The tetracycline resistance gene tet39 is present in both Gram-negative and Gram-positive bacteria from a polluted river, Southwestern Nigeria

Aim:  Previous analysis of tet39 suggests it may be present in other bacterial species. Hence, we investigated the host range of tet39 among bacterial from a poultry waste polluted river in Southwestern Nigeria.
Methods and Results:  Thirteen resistant bacterial isolated from the water and sediment of the polluted river was investigated for the presence of tetracycline resistance genes tetA , tetB , tetC , tet39 and the transposon integrase gene of the Tn916/1545 family by PCR. While tetA , tetB , tetC and integrase genes cannot be detected in any of the organisms, tet39 was detected in eight of the tested organisms including three Gram-positive species. Sequence analysis showed the genes have high sequence identities (≥99%) with tet39 of Acinetobacter sp. LUH5605, the first and only bacterial genus from which the gene has been reported to date. This is a novel observation.
Conclusions:  This study shows that apart from Acinetobacter , tet39 is present in other bacterial species tested in this study.
Significance and Impact of the Study:  This study adds to available information on the occurrence and distribution of tet39 among environmental bacteria and suggests that the gene has a broader host range than previously reported.     

The impacts of changes in vegetation cover on dry season flow in the Kikuletwa River, northern Tanzania

While the decrease in flow is obvious in the Kikuletwa River, the mechanism leading to the decrease is unclear. We assessed the influence of vegetation cover change on dry season flow in the Kikuletwa River. The combined cover of closed and open forests decreased by 68% while closed and open forests decreased by 56% and 64% respectively. Land under agroforestry decreased by 25%, while that under annual crops increased by 41%. Grasslands increased by 116% and riverine vegetation decreased by 53%. Daily dry season flow showed a slightly decreasing trend in one of the stations despite all of them receiving water from the Rundugai natural springs. On the other hand, low flow indices indicated no statistically significant changes in the long-term average flow and there was no identifiable change in the rainfall amount. The majority (93%) of the local people perceived a changing rainfall pattern and decline in dry season flow in the Kikuletwa River. Changes in the dry season flow then can be associated with the identified land cover changes. Further research to substantiate the local people perceptions is important as indigenous knowledge may be good evidence for ascertaining changes in the natural environment.     

Leptin accelerates pronuclear formation following intracytoplasmic sperm injection of porcine oocytes: Possible role for MAP kinase inactivation

Leptin, a multifunctional hormone, is present in mammalian oocytes and follicular fluids and cumulus cells. While leptin modulates oocyte maturation in vitro which seems to result in enhancement of embryo development, it is unclear whether leptin treatment of oocytes affects cytoplasmic maturation and fertilization processes. In order to gain a better understanding of the role of leptin during oocyte maturation, we examined microtubule and microfilament assembly following oocyte maturation and blastocyst formation, mitogen-activated protein kinase (MAPK) activity, and pronuclear formation following parthenogenetic stimuli or intracytoplasmic sperm injection (ICSI) in leptin-treated oocytes. Addition of 10 or 100 ng/ml leptin during oocyte maturation did not increase the proportion of metaphase II oocytes, but enhanced development to blastocyst stage by day 7 (P < 0.01) after parthenogenetic activation (PA), accompanied by increased cell number. However there was no effect on the number of apoptotic cells in blastocysts. Following maturation in the presence of leptin, there were more oocytes with normal spindle formation. MAPK activity decreased more rapidly, and pronuclear formation was accelerated after parthenogenetic activation or ICSI of leptin-treated oocytes. These results suggested that exogeneous leptin enhanced spindle assembly and accelerated pronuclear formation following fertilization, possibly via the MAPK pathway.     

Metabolism and Plant Hormone Action During Clubroot Disease

Infection of Brassicaceae with the obligate biotrophic pathogen Plasmodiophora brassicae results in the development of root galls (clubroots). During the transformation of a healthy root to a root gall a plethora of changes in primary and secondary metabolism occur. The upper part of an infected plant is retarded in growth due to redirection of assimilates from the shoot to the root. In addition, changes in the levels of plant growth regulators, especially auxins and cytokinins, contribute to the hypertrophy of infected roots. Also, defense reactions are manipulated after inoculation of suitable host plants with P. brassicae. This review summarizes our current knowledge on the changes in these parameters. A model is presented for how primary metabolism and secondary metabolism, including plant hormones, interact to induce clubroot formation.     

