Early Oligocene fruits and leaves of Burretiodendron (Malvaceae s.l.) from South China

The genus Burretiodendron Rehder is currently endemic to an area near the China–Vietnam border and the limestone mountains of Thailand and Myanmar. The fossil records of this genus were previously found only from the Miocene of Yunnan, Southwest China, and the Oligocene of Guangxi, South China. Here, we describe fossil fruits and associated leaves of Burretiodendron, which were discovered in the lower Oligocene Shangcun Formation of the Maoming Basin, Guangdong, South China. Morphological comparison with extant and fossil Burretiodendron taxa indicates that fruit fossils belong to the species Burretiodendron parvifructum J. Lebreton Anberrée & Z. K. Zhou. This is one of the earliest fossil records of the genus, providing additional evidence for the early biogeographic history of this genus and supporting the inference that the genus originated in South China. According to the habitat conditions of modern species, we speculate that there were limestone mountains around the Maoming Basin in the early Oligocene.     

Chronic stress and forming of psychoemotional state during prepubertal period in rats

Immediate and long-lasting effects of chronic stress during prepubertal period (21-32 postnatal days) on anxiety- and depression-related behavior were studied in Wistar and ISIAH (inherited stress-induced arterial hypertension) rats. Significant interstrain differences were found. Both juvenile and adult ISIAH rats were less anxious in the elevated plus-maze and less depressed in the forced swimming test. Immediate effects of the prepubertal stress were similar in both rat strains and depended on the type of stimulation. Long-lasting effects were genotype-dependent. Chronic prepubertal handling exerted an anxiolytic effect in young ISIAH and Wistar rats and adult Wistar rats. Immediate anxiogenic effect of prepubertal unpredictable stress was preserved only in adult ISIAH rats. Depression-related behavior was intensified by the unpredictable stress in young animals, whereas the long-lasting effect was observed only in adult hypertensive rats.     

Melatonin accelerates reentrainment of the circadian rhythm of its own production after an 8-h advance of the light-dark cycle

Summary The rhythm in melatonin production in the rat is driven by a circadian rhythm in the pineal N-acetyltransferase (NAT) activity. Rats adapted to an artificial lighting regime of 12 h of light and 12 h of darkness per day were exposed to an 8-h advance of the light-dark regime accomplished by the shortening of one dark period; the effect of melatonin, triazolam and fluoxetine, together with 5-hydroxytryptophan, on the reentrainment of the NAT rhythm was studied.In control rats, the NAT rhythm was abolished during the first 3 cycles following the advance shift. It reappeared during the 4th cycle; however, the phase relationship between the evening rise in activity and the morning decline was still compressed.Melatonin accelerated the NAT rhythm reentrainment. In rats treated chronically with melatonin at the new dark onset, the rhythm had already reappeared during the 3rd cycle, in the middle of the advanced night, and during the 4th cycle, the phase relationship between the evening onset and the morning decline of the NAT activity was the same as before the advance shift. In rats treated chronically with melatonin at the old dark onset or in those treated with melatonin 8 h, 5 h and 2 h after the new dark onset during the 1st, 2nd and 3rd cycle, respectively, following the advance shift, the NAT rhythm reappeared during the 3rd cycle as well but in the last third of the advanced night only.Neither triazolam nor fluoxetine together with 5-hydroxytryptophan administered around the new dark onset facilitated NAT rhythm reentrainment after the 8-h advance of the light-dark cycle.Abbreviations NAT N-acetyltransferase - LD cycle light-dark cycle - CT circadian time - LD xy light dark cycle comprising x h of light and y h of darkness     

New data on the systematics of the species of the Dolichopus sublimbatus Becker group (Diptera, Dolichopodidae)

The holotype of the species Dolichopus sublimbatus Becker, 1917 is redescribed. Illustrations of the hypopygium of this species are given for the first time. A new species, Dolichopus kuznetsovi sp. n., is described from Primorskii Territory. A key to the species of the Dolichopus sublimbatus group is given.     

