mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Hoxd10 induction and regionalization in the developing lumbosacral spinal cord

We have used Hoxd10 expression as a primary marker of the lumbosacral region to examine the early programming of regional characteristics within the posterior spinal cord of the chick embryo. Hoxd10 is uniquely expressed at a high level in the lumbosacral cord, from the earliest stages of motor column formation through stages of motoneuron axon outgrowth. To define the time period when this gene pattern is determined, we assessed Hoxd10 expression after transposition of lumbosacral and thoracic segments at early neural tube stages. We present evidence that there is an early prepattern for Hoxd10 expression in the lumbosacral neural tube; a prepattern that is established at or before stages of neural tube closure. Cells within more posterior lumbosacral segments have a greater ability to develop high level Hoxd10 expression than the most anterior lumbosacral segments or thoracic segments. During subsequent neural tube stages, this prepattern is amplified and stabilized by environmental signals such that all lumbosacral segments acquire the ability to develop high levels of Hoxd10, independent of their axial environment. Results from experiments in which posterior neural segments and/or paraxial mesoderm segments were placed at different axial levels suggest that signals setting Hoxd10 expression form a decreasing posterior-to-anterior gradient. Our experiments do not, however, implicate adjacent paraxial mesoderm as the only source of graded signals. We suggest, instead, that signals from more posterior embryonic regions influence Hoxd10 expression after the early establishment of a regional prepattern. Concurrent analyses of patterns of LIM proteins and motor column organization after experimental surgeries suggest that the programming of these characteristics follows similar rules.     

Determinants of cardiac Na(+)/Ca(2+) exchanger temperature dependence: NH(2)-terminal transmembrane segments

The cardiacNa⁺/Ca²⁺ exchanger (NCX) in troutexhibits profoundly lower temperature sensitivity in comparison to themammalian NCX. In this study, we attempt to characterize the regions of the NCX molecule that are responsible for its temperature sensitivity. Chimeric NCX molecules were constructed using wild-type trout andcanine NCX cDNA and expressed in Xenopus oocytes.NCX-mediated currents were measured at 7, 14, and 30°C using thegiant excised-patch technique. By using this approach, the differentialtemperature dependence of NCX was found to reside within theNH₂-terminal region of the molecule. Specifically, we foundthat ~75% of the Na⁺/Ca²⁺ exchangedifferential energy of activation is attributable to sequencedifferences in the region that include the first four transmembranesegments, and the remainder is attributable to transmembrane segmentfive and the exchanger inhibitory peptide site.

     

Genetic diversity of north Okhotsk Sea chum salmon populations with natural and artificial reproduction

The variability of 32 enzyme loci was studied in chum salmon populations with different types of reproduction—natural, mixed, and artificial—in some Magadan Region rivers. Among the populations studied, the values of mean heterozygosity and allele number per locus did not differ significantly. We found evidence of definite temporal stability of the populations, and also found that their genetic variability was expressed only slightly but still remained in spite of periodic egg transplantations between rivers. Statistically significant spatial genetic differentiation of the populations accounted for 0.55 to 0.76% of the total variation and the mean inter-year differentiation accounted for 0.30% of the total. Significant temporal (seasonal) genetic subdivision was revealed in chum salmon of the Tauy River. The populations of the Okhotsk Sea coast are very similar genetically to the east Sakhalin populations. The industrial chum salmon population founded and reproduced artificially in the Kulkuty River preserves the genetic similarity of the donor Yama River chum salmon. In the industrial population, we observed a tendency toward reduction of genetic variation over time. The contribution of the Yama population to the gene pool of the Ola chum salmon, (both by natural reproduction and by farming) is small in spite of many large-scale transplantations. However, the consequences of those transplantations are revealed by means of linkage disequilibrium analysis.     

Relation between augmentation index and adiponectin during one-year metformin treatment for nonalcoholic steatohepatosis: effects beyond glucose lowering?

ABSTRACT: BACKGROUND: Insulin resistance (IR) is the major driving force behind development and progression of atherosclerosis in patients with nonalcoholic fatty liver disease (NAFLD). Therefore, correction of IR is a relevant therapeutic target. We performed the current trial to evaluate whether 12- month metformin therapy improves vascular stiffness in patients with NAFLD and to assess if this improvement is associated with change in glucose control, insulin resistance or circulating adiponectin. METHODS: In randomized, placebo controlled study, 63 patients with NAFLD were assigned to one of two groups: Group 1 received daily metformin; Group 2 received placebo. Central aortic augmentation index (AI) was performed using SphygmoCor (version 7.1, AtCor Medical, Sydney, Australia) at baseline, at 4-and 12-month treatment period. Metabolic parameters, insulin resistance markers and serum adiponectin levels were determined. RESULTS: In placebo group: AI did not improve during the treatment period. Liver function and adiponectin levels did not change during the study. In multiple linear regression analysis, the independent predictors of arterial stiffness improvement were metformin treatment and increase in circulating adiponectin levels. Among metformin treated patients: AI decreased significantly during the study. ALP and ALT decreased during initial 4-month treatment period, however raised to the pretreatment levels after 12 months. Serum adiponectin level tended to increase during treatment period with metformin. CONCLUSIONS: Metformin treatment was associated with significant decrease in AI during one year treatment in NAFLD patients. These beneficial vascular effects was associated with exposure to metformin per se as well as change in adiponectin levels suggesting that metformin may mediate its vascular effects via glicemic control-independent mechanisms.     