Chondrogenesis,joint formation,and articular cartilage regeneration

The repair of joint surface defects remains a clinical challenge, as articular cartilage has a limited healing response. Despite this, articular cartilage does have the capacity to grow and remodel extensively during pre‐ and post‐natal development. As such, the elucidation of developmental mechanisms, particularly those in post‐natal animals, may shed valuable light on processes that could be harnessed to develop novel approaches for articular cartilage tissue engineering and/or regeneration to treat injuries or degeneration in adult joints. Much has been learned through mouse genetics regarding the embryonic development of joints. This knowledge, as well as the less extensive available information regarding post‐natal joint development is reviewed here and discussed in relation to their possible relevance to future directions in cartilage tissue repair and regeneration. J. Cell. Biochem. 107: 383–392, 2009. © 2009 Wiley‐Liss, Inc.     

Wetlands and global climate change: the role of wetland restoration in a changing world

Global climate change is recognized as a threat to species survival and the health of natural systems. Scientists worldwide are looking at the ecological and hydrological impacts resulting from climate change. Climate change will make future efforts to restore and manage wetlands more complex. Wetland systems are vulnerable to changes in quantity and quality of their water supply, and it is expected that climate change will have a pronounced effect on wetlands through alterations in hydrological regimes with great global variability. Wetland habitat responses to climate change and the implications for restoration will be realized differently on a regional and mega-watershed level, making it important to recognize that specific restoration and management plans will require examination by habitat. Floodplains, mangroves, seagrasses, saltmarshes, arctic wetlands, peatlands, freshwater marshes and forests are very diverse habitats, with different stressors and hence different management and restoration techniques are needed. The Sundarban (Bangladesh and India), Mekong river delta (Vietnam), and southern Ontario (Canada) are examples of major wetland complexes where the effects of climate change are evolving in different ways. Thus, successful long term restoration and management of these systems will hinge on how we choose to respond to the effects of climate change. How will we choose priorities for restoration and research? Will enough water be available to rehabilitate currently damaged, water-starved wetland ecosystems? This is a policy paper originally produced at the request of the Ramsar Convention on Wetlands and incorporates opinion, interpretation and scientific-based arguments.     

Increasing chiral recognition in acetal formation

The design of substituted lactols is described, which in their reaction with racemic alkyl aryl carbinols react preferentially with one of the enantiomers exhibiting selectivities up to 14:1.     

Multiple stimulations for muscle–nerve–blood vessel unit in compensatory hypertrophied skeletal muscle of rat surgical ablation model

Tissue inflammation and multiple cellular responses in the compensatory enlarged plantaris (OP Plt) muscle induced by surgical ablation of synergistic muscles (soleus and gastrocnemius) were followed over 10 weeks after surgery. Contralateral surgery was performed in adult Wistar male rats. Cellular responses in muscle fibers, blood vessels and nerve fibers were analyzed by immunohistochemistry and electron microscopy. Severe muscle fiber damage and disappearance of capillaries associated with apparent tissue edema were observed in the peripheral portion of OP Plt muscles during the first week, whereas central portions were relatively preserved. Marked cell activation/proliferation was also mainly observed in peripheral portions. Similarly, activated myogenic cells were seen not only inside but also outside of muscle fibers. The former were likely satellite cells and the latter may be interstitial myogenic cells. One week after surgery, small muscle fibers, small arteries and capillaries and several branched-muscle fibers were evident in the periphery, thus indicating new muscle fiber and blood vessel formation. Proliferating cells were also detected in the nerve bundles in the Schwann cell position. These results indicate that the compensatory stimulated/enlarged muscle is a suitable model for analyzing multiple physiological cellular responses in muscle–nerve–blood vessel units under continuous stretch stimulation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Voting patterns and alliance formation in the European Parliament

Members of the European Parliament (MEPs) have voluntarily formed transnational political groups and invariably follow the voting instructions of these groups. This is intriguing as there are few obvious incentives for doing so. Unlike national parties, for example, the political groups in the European Parliament are not punished by the electorate if they are divided on key issues, as citizens know very little about what goes on inside the European Parliament. This paper pieces together an explanation of why the European political groups exist and why they have become so powerful by looking at the determinants of group cohesion and by undertaking a spatial analysis of voting in the European Parliament. MEPs who share preferences on a range of issues on the European Union policy agenda have an incentive to establish a division-of-labour contract and to share the costs of collecting information. Once internal party policy specialization and agenda setting has been established, MEPs have incentives to follow the voting instructions of their group owing to the advantages of cohesion in a context of repeated voting.