Role of intracortical inhibition in forming homo- and heterosensory interaction in sensorimotor cortex neurons in kittens

Homo- and heterosensory interaction were investigated in sensorimotor cortex neurons before and after picrotoxin application to anesthetized and immobilized kittens belonging to three age groups (12–30 days, 31–47 days, and 2–4 months old). Only slight inhibition of response to presentation of a second stimulus was observed in a small proportion of cells in the youngest age group at test intervals of 100, 200, and 300 msec. Picrotoxin application only produced the effect of raised background activity. Numbers of neurons with partially or fully inhibited response to test stimuli (especially spaced at 100 msec intervals) rose in the middle and older age groups. The dynamics of heterosensory interaction and how this is affected by picrotoxin application gradually approximated to that observed with adult animals. The subject of the development of inhibitory mechanisms and how they contribute to the organization of homo- and heterosensory interaction during early postnatal ontogenesis is considered in the light of the results obtained.A. A. Ukhtomsii Institute of Physiology, Leningrad. A. A. Zhdanov State University, Leningrad. Translated from Neirofiziologiya, Vol. 20, No. 2, pp. 234–243, March–April, 1988.     

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.      

Molecular Genetic Analysis of the DXS52Polymorphism in Populations of the Volga–Ural Region

The DXS52polymorphic locus mapping to the 5"-region of the blood-clotting factor VIII gene on the X chromosome was genotyped in seven Volga–Ural ethnic groups (Bashkirs, Tatars, Chuvashes, Maris, Mordovians, Udmurts, and Komis). A total of 47 different genotypes and 15 allelic variants of this locus were described. Substantial intra- and interpopulation heterogeneity of the ethnic groups studied in respect to frequency and distribution of the DXS52alleles and genotypes was demonstrated. The unimodal DXS52allele frequency distribution pattern with the peak at 1690 bp was typical to Mordovians and Komis. Chuvashes and Maris, as well as Udmurts, were characterized by bimodal frequency distribution patterns, with the peaks at 1690 and 670 bp, and 1690 and 1390 bp, respectively. Moreover, Bashkirs and Tatars displayed trimodal DXS52allele frequency distribution patterns with the peaks at 1690, 1390, and 670 bp. The DXS52allele frequency distribution patterns described in populations of the Volga– Ural region were found to be remarkably different from those established for the mixed Moscow population and the population of Western Europe. These data indicate that the DXS52locus is highly informative, and this polymorphic system can serve as a molecular marker for population genetic studies.     

Molecular genetic study of the factor VIII gene in families from Bashkir with hemophilia A

The distribution of hemophilia A was studied in Bashkortostan. The factor VIII gene of the blood coagulation system was analyzed in 34 patients with hemophilia A and 48 of their close relatives. Inversion of intron 22 of the factor VIII gene was revealed in nine cases, which comprised 30% of the total sample analyzed. The type II and type III of this mutation occurred at a relatively high frequency, which may be explained by the founder effect and genetic drift. The allelic frequencies of the polymorphic locus HindIII at intron 19 were similar; a substantial allelic heterogeneity of both microsatellite (CA)-repeats at intron 13 and the DXS52 locus were found on normal and mutant X chromosomes. The molecular genetic analysis of (CA)-repeats and the loci HindIII and DXS52 in families with hemophilia A makes it possible to reveal up to 89% of the informative families.     

Dating the origin of the CCR5-Delta32 AIDS-resistance allele by the coalescence of haplotypes.

The CCR5-Delta32 deletion obliterates the CCR5 chemokine and the human immunodeficiency virus (HIV)-1 coreceptor on lymphoid cells, leading to strong resistance against HIV-1 infection and AIDS. A genotype survey of 4,166 individuals revealed a cline of CCR5-Delta32 allele frequencies of 0%-14% across Eurasia, whereas the variant is absent among native African, American Indian, and East Asian ethnic groups. Haplotype analysis of 192 Caucasian chromosomes revealed strong linkage disequilibrium between CCR5 and two microsatellite loci. By use of coalescence theory to interpret modern haplotype genealogy, we estimate the origin of the CCR5-Delta32-containing ancestral haplotype to be approximately 700 years ago, with an estimated range of 275-1,875 years. The geographic cline of CCR5-Delta32 frequencies and its recent emergence are consistent with a historic strong selective event (e.g. , an epidemic of a pathogen that, like HIV-1, utilizes CCR5), driving its frequency upward in ancestral Caucasian populations.     

Fast and aimed delivery of voltage-sensitive dyes to mammalian brain slices by biolistic techniques

Fast voltage-sensitive dyes (VSD) are widely used in modern neuroscience for optical recording of electrical potentials at many levels, from single cell compartment to brain areas, containing populations of many neural cells. The more lipophilic a VSD, the better signal-to-noise ratio of the optical signal, but there are no effective ways to deliver a water-insoluble dye into the membrane of live cell. Here we report a new protocol based on rapid biolistic delivery of VSDs, which is optimal for further recordings of optical signals from live neurons of rat brain slices. This protocol allows us to stain locally (150 mkm) neural somata of brain structures with a Golgi-like pattern, and a VSD propagates even to distant neurites of stained cells very quickly. This technique also can be used for rapid local delivery of any lipophilic and water-insoluble substances into live cells, further optical recording of neural activity, and analysis of potential propagation in a nerve cell.     

Some aspects of the regeneration process carried out by means of pluripotent stem cells

This work is devoted to the vital topic of regeneration by stem cells. Cells-predecessors and differentiated cells can divide a limited number of times (Alberts et al., 1994) and are not capable of providing tissue regeneration throughout the ontogenesis. The tissue renewal during such a long period is impossible without participation of a specialized system responsible for regeneration. The given system is submitted by stem cells which are capable of being differentiated in all types of somatic cells and in a line of germ cells, and also have ability to self-renew during the whole life of an organism. Results of our research suggest that stem cells make up a universal mechanism of regeneration which has been formed during evolution.     

Endocellular aminopeptidase from <Emphasis Type="Italic">Astasia longa</Emphasis>

A new aminopeptidase was isolated from the biomass of the flagellate Astasia longa by precipitation with ammonium sulfate, gel filtration, and affinity chromatography on Arginine-Silochrome in 41% yield and with purification degree 490. The enzyme is irreversible inhibited by mercury chloride, EDTA, o-phenanthroline and, partially, bestatin and zinc chloride. It has an optimum pH 8.5 toward the hydrolysis of a synthetic chromogenic substrate Ala-pNA. The enzyme molecular mass is 45 kDa, isoelectric point 5.5, and temperature optimum 45°C. The enzyme most effectively hydrolyzes p-nitroanilides of alanine, arginine, and leucine; it is classified as metalloaminopeptidase.