Electron Microscopy Study of Anterior Neuropituitary of the Sterlet Acipenser ruthenus

Structural organization of sterlet anterior neuropituitary (ANP), a homologue of the median tubercle of Tetrapoda, was studied by method of electron microscopy. The ANP was conventionally divided in three zones in dorsoventral direction. Neurosecretory fibers (NsF) were concentrated mainly in the central and in the external zones. Terminals of NsF are directly adjacent to the basal membrane (BM) of the brain vascular sheath to form a morphological substrate for release of neurohormones into the pericapillary space. The presence of invaginations of the brain connective tissue sheath, which are in a close contact with NsF, indicates an increase of the area of neurosecretory contacts. Neurosecretory granules (NsG) of various shape and size are revealed in NsF and their terminals. Comparison of light-microscopy immunohistochemical data with localization of NsF terminals containing NsG of different diameters allows reconstructing distribution of neurosecretory elements of various ergicity in the ANP. Patterns of co-localization of various biologically active substances were revealed in the same varicose dilatations or terminals. Detection of typical synaptic contacts in the sterlet ANP indicates possibility of the cholinergic pituitary regulation, alongside with the peptide- and monoaminergic regulation.     

Isolation and properties of carboxylesterase from hemolymph of the silkworm Bombyx mori L

An original procedure for isolation and purification of carboxylesterase from the hemolymph of stage V larvae of one of Bombyx mori strains including precipitation with 10% polyethyleneglycol, ion-exchange chromatography on Sephadex G-200 and chromatography on DEAE-Sephadex A-50, has been developed. The specific activity of the enzyme after purification makes up to 1250 units per mg of protein with a 59% yield. Some physicochemical properties of the enzyme (Mr = 69 000, pI congruent to 4.9, temperature optimum = 40 degrees, pH optimum = 7.2 Km for alpha-naphthyl- and beta-naphthylacetate = 0.11 X 10(-3) and 0.52 X 10(-3) M, respectively) have been determined. Using immunodiffusion in agar gel, the antigenic identity of the enzymes isolated from the hemolymph of two silkworm species has been established.     

Tissue-specific mammary gland antigen identified by monoclonal antibodies

A new antigen of mammary tumor cells has been revealed using monoclonal antibodies. A similar antigen was detected also in certain types of secretory epithelia of oesophagus, stomach, salivary gland, and embryonic large intestine. Upon malignization, antigen persists in invasive ductal cancer of mammary gland and is expressed in cancers of ovary and rectum. The molecular weight of the antigen is greater than 2,000 kD.     

Red-breasted goose colonies on the Taimyr Peninsula: Factors responsible for the proximity of goose nests to nests of peregrine falcons,rough-legged buzzards,and snowy owls

Red-breasted goose colonies have been studied near Medusa Bay (73°21′N, 80°32′E), on the northwestern Taimyr Peninsula, and along the Agapa River (70°11′N, 86°15′E) down to its mouth (71°26′N, 89° 13′E), in the central Taimyr Peninsula. Red-breasted geese nesting near peregrine falcons are protected by the falcons from arctic foxes; however, they are sometimes attacked by the falcons themselves. In the colonies near peregrine falcon nests, the vast majority of goose nests were situated no farther than 100 m from the falcon nest. When food is abundant, falcons protect a larger area around their nest. The distance between the falcon nest and the surrounding goose nests is inversely related to the falcon’s activity. In years of higher falcon activity, falcons prevent red-breasted geese from nesting as close to their nest as in years of lower falcon activity. Additional stimuli are required for red-breasted geese to form colonies near rough-legged buzzard nests. The distance between snowy owl nests and red-breasted goose nests was smaller when arctic foxes were abundant than when they were scarce.