction

Heart damage caused by acute myocardial infarction (AMI) is a leading cause of death and disability in Australia. Novel therapies are still required for the treatment of this condition due to the poor reparative ability of the heart. As such, cellular therapies that assist in the recovery of heart muscle are of great current interest. Culture expanded mesenchymal stem cells (MSC) represent a stem and progenitor cell population that has been shown to promote tissue recovery in pre-clinical studies of AMI. For MSC-based therapies in the clinic, an intravenous route of administration would ideally be used due to the low cost, ease of delivery and relative safety. The study of MSC migration is therefore clinically relevant for a minimally invasive cell therapy to promote regeneration of damaged tissue. C57BL/6, UBI-GFP-BL/6 and CD44-/-/GFP+/+ mice were utilised to investigate mMSC migration. To assist in murine models of MSC migration, a novel method was used for the isolation of murine MSC (mMSC). These mMSC were then expanded in culture and putative mMSC were positive for Sca-1, CD90.2, and CD44 and were negative for CD45 and CD11b. Furthermore, mMSC from C57BL/6 and UBI-GFP-BL/6 mice were shown to differentiate into cells of the mesodermal lineage. Cells from CD44-/-/GFP+/+ mice were positive for Sca-1 and CD90.2, and negative for CD44, CD45 and CD11b however, these cells were unable to differentiate into adipocytes and chondrocytes and express lineage specific genes, PLIN and ACAN. Analysis of mMSC chemokine receptor (CR) expression showed that although mMSC do express chemokine receptors, (including those specific for chemokines released after AMI), these were low or undetectable by mRNA. However, protein expression could be detected, which was predominantly cytoplasmic. It was further shown that in both healthy (unperturbed) and inflamed tissues, mMSC had very little specific migration and engraftment after intravenous injection. To determine if poor mMSC migration was due to the inability of mMSC to respond to chemotactic stimuli, chemokine expression in bone marrow, skin injury and hearts (healthy and after AMI) was analysed at various time points by quantitative real-time PCR (qRT PCR). Many chemokines were up-regulated after skin biopsy and AMI, but the highest acute levels were found for CXCL12 and CCL7. Due to their high expression in infarcted hearts, the chemokines CXCL12 and CCL7 were tested for their effect on mMSC migration. Despite CR expression at both protein and mRNA levels, migration in response to CXCL12 and CCL7 was low in mMSC cultured on Nunclon plastic. A novel tissue culture plastic technology (UpCellTM) was then used that allowed gentle non-enzymatic dissociation of mMSC, thus preserving surface expression of the CRs. Despite this the in vitro data indicated that CXCL12 fails to induce significant migration ability of mMSC, while CCL7 induces significant, but low-level migration. We speculated this may be because of low levels of surface expression of chemokine receptors. In a strategy to increase cell surface expression of mMSC chemokine receptors and enhance their in vitro and in vivo migration capacity, mMSC were pre-treated with pro-inflammatory cytokines. Increased levels of both mRNA and surface protein expression were found for CRs by pre-treating mMSC with pro-inflammatory cytokines including TNF-á, IFN-ã, IL-1á and IL-6. Furthermore, the chemotactic response of mMSC to CXCL12 and CCL7 was significantly higher with these pretreated cells. Finally, the effectiveness of this type of cell manipulation was demonstrated in vivo, where mMSC pre-treated with TNF-á and IFN-ã showed significantly increased migration in skin injury and AMI models. Therefore this thesis has demonstrated, using in vitro and in vivo models, the potential for prior manipulation of MSC as a possible means for increasing the utility of intravenously delivery for MSC-based cellular therapies.

Deterministic nanoassembly : Neutral or plasma route?

It is shown that, owing to selective delivery of ionic and neutral building blocks directly from the ionized gas phase and via surface migration, plasma environments offer a better deal of deterministic synthesis of ordered nanoassemblies compared to thermal chemical vapor deposition. The results of hybrid Monte Carlo (gas phase) and adatom self-organization (surface) simulation suggest that higher aspect ratios and better size and pattern uniformity of carbon nanotip microemitters can be achieved via the plasma route. © 2006 American Institute of Physics.

Structure and optical properties of Cd-substituted ZnO (Zn1-xCdxO) nanostructures synthesized by the high-pressure solution route

We report the synthesis of Cd-substituted ZnO nanostructures (Zn1-xCdxO with x up to approximate to 0.09) by the high-pressure solution growth method. The synthesized nanostructures comprise nanocrystals that are both particles (similar to 10-15 nm) and rods which grow along the [002] direction as established by transmission electron microscope (TEM) and x-ray diffraction (XRD) analysis. Rietveld analysis of the XRD data shows a monotonic increase of the unit cell volume with the increase of Cd concentration. The optical absorption, as well as the photoluminescence (PL), shows a red shift on Cd substitution. The line width of the PL spectrum is related to the strain inhomogeneity and it peaks in the region where the CdO phase separates from the Zn1-xCdxO nanostructures. The time-resolved photoemission showed a long-lived (similar to 10 ns) component. We propose that the PL behaviour of the Zn1-xCdxO is dominated by strain in the sample with the red shift of the PL linked to the expansion of the unit cell volume on Cd substitution.

