On the interpretation of some planktonology equations

Summary The concept of the mean value of a function is used to interpret some population-dynamics equations. The well-known formula for the per capita growth rate r gives a precise mean value for any (not only exponentially growing) populations. This result is used to derive the birth and death rate equations of Paloheimo (1974) with minimal initial limitations.Abbreviations t time - N number of animals - E number of eggs - r specific (i.e. per capita) population growth rate - b specific birth rate - d specific death rate - D duration of embryonic development     

Testing of the method for water microleakage detection from OH hydroxyl spectral lines at the L-2M stellarator

Results are presented from L-2M stellarator experiments on testing a possible method for detection of water microleakages in the cooling system of the first wall and vacuum chamber of ITER. The method consists in the spectroscopic detection of spectral lines of the OH hydroxyl, which forms via the dissociation of water molecules in plasma. Emission in the spectral band of 305–310 nm can be detected even at water leakage rates less than 10^?4 Pa m³/s. Chemical reactions between water and boron compounds on the vacuum chamber wall delay the detection of leakages up to ～2000 s. A similar phenomenon can be expected when a leakage will occur in ITER, where the materials suggested for the first wall (Be, Li) can also chemically react with water.     

Seasonal Variations in the Structure of an Anoxygenic Phototrophic Bacterial Community from the Meromictic Lake Trekhtsvetnoe (Kandalaksha Bay,White Sea)

Microbiology - The community of anoxygenic phototrophic bacteria (APB) from the water column of the meromictic Lake Trekhtsvetnoe (Kandalaksha Bay, White Sea, Russia) was studied in March 2012 and...     

Classification of the forebrain striatum neurons in birds

Polymorphism of neurons in the basic fields of the forebrain striatum of birds was described using specially developed classification of neurons in Nissl preparations. Birds with different degrees of development of elementary rational activity were studied: Corvus monedula, Columba livia, Coturnix coturnix, and Melopsittacus undulatus. According to the proposed method, the neurons were classified in 3 basic types and 2 additional, 6 subtypes and 26 classes. It was found that in the higher brain regions of Corvus monedula, birds with advanced rational activity, there are a greater variety and number of complex associative stellate cells than in birds with poorly developed rational activity (Columba livia and Coturnix coturnix).     

Comparative embryology of nematodes and the law of embryo similarity

Two types of embryonic development can be distinguished within nematodes, with a variable (Enoplia) or invariant (remaining species) cleavage. In the case of invariant cleavage two main variants of cell lineage are presented in nematodes, with the posterior (Rhabditea) or anterior (Dorylaimida) localization of endoderm material at the two-cell stage. This classification is in a good agreement with some modern nematode taxonomy and it is supported by molecular phylogeny studies. The variable cleavage is plesiomorphic. Traditional concept of "mosaic" cleavage is not applicable for nematodes as inductive interactions and a regulation of experimental interventions are usual attributes of any mode of nematode development. The representatives of order Rhabditida have almost identical cell lineage, but at the same time they have strong interspecific differences in mechanisms of ooplasmic segregation any early inductive interactions. The diversity of geometric patterns in the early cleavage, often at the level of individual random variations, is a usual characteristic of nematodes including species with the invariant cleavage. Thus, the early stages of nematode development are evolutionary very flexible, but at the course of embryonic development similarity of different species is progressively increased up to the uniform morphogenetic stages. The dynamics of variation in nematode development contradict to the von Baer's law but are in an agreement with the modern "hourglass model" (Doboul, 1994; Raff, 1986).     

Dephosphorylation of beta2-syntrophin and Ca2+/mu-calpain-mediated cleavage of ICA512 upon stimulation of insulin secretion

Islet cell autoantigen (ICA) 512 is a receptor-tyrosine phosphatase-like protein associated with the secretory granules of neuroendocrine cells, including pancreatic beta-cells. Binding of its cytoplasmic tail to beta2-syntrophin suggests that ICA512 connects secretory granules to the utrophin complex and the actin cytoskeleton. Here we show that stimulation of insulin secretion from INS-1 cells triggers the biosynthesis of pro-ICA512 and the degradation of its mature form. Inhibition of calpain, which is activated upon stimulation of insulin secretion, prevents the Ca2+-dependent proteolysis of ICA512. In vitro mu-calpain cleaves ICA512 between a putative PEST domain and the beta2-syntrophin binding site, whereas binding of ICA512 to beta2-syntrophin protects the former from cleavage. beta2-syntrophin and its F-actin-binding protein utrophin are enriched in subcellular fractions containing secretory granules. ICA512 preferentially binds phospho-beta2-syntrophin and stimulation of insulin secretion induces the Ca2+-dependent, okadaic acid-sensitive dephosphorylation of beta2-syntrophin. Similarly to calpeptin, okadaic acid inhibits ICA512 proteolysis and insulin secretion. Thus, stimulation of insulin secretion might promote the mobilization of secretory granules by inducing the dissociation of ICA512 from beta2-syntrophin-utrophin complexes and the cleavage of the ICA512 cytoplasmic tail by mu-calpain.