Behavior of crested auklets (<Emphasis Type="Italic">Aethia cristatella</Emphasis>, Charadriiformes,Alcidae) in the breeding season: Visual and acoustic displays

The crested auklet, a highly social planktivorous bird species of the Northern Pacific, is an important component of marine ecosystems. Although visual and acoustic modalities play a major role in the communication of these birds, the available data on the repertoire of their vocal signals and postures are scarce and lack quantitative analysis. This study deals with visual and acoustic displays of crested auklets on their breeding grounds and the occurrence frequencies of certain forms of social behavior in male and female birds. The data were collected on Talan Island (the Sea of Okhotsk) in 1987–1991 and 2008. They show that the rate of contacts between birds is very high and sex-specific: on average, males initiate 1.13 contacts/min, compared to 0.65 contacts/min initiated by females. Directionality of ruff-sniff displays differs depending on the posture of the recipient bird. The duration of the trumpeting display in males depends on their social surroundings. However, the duration of either the trumpeting display or the mutual cackling display during courtship is independent of the behavioral context. Vocalization of crested auklets is characterized by two independent basic frequencies occurring either sequentially or simultaneously. The role of different communicative modalities in the behavior of the crested auklet is discussed.     

Melatonin directly scavenges free radicals generated in red blood cells and a cell-free system: chemiluminescence measurements and theoretical calculations

Melatonin, a pineal secretory product, has properties of both direct and indirect powerful antioxidant. The aim of the present study was to compare the radical-scavenging, structural and electronic properties of melatonin and tryptophan, precursor of melatonin. Using the alkoxyl- and peroxyl radical-generating systems [the organic peroxide-treated human erythrocytes and a cell-free system containing the azo-initiator 2,2'-azobis(2-amidinopropane)dihydrochloride], we evaluated the radical-scavenging effects of melatonin and tryptophan. Melatonin rather than tryptophan at concentrations of 100-2000 microM markedly inhibited membrane lipid peroxidation in human erythrocytes treated with organic hydroperoxide as well as radical-induced generation of luminol-dependent chemiluminescence. The apparent Stern-Volmer constants for inhibition of membrane lipid peroxidation by melatonin and tryptophan were estimated to be (0.23+/-0.05) x 10(4) M(-1) and (0.02+/-0.005) x 10(4) M(-1), respectively. The apparent Stern-Volmer constants for inhibition of azo-initiator-derived peroxyl radical generation by melatonin and tryptophan were determined to be (0.42+/-0.05) x 10(4) M(-1) and (0.04+/-0.01) x 10(4) M(-1), respectively. The structural and electronic properties of melatonin and its precursor, tryptophan, were determined theoretically by performing semi-empirical and ab initio calculations. The high radical-scavenging properties of melatonin may be explained by the high surface area value and high dipole moment value. From the thermodynamic standpoint, based on our calculations, N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK), was the most stable end oxidative product of melatonin.     

Glucose-regulated protein Grp78 affects characteristics of sleep and thermoregulation in rats

It was shown previously that sleep deprivation in representatives of warm-blooded animals evokes an elevation of the glucose-regulated protein 78 (Grp78) gene expression in the brain structures involved in the control of sleep and thermoregulation. However it is currently unknown what role the increased Grp78 expression plays in the mechanisms that maintain homeostasis of sleep and thermoregulation. Using electrophysiological methods, it has been shown in this study that microinjections of Grp78 into the third brain ventricle of Wistar rats evokes an increase mostly in deep non-rapid-eye-movement (NREM) sleep (due to a lengthening of the NREM sleep episodes) and a decrease in the amount of rapid-eye-movement sleep. The period of deep NREM sleep was accompanied by a reduced muscle contractile activity. Our results provide evidence that Grp78 is implicated in the molecular mechanisms of maintenance of deep NREM sleep typically accompanied by a decrease in muscle contractile activity.     

A subset of cells in tobacco mosaic virus (TMV)-induced local lesions in <Emphasis Type=Italic>Datura stramonium</Emphasis> leaves are tolerant to TMV

Ultrastructural examination of tobacco mosaic virus-induced local lesions growing in Datura stramonium leaves is carried out. It is demonstrated that, in the central area of the lesions, the cell response to viral invasion is not uniform. Most cells exhibited an acute hypersensitive reaction (HR) and underwent rapid and complete necrosis. However, some cells, despite considerable virus accumulation and immediate contact with completely collapsed cells, maintained a certain degree of structural integrity. Analysis performed showed that the proportion of collapsed and uncollapsed cells in the lesion centre 3 to 5 days after infection essentially did not change. These data suggest that the absence of HR in some cells in the lesion centre is not due to an early stage of infection but is likely caused by cell tolerance of the virus.     

