Body size is one of the most investigated traits in studies of sexual selection in fruit flies of the genus Drosophila. In D. melanogaster, size has often been correlated with male mating success, i.e. larger males were more successful in achieving copulations both in laboratory and field conditions. In the present paper, we investigated if male body size is a sexually selected trait in competitive conditions, when full-sibs that developed at two different temperatures (18 and 25°C) competed for females. Males developed at a lower temperature were significantly larger than those reared at a higher temperature, but they were not more successful in mating. We conclude that when body size is significantly induced by temperature variability, it is not correlated with male mating success., Sofija Pavkovic-Lučic, Vladimir Kekic., and Obsahuje seznam literatury
We have found that the determination of thiodiglycolic acid (TDGA) in urine may help to characterize metabolic imbalance of substances participating in methionine synthesis, which leads to hyperhomocystinuria. From the metabolic scheme, based on a proper combination of known facts, we attempted to theoretically explain and to demonstrate the possibilities of TDGA formation via different ways of homocysteine transformation. This scheme was used in evaluating the results obtained by testing urine of a woman suffering from impaired function of methionine synthase reductase (CblE type of homocystinuria). The amount of TDGA excreted in her morning urine was very sensitive to the changes in her treatment based upon a combination of N5-formyl tetrahydrofolate, betaine and vitamin B12. Vitamin B12 given in the evening either alone or together with betaine increased the TDGA excretion in the morning urine up to ten times. On the other hand, in the absence of vitamin B12, betaine in combination with N5-formyl tetrahydrofolate hindered the appearance of TDGA in the morning urine. Generally, the determination of TDGA in urine of an appropriately pretreated patient may indicate the degree of success of the treatment., T. Navrátil, M. Petr, Z. Šenholdová, K. Přistoupilová, T. I. Přistoupil, M. Heyrovský, D. Pelclová, E. Kohlíková., and Obsahuje bibliografii a bibliografické odkazy
The Asian ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is regarded as an invasive species in many parts of the world. In a previous study we hypothesised that H. axyridis enters diapause at the end of October and then shifts to a quiescent state in December in northwestern Europe. In the present study we test this idea of a short, early period of diapause by sampling beetles from their hibernation sites immediately after their migratory flights in October, subsequently keeping them in outdoor cages, and then, after certain time-intervals, measuring the pre-oviposition time under optimal egg-laying laboratory conditions at 25°C. We did this at both short (12L) and long (16L) photoperiods, since a photoperiodic response is an indicator of true diapause, rather than quiescence. A significant, albeit small, difference in pre-oviposition period between the two photoperiods, which disappears in December, corroborates our earlier hypothesis that the ladybirds are in a state of diapause until mid-December. Compared with that of native ladybirds the diapause of H. axyridis generally is relatively short and weak; moreover, it appears to have become shorter over the last decade. This flexibility in diapausing behaviour may be an important factor that contributes to the invasive success of H. axyridis., C. Lidwien Raak-Van Den Berg ... [et al.]., and Obsahuje seynam literatury
The size and fecundity of Hemiberlesia lataniae (Signoret) (Hemiptera: Diaspididae) on partially resistant and susceptible kiwifruit (Actinidia spp.) varieties was measured. The size ratio of mature H. lataniae grown on a partially resistant genotype, compared with those on a susceptible genotype, was 0.67-0.51 for 2nd instar exuviae area, 0.32 for adult body area and 0.18 for estimated body volume. The fertility ratio was 0.1, but the pre-oviposition period and the size of the crawlers were the same. Diaspidid scale insects' unusual ability to continue growing after the final moult appears to be a key feature allowing these insects to show extreme size plasticity while retaining the ability to reproduce even when very small. These observations challenge current theories of insect development that postulate the need to achieve a critical weight threshold before the final moult. We suggest that this strategy may have assisted the evolution of polyphagy within the Diaspididae. and M. Garry HILL, Rosa C. HENDERSON, Nicola A. MAUCHLINE.
