Meta‐population structure and the evolutionary transition to multicellularity

The evolutionary transition to multicellularity has occurred on numerous occasions, but transitions to complex life forms are rare. Here, using experimental bacterial populations as proxies for nascent multicellular organisms, we manipulate ecological factors shaping the evolution of groups. Groups were propagated under regimes requiring reproduction via a life cycle replete with developmental and dispersal (propagule) phases, but in one treatment lineages never mixed, whereas in a second treatment, cells from different lineages experienced intense competition during the dispersal phase. The latter treatment favoured traits promoting cell growth at the expense of traits underlying group fitness – a finding that is supported by results from a mathematical model. Our results show that the transition to multicellularity benefits from ecological conditions that maintain discreteness not just of the group (soma) phase, but also of the dispersal (germline) phase.     

Reproductive Strategies and the Origin of Parapatric and Sympatric Forms of Arctic Charr Salvelinus alpinus (Salmonidae) in the System of Lakes Bol’shoe Leprindo and Maloe Leprindo (Northern Transbaikalia)

Journal of Ichthyology - In the system of lakes Bol’shoe Leprindo and Maloe Leprindo (Lena basin, Transbaikalia), spawning of two isolated populations of the dwarf form of Arctic charr...     

Progression of pulmonary tuberculosis and efficiency of bacillus Calmette-Guérin vaccination are genetically controlled via a common sst1-mediated mechanism of innate immunity

Using a mouse model for genetic analysis of host resistance to virulent Mycobacterium tuberculosis, we have identified a genetic locus sst1 on mouse chromosome 1, which controls progression of pulmonary tuberculosis. In vitro, this locus had an effect on macrophage-mediated control of two intracellular bacterial pathogens, M. tuberculosis and Listeria monocytogenes. In this report, we investigated a specific function of the sst1 locus in antituberculosis immunity in vivo, especially its role in control of pulmonary tuberculosis. We found that the sst1 locus affected neither activation of Th1 cytokine-producing T lymphocytes, nor their migration to the lungs, but rather controlled an inducible NO synthase-independent mechanism of innate immunity. Although the sst1(S) macrophages responded to stimulation with IFN-gamma in vitro, their responsiveness to activation by T cells was impaired. Boosting T cell-mediated immunity by live attenuated vaccine Mycobacterium bovis bacillus Calmette-Guérin or the adoptive transfer of mycobacteria-activated CD4(+) T lymphocytes had positive systemic effect, but failed to improve control of tuberculosis infection specifically in the lungs of the sst1(S) animals. Thus, in the mouse model of tuberculosis, a common genetic mechanism of innate immunity mediated control of tuberculosis progression in the lungs and the efficiency of antituberculosis vaccine. Our data suggest that in immunocompetent humans the development of pulmonary tuberculosis and the failure of the existing vaccine to protect against it, in some cases, may be explained by a similar defect in a conserved inducible NO synthase-independent mechanism of innate immunity, either inherited or acquired.     

Distinct Distribution of Ectopically Expressed Histone Variants H2A.Bbd and MacroH2A in Open and Closed Chromatin Domains

Background

It becomes increasingly evident that nuclesomes are far from being identical to each other. This nucleosome diversity is due partially to the existence of histone variants encoded by separate genes. Among the known histone variants the less characterized are H2A.Bbd and different forms of macroH2A. This is especially true in the case of H2A.Bbd as there are still no commercially available antibodies specific to H2A.Bbd that can be used for chromatin immunoprecipitation (ChIP).

Methods

We have generated HeLa S3 cell lines stably expressing epitope-tagged versions of macroH2A1.1, H2A.Bbd or canonical H2A and analyzed genomic distribution of the tagged histones using ChIP-on-chip technique.

Results

The presence of histone H2A variants macroH2A1.1 and H2A.Bbd has been analyzed in the chromatin of several segments of human chromosomes 11, 16 and X that have been chosen for their different gene densities and chromatin status. Chromatin immunoprecipitation (ChIP) followed by hybridization with custom NimbleGene genomic microarrays demonstrated that in open chromatin domains containing tissue-specific along with housekeeping genes, the H2A.Bbd variant was preferentially associated with the body of a subset of transcribed genes. The macroH2A1.1 variant was virtually absent from some genes and underrepresented in others. In contrast, in closed chromatin domains which contain only tissue-specific genes inactive in HeLa S3 cells, both macroH2A1.1 and H2A.Bbd histone variants were present and often colocalized.

Conclusions

Genomic distribution of macro H2A and H2A.Bbd does not follow any simple rule and is drastically different in open and closed genomic domains.     

Immune stratum of the population in relation to the causative agent of pseudotuberculosis

The state of population immunity may be controlled by analyses of placental, abortion, and donor blood. The existence of a high direct correlation between the level of the immune stratum of the population and pseudotuberculosis morbidity has been revealed. Regression equations suitable for the prognostication of pseudotuberculosis morbidity have been obtained by means of computers.     