Implication of a sigma-Methane Complex en Route to Elimination of Methane from a Ruthenium Complex: An Experimental and Theoretical Investigation

The five-coordinated 16-electron complex Ru(Me)(dppe)(2)]OTf] (3) undergoes methane elimination at room temperature to afford the ortho-metalated species (dppe){(C6H5)(C6H4)PCH2CH2P(C6H5)(2)}Ru]OTf] (7). Methane elimination, monitored using NMR spectroscopy, revealed no intermediate throughout the reaction. The NOE between Ru-Me protons and ortho phenyl protons and an agostic interaction trans to the methyl group were found in complex 3 by NMR spectroscopy, which form the basis for three plausible pathways for methane elimination and ortho metalation: pathway I (through spatial interaction), pathway II (through oxidative addition and reductive elimination), and pathway III (through agostic interaction). Methane elimination from complex 3 via pathway I was discounted, since it involves interactions through space and not through bonds. Moreover, the calculated energy barrier for the pathway I transition state was quite high (71.3 kcal/mol), which also indicates that this pathway is very unlikely. Furthermore, no spectroscopic evidence for oxidatively added seven-coordinated Ru(IV) species was found and the computed energy barrier of the transition state for pathway II was moderately high (41.1 kcal/mol), which suggests that this cannot be the right pathway for methane elimination and ortho-metalation of complex 3. On the other hand, indirect evidence in the form of chemical reactions point to the most plausible pathway for methane elimination, pathway III, via the intermediacy of a sigma-CH4 complex that could not be found spectroscopically. DFT calculations at several levels on this pathway showed an initial low-barrier rearrangement through TS1 to a square-pyramidal intermediate wherein methyl and agostic C-H are cis to each other. Migration of hydrogen from agostic C-H and elimination of methane proceed through the transition state TS2, which retains a weak metal-H bonding through most parts of the reaction coordinate. Upon comparison of all three pathways, pathway III was found to be the most likely for methane elimination and ortho-metalation of complex 3.

Global distribution of Y-chromosome haplogroup C reveals the prehistoric migration routes of African exodus and early settlement in East Asia

The regional distribution of an ancient Y-chromosome haplogroup C-M130 (Hg C) in Asia provides an ideal tool of dissecting prehistoric migration events. We identified 465 Hg C individuals out of 4284 males from 140 East and Southeast Asian populations. We genotyped these Hg C individuals using 12 Y-chromosome biallelic markers and 8 commonly used Y-short tandem repeats (Y-STRs), and performed phylogeographic analysis in combination with the published data. The results show that most of the Hg C subhaplogroups have distinct geographical distribution and have undergone long-time isolation, although Hg C individuals are distributed widely across Eurasia. Furthermore, a general south-to-north and east-to-west cline of Y-STR diversity is observed with the highest diversity in Southeast Asia. The phylogeographic distribution pattern of Hg C supports a single coastal 'Out-of-Africa' route by way of the Indian subcontinent, which eventually led to the early settlement of modern humans in mainland Southeast Asia. The northward expansion of Hg C in East Asia started similar to 40 thousand of years ago (KYA) along the coastline of mainland China and reached Siberia similar to 15 KYA and finally made its way to the Americas. Journal of Human Genetics (2010) 55, 428-435; doi:10.1038/jhg.2010.40; published online 7 May 2010

Abundance, migration and management of Jatka (juvenile hilsa, Tenualosa ilisha) in the Gajner Beel, Pabna, Bangladesh

Studies on the abundance, migration and management of Jatka (juvenile hilsa, Tenualosa ilisha) were conducted in the Gajner Beel, located at the south-east corner of the Pabna Irrigation and Rural Development Project (PIRDP) in Sujanagar Upazila of Pabna district, Bangladesh. The main Jatka season was found to be extended from mid August to mid October. Veshal/Bandh/Khora Jal (lift net) and Ber Jal (beach seine net) were found as the major gears involved in Jatka fishing. The estimated total amount of Jatka caught from the Beel during the studied season was 46.2 t. The migratory route of Jatka is extended from the Padma and/or Jamuna rivers to the Badai river and then to the Beel through the sluice gate. The possibility of breeding of hilsa in the Beel was nullified. Finally, a community based management plan was suggested for implementation by the Gajner Beel management committee.

Observation and theoretical analysis for the sand-waves migration in the North Gulf of South China Sea

According to the environmental characteristic of the north gulf of South China Sea, a quasi-3D mechanics model has been built for simulating the small scale sand-waves migration in the seas of southwest of Hainan Island. Based on the submarine micro-geomorphic data induced by multi-beam system and hydrographic survey record, the migrations of the sand-waves in the study area are predicted. The results show that calculation is consistent with the observation data in the groove of sand ridge, but not well in the crest of sand ridge. It is indicated that the mechanics model should be used to predict the migration of the small scale sand-waves which are dominated by bed load in the seas. This paper is very meaningful to project the route of submarine pipeline.