Under normal conditions, antioxidants at the corneal surface are balanced with the production of reactive oxygen species without any toxic effects. Danger from oxidative stress appears when natural antioxidants are overwhelmed leading to antioxidant/prooxidant imbalance. The aim of the present study was to examine the activities of enzymes contributing to the antioxidant/prooxidant balance in normal corneal epithelium of various mammals. The enzyme activities of antioxidant superoxide dismutase and glutathione peroxidase, as well as prooxidant xanthine oxidoreductase/xanthine oxidase were examined using biochemical methods. Results show that superoxide dismutase activity is high in rabbits and guinea pigs, whereas in pigs the activity is low and in cows it is nearly absent. In contrast, glutathione peroxidase activity is high in cows, pigs and rabbits, whereas in guinea pigs the activity is low. As far as prooxidant enzymes are concerned, elevated xanthine oxidoreductase/xanthine oxidase activities were found in rabbits, lower activities in guinea pigs, very low activity in cows and no activity in pigs. In conclusion, the above results demonstrate inter-species variations in activities of enzymes participating in antioxidant/prooxidant balance in the corneal epithelium. It is suggested that the levels of antioxidant and prooxidant enzymes studied in the corneal epithelium might be associated with the diurnal or nocturnal activity of animals. UV rays decompose hydrogen peroxide to damaging hydroxyl radicals and perhaps for this reason large animals with diurnal activity (cow, pig) require more effective peroxide removal (high glutathione peroxidase activity) together with the suppression of peroxide production (low superoxide dismutase activity, low xanthine oxidoreductase activity)., J. Kovačeva, J. Pláteník, M. Vejražka, S. Štípek, T. Ardan, Č. Čejka, A. Midelfart, J. Čejková., and Obsahuje bibliografii a bibliografické odkazy
The use of light traps for controlling insect pests is restricted since they kill both pests and beneficial insects. It may be a possible to reduce the numbers of beneficial insects trapped by adjusting nightly trapping time based on differences recorded in the timing of the nocturnal flight peaks of target pests and beneficials. To test this, insects were collected hourly over night using black light traps at three locations in China from 2003 to 2005. Groups of lepidopteran and coleopteran pests were selected as the target pests that we would control by trapping and groups of beneficial predatory insects the catches of which needed to be reduced. The highest numbers of Coleoptera were caught between 20:00 and 22:00 h and of most Lepidoptera between 02:00 and 04:00 h. The hourly numbers of predatory insects caught by light traps were evenly distributed throughout the night. A model was developed to describe the relationships between the cumulative proportions of insects caught and time of night. The model accurately describes the flight activity of insects that were mainly caught before midnight, after midnight and evenly throughout a night by using different parameters for the three different insect groups. A beneficial-friendly trapping strategy was developed to reduce the numbers of beneficial insects trapped, which was based on differences in the nocturnal flight activity of pests and beneficial insects and validated by a field study in Shandong province. Results show that this trapping strategy reduced the number of beneficial insects caught by 46% and the electricity consumption by 50% compared to the traditional strategy. Thus this strategy is more beneficial-friendly than the traditional trapping strategy for controlling pests., Gang Ma, Chun-Sen Ma., and Obsahuje seznam literatury
Plant chemical composition is an important determinant of host plant-insect interactions. For many insects sugars are the main factors determining the acceptability of a plant. This study investigated changes in plant chemical composition and differences in sugar composition of different host plants induced by the feeding of Coccus hesperidum L. (Hemiptera: Sternorrhyncha: Coccoidea). Present in plant extracts and honeydew there were three monosaccharide sugars: glucose, fructose and arabinose, and one disaccharide - sucrose. Arabinose was only found in extracts of Ficus benjamina plants. The sugar content of the honeydew was greater than in the extracts of control plants and lower than that in the extracts of infested plants. The honeydew collected from C. hesperidum feeding on the three plant species differed significantly in sugar content. Extracts of coccid infested plants of the three species used in this study contained more sugar than the un-infested control plants. The results show that honeydew composition of scale insects differ and the differences reflect the chemical composition of the host plants. and Katarzyna Golan, Agnieszka Najda.