Special Traits in Early Ontogenesis of the Endemic Lacustrine Form of the Salvelinus malma Сomplex (Salmonidae), Small-Mouth Form,from Lake Kronotskoe (Eastern Kamchatka)

Journal of Ichthyology - Growth, sequences of anlage, and special traits of transient states are investigated in skeletal elements (skull bones and serial structures—teeth, gill rakers, fin...     

Juvenile divergence in adaptive traits among seven sympatric fish ecomorphs arises before moving to different lacustrine habitats

Identifying the mechanisms initiating sympatric diversification in vertebrates has remained a conceptual challenge. Here, we analyse an assemblage of sympatric charr (Salvelinus malma) morphs from landlocked Lake Kronotskoe basin as a model to uncover the divergence pathways in freshwater fishes during the early life history stages. All morphs have distinct developmental biology, but a similar developmental rate retardation compared to the ancestor. Our study reveals that adult morphological differences, which acquire functionality at maturation, originate in the early juvenile stages due to heterochrony in skeletogenesis and allometric changes triggered by variation in metabolic activity. The craniofacial differences among the morphs result from asynchronous development of several skeletal modules. The accelerated ossification of teeth‐armed bones occurs in predatory feeding morphs, whereas cranial cover ossification is promoted in benthivorous morphs. These contrasting growth patterns have led to seven phenotypes that span a range far beyond the ancestral variability. The most distinct morphs are a riverine spawning, epilimnetic predator and a lacustrine spawning, profundal benthic feeder. Taken together, we argue that the adaptive morphological differentiation in these sympatric freshwater fishes is driven by diverging patterns in ossification rate and metabolic activity against a background of uneven somatic growth. This divergence is primarily associated with basic environmental differences on the nursery grounds that might be unrelated to resource use. This nonheritable phenotype divergence is then exposed to natural selection that could result in further adaptive genetic changes.     

Pond smelt <Emphasis Type="Italic">Hypomesus olidus</Emphasis>, a new species of the ichthyofauna of the Commander Islands

The population of pond smelt Hypomesus olidus has been registered for the first time in the water bodies of Bering Island (Commander Islands). The spawning of this species has been observed in the Sarannoe Lake system, and the maturing breeders have been caught in the freshwater-brackish Gavanskoe Lake system. The spawning grounds, the spawning period, the environment, and the morphology of the breeders have been described. The ratio of Ca and Sr isotopes in the otoliths of the pond smelt inhabiting the Sarannoe Lake system evidenced that this species here was presented by the resident ecotype. The problem of the smelt phylogeny and resettlement in the northern Pacific Ocean is discussed.     

The development of an artificial hybrid and revealing elements of reproductive isolation between sympatric forms of Dryagin’s char and <Emphasis Type="Italic">Salvelinus alpinus</Emphasis> complex (Salmonidae) from Sobachye Mountain Lake (Taimyr)

The embryonic-larval development (at 3°C) of a hybrid between sympatric lake forms of Arctic char Salvelinus alpinus complex (large females of Dryagin’s char x male goggle-eyed char) from the polar mountain Lake Sobachye (the Norilo-Pyasina water system, Taimyr) was studied. No morphological disturbances were found in the embryonic membrane during development. After hatching, because of yolk sac soaking and blood circulation disturbances along its vessels, about 15% of specimens perished. The most mass disturbances in the development of free embryos and larvae that were manifested in the body curvature, loss of mobility, and subsequent death of a greater proportion of specimens were caused by modifications of differentiation of mesenchymal cells responsible for the axial skeleton formation. It is suggested that anomalies in osteogenesis and a high variation of age when dermal cranial bones (praeoperculum and frontale) appear that bear seismosensory system canal are related to the conflict of genetic programs of the development of parental forms. The rate of embryonic larval development of hybrid specimens exceeds that in the lake small form of Arctic char from Lake Davatchan (Transbaikalia) reared under the same conditions. The reproductive isolation of sympatric Dryagin’s char and goggle-eyed char in Lake Sobachye is provided by both pre- and postcopulation mechanisms. A possible mechanism of formation of reproductive isolation of sympatric forms related to colonization by them of a deep-water biotope is discussed.     

Mechanism of the effect of nonionizing radiation on animals at the level of sensory systems

In three series of experiments on mice (CBA X C57BL)F1 and Wistar rats a study was made of the effect of microwaves (0.9 GGz, 0.4 mW/cm2, 10 min) on the EEG reaction of adopting the photostimulation rhythm by rats; the effect of microwaves (0.6 GGZ, 0.04 mW/cm2, 5 min) and gamma-quanta (60Co, 0.5 Gy) on the reaction of avoiding by mice of cooled surfaces, and the effect of microwaves (9.8 GGz, 0.04 mW/cm2, 5 min) on the reaction of avoiding the water pool. The results obtained are discussed with regard to the hypothesis that the biological effects of weak microwave radiation may be realized at the nervous system level via cutaneous ceptors.