Effect of the lymphocytosis-stimulating factor from Bordetella pertussis on murine lymphoid and hemopoietic cells

Effect of B. pertussis lymphocytosis-promoting factor (LPF) on the lympho-hematopoietic system of mice was studied. The injection of LPF was shown to sharply enhance endogenous colony formation and to induce a severe depletion of thymus cells, reaching its maximum of day 4. Thymocytes obtained on day 2 or 3 after the injection of LPF produced a suppressive effect on endogenous colony formation. The proliferative activity of hematopoietic stem cells sharply increased under the influence of LPF, though it had no radioprotective action. On the following day after the injection of LPF a steep rise in the number of hematopoietic stem cells was observed in the blood of mice: their content increased 20-fold in comparison with the control level. These data may be important for the evaluation of the side effects of pertussis vaccine on the lympho-hematopoietic system.     

A revision of current data and views on membrane hydrolysis and transport in the mammalian small intestine based on a comparison of techniques of chronic and acute experiments: experimental re-investigation and critical review

Literature data and the results of our investigations using both generally accepted and original perfusion techniques of the isolated loop of the rat small intestine in in vivo experiments are reviewed. Significant differences in the functioning of the small intestine under conditions of acute and chronic experiments are revealed. It has been established that in chronic experiments as compared to acute ones: (a) the absorption of glucose, galactose, fructose and glycine is 2-5 times higher; (b) Kt as well as Jmax values of the transport of these nutrients differ considerably; (c) Na+-independent mechanism of glucose and glycine transport predominates; (d) higher rates of membrane hydrolysis and more effective interactions between enzyme and transport systems of the enterocyte brush border membranes are observed; (e) functional characteristics of the small intestine affected by various experimental factors are more stable. The conclusion is made that it is necessary to revise current views of the scale and regularities of digestive-transport processes in the small intestine under physiological conditions. The importance of the suggested approaches for general and comparative physiology and biochemistry is discussed.     

How does a tigress balance the opposing constraints of raising cubs?

Mammal Research - The persistence of wildlife populations largely depends on females successfully rearing young through the earliest, most vulnerable period. During this period, mothers must...     

Factors, determining the activity of a new antimicrobial substance from fish oils from various species

The induction of antimicrobial activity of a new preparation, an aqueous fraction of water-oil emulsion oxidized by air oxygen, was studied. The effect of various factors (the degree of unsaturation of the initial oil and the content of oil oxidation products in obtained preparation) on the antimicrobial activity was determined. The antimicrobial activity of the preparation was induced by oil oxidation. The preparation produced from sardine Sardinops melanostica oil (33.95% of polyunsaturated fatty acids) displayed the highest antimicrobial activity. The antimicrobial activity was shown in water-soluble oil oxidation products.     

Protein kinase Cepsilon (PKCepsilon) and Src control PKCdelta activation loop phosphorylation in cardiomyocytes

Protein kinase Cdelta (PKCdelta) is unusual among AGC kinases in that it does not require activation loop (Thr(505)) phosphorylation for catalytic competence. Nevertheless, Thr(505) phosphorylation has been implicated as a mechanism that influences PKCdelta activity. This study examines the controls of PKCdelta-Thr(505) phosphorylation in cardiomyocytes. We implicate phosphoinositide-dependent kinase-1 and PKCdelta autophosphorylation in the "priming" maturational PKCdelta-Thr(505) phosphorylation that accompanies de novo enzyme synthesis. In contrast, we show that PKCdelta-Thr(505) phosphorylation dynamically increases in cardiomyocytes treated with phorbol 12-myristate 13-acetate or the alpha(1)-adrenergic receptor agonist norepinephrine via a mechanism that requires novel PKC isoform activity and not phosphoinositide-dependent kinase-1. We used a PKCepsilon overexpression strategy as an initial approach to discriminate two possible novel PKC mechanisms, namely PKCdelta-Thr(505) autophosphorylation and PKCdelta-Thr(505) phosphorylation in trans by PKCepsilon. Our studies show that adenovirus-mediated PKCepsilon overexpression leads to an increase in PKCdelta-Thr(505) phosphorylation. However, this cannot be attributed to an effect of PKCepsilon to function as a direct PKCdelta-Thr(505) kinase, since the PKCepsilon-dependent increase in PKCdelta-Thr(505) phosphorylation is accompanied by (and dependent upon) increased PKCdelta phosphorylation at Tyr(311) and Tyr(332). Further studies implicate Src in this mechanism, showing that 1) PKCepsilon overexpression increases PKCdelta-Thr(505) phosphorylation in cardiomyocytes and Src(+) cells but not in SYF cells (that lack Src, Yes, and Fyn and exhibit a defect in PKCdelta-Tyr(311)/Tyr(332) phosphorylation), and 2) in vitro PKCdelta-Thr(505) autophosphorylation is augmented in assays performed with Src (which promotes PKCdelta-Tyr(311)/Tyr(332) phosphorylation). Collectively, these results identify a novel PKCdelta-Thr(505) autophosphorylation mechanism that is triggered by PKCepsilon overexpression and involves Src-dependent PKCdelta-Tyr(311)/Tyr(332) phosphorylation.     