Protection of transgenic tobacco plants expressing bovine pancreatic ribonuclease against tobacco mosaic virus

Transgenic tobacco plants (Nicotiana tabacum cv. SR1) expressing extracellular pancreatic ribonuclease from Bos taurus and characterized by an increased level of ribonuclease activity in leaf extracts were challenged with tobacco mosaic virus. The transgenic plants exhibited a significantly higher level of protection against the virus infection than the control non-transformed plants. The protection was evidenced by the absence (or significant delay) of the appearance of typical mosaic symptoms and the retarded accumulation of infectious virus and viral antigen. These results demonstrate that modulation of extracellular nuclease expression can be efficiently used in promoting protection against viral diseases.     

Study of protective effects of exogenous heat shock protein 70 kDa in model of sleep deprivation in pigeon <Emphasis Type=Italic>Columba livia</Emphasis>

Electroencephalographic methods were used to study effects of preparation of the exogenous heat shock protein with molecular mass of 70 kDa (Hsp70i/Hsc70) on time characteristics of sleep and wakefulness, brain temperature, peripheral vasomotor reactions, and thoracic muscle contractile activity after the 5-hour forceful sleep deprivation in the pigeon Columba livia. Administration of Hsp70i/Hsc70 into the third brain ventricle at once after the end of sleep deprivation eliminated disturbances in the sleep-wakefulness cycle organization and decreased the thoracic muscle contractile activity and the brain temperature as early as for the first hour of postdeprivation period. For the subsequent hours, the Hsp70i/Hsc70 action was characterized by an increase of the total time of deep sleep and a decrease of the total time of the rapid eye movement sleep. We suggest that the protective effects of the exogenous Hsp70i/Hsc70 preparation are associated with its ability to decrease activity of the hypothalamo-pituitary-adrenal axis and to enhance the stress-limiting function of the slow eye movement sleep.     

Correlation between influence of polysaccharides on hydrolase activity and their antiviral effect in tobacco leaves

The activities of hydrolases (acid phosphatase, RNase, and proteases) in healthy and tobacco mosaic virus-infected leaves of Nicotiana tabacum L. var. Samsun, both untreated and treated with polysaccharides (PS) (1,3;1,6-β-D-glucan, fucoidan, and κ/β-carrageenan), were determined. The PS lead to substantial increase in the hydrolase level. The percentage of viral particles undergoing destructive change also increases in leaves treated with PS 24 h before infection. We suppose that the PS-mediated hydrolase activation promotes intracellular destruction of the viral particles and, thus, comprises one of the PS-induced protective mechanisms limiting intracellular viral accumulation.     

Melatonin and succinate reduce rat liver mitochondrial dysfunction in diabetes

Mitochondrial dysfunction and an increase in mitochondrial reactive oxygen species in response to hyperglycemia during diabetes lead to pathological consequences of hyperglycemia. The aim of the present work was to investigate the role of a specific functional damage in rat liver mitochondria during diabetes as well as to evaluate the possibility of metabolic and antioxidative correction of mitochondrial disorders by pharmacological doses of succinate and melatonin. In rat liver mitochondria, streptozotocin-induced diabetes was accompanied by marked impairments of metabolism: we observed a significant activation of α-ketoglutarate dehydrogenase (by 60%, p<0.05) and a damage of the respiratory function. In diabetic animals, melatonin (10 mg/kg b.w., 30 days) or succinate (50 mg/kg b.w., 30 days) reversed the oxygen consumption rate V(3) and the acceptor control ratio to those in nondiabetic animals. Melatonin enhanced the inhibited activity of catalase in the cytoplasm of liver cells and prevented mitochondrial glutathione-S-transferase inhibition while succinate administration prevented α-ketoglutarate dehydrogenase activation. The mitochondria dysfunction associated with diabetes was partially remedied by succinate or melatonin administration. Thus, these molecules may have benefits for the treatment of diabetes. The protective mechanism may be related to improvements in mitochondrial physiology and the antioxidative status of cells.     

Ultrastructure and hydrolase activity in tobacco leaves exposed to chitosan

The mesophyll ultrastructure and hydrolase activity in leaves of tobacco cv. Samsun exposed to chitosan were studied. It was shown that, in many cells, chitosan treatment stimulated the protein-synthesizing apparatus (nucleolus size and amount of both mitochondria and membranes of rough endoplasmic reticulum increased). At the same time, we observed activation of the lytic compartment displayed as stimulated production of dictyosomes, smooth ER elements, and cytoplasmic vacuoles, which are prominent constituents of this compartment. Biochemical experiments showed that, in the leaves, chitosan substantially enhanced activity of hydrolases (acid phosphatase, RNase, proteases) as compared to untreated leaves. In some cells, chitosan treatment caused considerable destructive changes (condensation of nuclear chromatin, collapse of cytoplasm, etc.) that can be classified as development of programmed cell death.