Far Eastern Mullet Mugil soiuy Basilewsky (Mugilidae,Mugiliformes): The Genetic Structure of Populations and Its Change under Acclimatization

The introduction of Far Eastern mullet (pilengas) in the Azov Sea in the 1970s–1980s has resulted in the formation of a self-reproducing commercial population. We have carried out a comparative population-genetic analysis of the mullet from the native (Primorye, the Sea of Japan basin) and the new (The Azov Sea basin) ranges. Genetic characteristics of three Primorye and three Azov local samples were studied using electrophoretic analysis of 15 enzymes encoded by 21 gene loci. In the Azov mullet, the initial heterozygosity characteristic of the donor population was preserved while the genotype and the allele compositions changed; the changes included a 1.9-fold reduction in the percentage of polymorphic loci and 1.5-fold reduction in the mean number of alleles per locus. The genetic differences between the Azov and the Primorye sample groups were highly significant. In the native range, no genetic differentiation among the mullet samples from different areas was found (G _st = 0.42%), whereas in the Azov Sea basin, the samples from spatially isolated populations (ecological groups) exhibited genetic differences (G _st = 1.38%). The genetic divergence of the subpopulations and the excess of heterozygotes at some loci in the Azov mullet suggest selection processes that formed genetically divergent groups associated with the areas of different salinity in the new range. The salinity level is assumed to be the most probable factor of local differentiating selection during fast adaptation and naturalization of the introduced mullet.     

Controlling the near‐infrared transparency of costal cartilage by impregnation with clearing agents and magnetite nanoparticles

Penetration depth of near‐infrared laser radiation to costal cartilage is controlled by the tissue absorption and scattering, and it is the critical parameter to provide the relaxation of mechanical stress throughout the whole thickness of cartilage implant. To enhance the penetration for the laser radiation on 1.56 μm, the optical clearing solutions of glycerol and fructose of various concentrations are tested. The effective and reversible tissue clearance was achieved. However, the increasing absorption of radiation should be concerned: 5°C‐8°C increase of tissue temperature was detected. Laser parameters used for stress relaxation in cartilage should be optimized when applying optical clearing agents. To concentrate the absorption in the superficial tissue layers, magnetite nanoparticle (NP) dispersions with the mean size 95 ± 5 nm and concentration 3.9 ± 1.1 × 10¹¹ particles/mL are applied. The significant increase in the tissue heating rate was observed along with the decrease in its transparency. Using NPs the respective laser power can be decreased, allowing us to obtain the working temperature locally with reduced thermal effect on the surrounding tissue.      

Encapsulated in silica: genome, proteome and physiology of the thermophilic bacterium Anoxybacillus flavithermus WK1

Background

Gram-positive bacteria of the genus Anoxybacillus have been found in diverse thermophilic habitats, such as geothermal hot springs and manure, and in processed foods such as gelatin and milk powder. Anoxybacillus flavithermus is a facultatively anaerobic bacterium found in super-saturated silica solutions and in opaline silica sinter. The ability of A. flavithermus to grow in super-saturated silica solutions makes it an ideal subject to study the processes of sinter formation, which might be similar to the biomineralization processes that occurred at the dawn of life.

Results

We report here the complete genome sequence of A. flavithermus strain WK1, isolated from the waste water drain at the Wairakei geothermal power station in New Zealand. It consists of a single chromosome of 2,846,746 base pairs and is predicted to encode 2,863 proteins. In silico genome analysis identified several enzymes that could be involved in silica adaptation and biofilm formation, and their predicted functions were experimentally validated in vitro. Proteomic analysis confirmed the regulation of biofilm-related proteins and crucial enzymes for the synthesis of long-chain polyamines as constituents of silica nanospheres.

Conclusions

Microbial fossils preserved in silica and silica sinters are excellent objects for studying ancient life, a new paleobiological frontier. An integrated analysis of the A. flavithermus genome and proteome provides the first glimpse of metabolic adaptation during silicification and sinter formation. Comparative genome analysis suggests an extensive gene loss in the Anoxybacillus/Geobacillus branch after its divergence from other bacilli.     

LKB1 tumor suppressor protein regulates actin filament assembly through Rho and its exchange factor Dbl independently of kinase activity

Background  

Germline mutations in LKB1 result in Peutz-Jeghers Syndrome characterized by intestinal hamartomas and increased incidence of epithelial cancers. LKB1 encodes a serine/threonine kinase that plays an important role in regulating energy metabolism through the AMPK/mTOR signaling pathway. In addition, LKB1 is homologous to PAR-4, a polarity protein first described in C. elegans, while activation of LKB1 in mammalian epithelial cells induces the polarized assembly of actin filaments.