The objective of the present experiment was to assess the involvement of small intestine in expression of susceptibility or resistance to the high-fat/high-energy diet. The investigation was carried out in adult male Sprague-Dawley rats fed either standard laboratory diet (3.2 kcal/g, 9.5 % fat) or high-fat (HF) diet (4.04 kcal/g, 30 % fat) for 4 weeks as well as in HF rats that were retrospectively designated on the bases of their higher or lower weight gain as sensitive (DIO) or resistant (DR) to obesity. Our results revealed in HF group significant increase in energy intake, food efficiency, weight gain and Lee´s index of obesity. Moreover, in comparison with controls, a significantly increased duodenal and jejunal alkaline phosphatase (AP) and α-glucosidase activity as well as hypertrophy of jejunal mucosa (increased protein/DNA ratio) were observed in HF fed rats. In contrast, intestinal function was inversely related to energy intake or to the development of adiposity in DIO vs. DR rats. The DR rats had significantly greater AP and α-glucosidase activity and more pronounced suppression of energy intake than obese DIO rats. It indicates that the increase of enzyme activities and the lowered effectiveness of nutrient absorption might be a significant factor preventing the expression of obesity proneness. This information contributes to a better understanding of a complex interaction between HF diet feeding and small intestinal adaptability, which determines the energy homeostasis and predict the ability to resist or develop obesity in these phenotypes., Z. Šefčíková, T. Hájek, Ľ. Lenhardt, Ľ. Raček, Š. Možeš., and Obsahuje bibliografii a bibliografické odkazy
Objective of this study was to characterize osmotically-induced insulin secretion in two tumor cell lines. We compared response of freshly isolated rat pancreatic islets and INS-1 and INS-1E tumor cell lines to high glucose, 30 % hypotonic medium and 20 % hypertonic medium. In Ca2+-containing medium glucose induced insulin release in all three cell types. Hypotonicity induced insulin secretion from islets and INS-1 cells but not from INS-1E cells, in which secretion was inhibited despite similar increase in cell volume in both cell types. GdCl3 (100 μmol/l) did not affect insulin response from INS-1E cells to hypotonic challenge. Hypertonic medium inhibited glucose-induced insulin secretion from islets but not from tumor cells. Noradrenaline (1 μmol/l) inhibited glucose-induced but not swelling-induced insulin secretion from INS-1 cells. Surprisingly, perifusion with Ca2+-depleted medium showed distinct secretory response of INS-1E cells to hypotonicity while that of INS-1 cells was partially inhibited. Functioning glucose-induced insulin secretion is not sufficient prerequisite for hypotonicity-induced response in INS-1E cells suggesting that swelling-induced exocytosis is not essential step in the mechanism mediating glucose-induced insulin secretion. Both cell lines are resistant to inhibitory effect of hyperosmolarity on glucose-induced insulin secretion. Response of INS-1E cells to hypotonicity is inhibited by the presence of Ca2+ in medium., M. Orečná, R. Hafko, Z. Bačová, J. Podskočová, D. Chorvát Jr., V. Štrbák., and Obsahuje bibliografii a bibliografické odkazy
The pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae), is a well-studied species in terms of its colour polymorphism, where it occurs as two distinct colour morphs, red and green. It is proposed that the occurrence and maintenance of this polymorphism is an adaptive response to environmental factors, in particular natural enemies and host plant quality. We hypothesized that these adaptations are directly mirrored in the energy reserves accumulated by the different colour morphs during their pre-adult stages and reflect their specialization for particular ecological roles. We quantitatively measured the different energy reserves of red and green pea aphids and found that the total energy reserves of these morphs did not differ. Interestingly, these reserves were made up of different components in the red and green colour morphs. There was a higher percentage content of water-soluble carbohydrates and lipids in the red clones and higher percentage content of protein in green clones. These finding are in accordance with green clones being more fecund than red ones and needing more protein for reproduction than red clones, which produce more winged offspring when crowded or in response to the presence of natural enemies and so, need more lipids and carbohydrates to fuel their walking and flight. Apparently, different colour morphs are physiologically specialized to adjust their energy reserves in relation to their specific ecological adaptations and maximize their fitness in terms of dispersal, reproduction, defense and survival., Seyed Mohammad Ahsaei ... []., and Obsahuje seznam literatury