Structural and functional analyses of methyl-lysine binding by the malignant brain tumour repeat protein Sex comb on midleg

Sex comb on midleg (Scm) is a member of the Polycomb group of proteins involved in the maintenance of repression of Hox and other developmental control genes in Drosophila. The two malignant brain tumour (MBT) repeats of Scm form a domain that preferentially binds to monomethylated lysine residues either as a free amino acid or in the context of peptides, while unmodified or di- or trimethylated lysine residues are bound with significantly lower affinity. The crystal structure of a monomethyl-lysine-containing histone tail peptide bound to the MBT repeat domain shows that the methyl-lysine side chain occupies a binding pocket in the second MBT repeat formed by three conserved aromatic residues and one aspartate. Insertion of the monomethylated side chain into this pocket seems to be the main contributor to the binding affinity. Functional analyses in Drosophila show that the MBT domain of Scm and its methyl-lysine-binding activity are required for repression of Hox genes.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Polyunsaturated molecular species of galactolipids: Markers of zooxanthellae in a symbiotic association of the soft coral Capnella sp. (Anthozoa: Alcyonacea)

A method that uses marker fatty acids (FAs) is widely applied in investigations of trophic and symbiotic relationships. In a search for new lipid markers, we determined the total lipid FA composition, as well as the composition of molecular species of mono- and digalactosyl diacylglycerols (MGDGs and DGDGs), which are specific galactolipids of thylakoid membranes, in zooxanthellae (endosymbiotic dinoflagellates) of the tropical soft coral Capnella sp. Some FAs of zooxanthellae were suggested for use as marker polyunsaturated FAs (PUFAs). Thirteen molecular species of MGDGs and ten molecular species of DGDGs were detected using the method of high-resolution tandem mass spectrometry. All marker PUFAs of zooxanthellae were found in acyl groups of galactolipids. The major molecular species of DGDGs (18:4/18:4, 18:4/20:5, and 16:2/22:6) and the unique molecular species of MGDGs (16:4/18:5) were described. The identification of several polyunsaturated molecular species of galactolipids that contain marker FAs allowed us to propose that this lipid group be used as molecular lipid markers of zooxanthellae for the study of symbiont–host interactions in soft corals.     

Ser1928 is a common site for Cav1.2 phosphorylation by protein kinase C isoforms

Voltage-dependent Ca(2+) channel (Ca(v)1.2, L-type Ca(2+) channel) function is highly regulated by hormones and neurotransmitters in large part through the activation of kinases and phosphatases. Regulation of Ca(v)1.2 by protein kinase C (PKC) is of significant physiologic importance, mediating, in part, the cardiac response to hormonal regulation. Although PKC has been reported to mediate activation and/or inhibition of Ca(v)1.2 function, the molecular mechanisms mediating the response have not been definitively elucidated. We show that PKC forms a macromolecular complex with the alpha(1c) subunit of Ca(v)1.2 through direct interaction with the C terminus. This interaction leads to phosphorylation of the channel in response to activators of PKC. We identify Ser(1928) as the residue that is phosphorylated by PKC in vitro and in vivo. Ser(1928) has been identified previously as the site mediating, in part, the protein kinase A up-regulation of channel activity. Thus, the protein kinase A and PKC signaling pathways converge on the Ca(v)1.2 complex at Ser(1928) to increase channel activity. Our results identify two mechanisms leading to regulation of Ca(v)1.2 activity by PKC: pre-association of the channel with PKC isoforms and phosphorylation of specific sites within the alpha(1c) subunit.