Downstream migration and feeding of young coho salmon Oncorhynchus kisutch in the northern part of the range in Kamchatka

Downstream migration of young coho salmon in the northern part of the range is observed at different ontogenetic stages. Three migration periods were identified: passive migration of yearlings within the spawning river; migration of parr older than 1 year from the spawning tributary to the main river; and migration of smoltifying fish from the river to the sea. The smoltification and seaward migration of the bulk of young salmons from the Kalkaveem River takes place at the age of 2 years. Mass downstream migration of young coho salmons starts in early June at 9°C. No clear diel pattern was observed in the migration of young coho salmon. The lowest migration activity was observed from sunrise to noon (3:00–12:00) when the feeding activity of young salmons increases.     

Enkephalin and cyclic nucleotide content in the brain structures of rats at different stages of the formation and development of alcoholic dependence

Rats with increased alcohol motivation have been found to have a rise in enkephalin levels in limbic cortex and a decrease in met-enkephalin levels in the brain basal ganglia. Reduction of met-enkephalin to leu-enkephalin ratio in basal ganglia, limbic cortex and hypothalamus may serve as an index of increased inclination to ethanol in these animals. Alcohol dependence is characterized by reduced cAMP content in the majority of brain structures studied, sharply decreased met-enkephalin levels in limbic cortex and hypothalamus, and diminished cAMP and cGMP content in hypothalamus. In the third stage of experimental alcoholism the partial normalization of met-enkephalin and cAMP levels is observed in brain structures, with cGMP content increased in hypothalamus and considerably reduced in basal ganglia.     

Transport ATPases in the erythrocytes of rats acclimatized to intermittent altitude hypoxia

The activity of Na+/K+- and Ca2+-ATPase and some allosteric properties of Na+/K+-ATPase were studied in whole erythrocytes and their membrane preparations (ghosts) from rats exposed to intermittent altitude hypoxia (10 and 24 exposures, 8 h/day in an altitude chamber, stepwise up to an altitude of 7,000 m). Ca2+-ATPase activity was increased both in whole erythrocytes and ghosts after the first phase of acclimatization (10 exposures). In a standard incubation medium (containing 3 mmol.l-1 MgCl2 ), Na+/K+-ATPase activity in the ghosts was also increased after the initial phase of acclimatization whereas in whole erythrocytes Na+/K+-ATPase was only decreased in the regression phase. At high MgCl2 concentrations (12 mmol.l-1) changes of Na+/K+-ATPase activity both in whole erythrocytes and in the ghosts followed similar time course with a pronounced increase in the first phase of acclimatization (10 exposures) followed by an abrupt drop (24 exposures) and then by a gradual normalization in the regression phase. Sensitivity of the enzyme to mounting MgCl2 concentrations was increased in the ghosts at the end of acclimatization and was decreased in whole erythrocytes during acclimatization and especially in the regression phase. It has been suggested that chronic altitude hypoxia leads to the alteration of cooperative interaction of the Na+/K+-ATPase subunits in the erythrocyte membrane and accumulation of some factor in the cells inhibiting this enzyme.     

Infructescences of Friisicarpus nom. nov. (Platanaceae) and associated foliage of the platanoid type from the Cenomanian of western Siberia

A new generic name, Friisicarpus N. Maslova et Herman, is proposed to replace Platanocarpus Friis, Crane, et Pedersen, 1988. Pistillate capitate inflorescences of Friisicarpus nom. nov. are reported from the Cenomanian of western Siberia for the first time. They are found in association with leaves of the typical Platanus-morphotype. Earlier, remains belonging to this genus were found to be associated with pinnatifid leaves of cf. Sapindopsis variabilis Fontaine (Crane et al., 1993).     

Induction of the immunologic response in vitro

Immunological response (primary and secondary) was induced in a suspension of mouse splenic cells on nutrient media containing embryonic calf serum or serum against the erythrocytes of an animal--the lymphoid cells donor. The in vitro immunological response was accompanied by a specific increase in a number of the hemolysin-forming and rosette-forming cells. The optimal for induction of the immunological response in vitro was a dose of 10(7) erythrocytes per 1 ml of the culture. It was shown experimentally that antierythrocytic serum could be used instead of the embryonic calf serum to induce the immunological response in vitro. An increase in the count of rosette-forming cells and no increase of the hemolysin-forming cell count was observed on the nutrient media without 2-mercaptoethanol.