Temperaturregulation bei Flughunden der Gattung Rousettus Gray

Summary The ability to regulate body temperature was studied in the fruitbat Rousettus aegyptiacus. The daily range of body temperature (37,0–41,1°C) is much smaller than that of several Microchiroptera of the temperate zones. Considerable variations of ambient temperature within 24 hours (0–41°C) has no noticible influence on the body temperature of the fruitbat. During periods of low temperature the fruitbat becomes inactive but not torpid or lethargic. Only prolonged exposure to low temperature leads to hypothermia, especially in young animals. Sufficient nutrition delays entry into the hypothermic state. Deep hypothermia is reversible only by artificial rewarming. The fruitbats are unable to rewarm themselves neither spontanously nor after mechanical stimulation. In hypothermia temperature regulation breaks down. Body temperatures of 15°C are already lethal. The fruitbat can endure the hypothermic state only for a short time. The animals respond to low temperature with shivering and increased respiration like other homoiothermic animals. Hypothermia was induced artificially in the fruitbat; it is not a torpid or lethargic state as in the Microchiroptera of the temperate zones. Fruitbats of the genus Rousettus are homeothermic animals; they regulate their body temperatures against both heat and cold. From this study and other data we may conclude that thermoregulation in Megachiroptera differs considerably from many species of Microchiroptera, which become heterothermic when exposed to cold.

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Die Arbeit wurde gefördert durch Mittel der Deutschen Forschungsgemeinschaft, die mir durch Herrn Prof. Dr. Möhres zur Verfügung standen. Für viele Anregungen danke ich herzlich Herrn Prof. Möhres, für unersetzliche Hilfe in Afrika Dr. H. Hoogstraal vom U.S. NAMRU 3 in Kairo.     

Morphologische Betrachtungen über Skelettelemente der Coccolithineen

Ohne Zusammenfassung     

Polaritätsstörungen bei Pflanzenzellen durch Äthylen

Zusammenfassung Durch Äthylen wird die radiale Polarität im Sproß vonVicia faba gestört. Es treten 2 Endodermen, eine davon zwischen den Gefäßbündeln und dem inneren Teil des Marks, auf. Auch ein zweites, Seitenwurzeln bildendes Perizykelgewebe entsteht. Die Kutinisierung der Membranen im Bereich der Endodermen kann infolge der gestörten radialen Polarität völlig diffus werden und sich sogar auf Markzellen ausdehnen. Die auch sonst allgemein mit Polaritätsverlust verbundene Embryonalisierung äußert sich in dichten Zellwucherungen im Mark.Mit 6 Textabbildungen.     

Eine Wirkung von Chloralhydrat auf Spirillen

Ohne Zusammenfassung     

Über die histologischen Vorgänge bei der Regeneration von Tritonen mit Beteiligung ortsfremder Haut

Ohne ZusammenfassungDa ich kurz vor meiner Übersiedelung nach Riga stehe, um einem Rufe an das deutsche Herderinstitut zu folgen, sehe ich mich genötigt, die Resultate meiner Untersuchungen schon jetzt zu veröffentlichen, obgleich manches noch zu vervollständigen wäre. So konnte unter anderem auf die interessante Frage der Entstehung und der Verteilung des Pigmentes, für die aber noch eine Reihe zeitraubender Experimente nötig gewesen wäre, nicht näher eingegangen werden.     

Quantitative trait loci involved in the reproductive success of a parasitoid wasp

Dissecting the genetic basis of intraspecific variations in life history traits is essential to understand their evolution, notably for potential biocontrol agents. Such variations are observed in the endoparasitoid Cotesia typhae (Hymenoptera: Braconidae), specialized on the pest Sesamia nonagrioides (Lepidoptera: Noctuidae). Previously, we identified two strains of C. typhae that differed significantly for life history traits on an allopatric host population. To investigate the genetic basis underlying these phenotypic differences, we used a quantitative trait locus (QTL) approach based on restriction site‐associated DNA markers. The characteristic of C. typhae reproduction allowed us generating sisters sharing almost the same genetic content, named clonal sibship. Crosses between individuals from the two strains were performed to generate F2 and F8 recombinant CSS. The genotypes of 181 clonal sibships were determined as well as the phenotypes of the corresponding 4,000 females. Informative markers were then used to build a high‐quality genetic map. These 465 markers spanned a total length of 1,300 cM and were organized in 10 linkage groups which corresponded to the number of C. typhae chromosomes. Three QTLs were detected for parasitism success and two for offspring number, while none were identified for sex ratio. The QTLs explained, respectively, 27.7% and 24.5% of the phenotypic variation observed. The gene content of the genomic intervals was investigated based on the genome of C. congregata and revealed 67 interesting candidates, as potentially involved in the studied traits, including components of the venom and of the symbiotic virus (bracovirus) shown to be necessary for parasitism success in related wasps.     

ABA and BAP improve the accumulation of carbohydrates and alter carbon allocation in potato plants at elevated CO2

Elevated CO₂ interactions with other factors affects the plant performance. Regarding the differences between cultivars in response to CO₂ concentrations, identifying the cultivars that better respond to such conditions would maximize their potential benefits. Increasing the ability of plants to benefit more from elevated CO₂ levels alleviates the adverse effects of photoassimilate accumulation on photosynthesis and increases the productivity of plants. Despite its agronomic importance, there is no information about the interactive effects of elevated CO₂ concentration and plant growth regulators (PGRs) on potato (Solanum tuberosum L.) plants. Hence, the physiological response and source-sink relationship of potato plants (cvs. Agria and Fontane) to combined application of CO₂ levels (400 vs. 800 µmol mol⁻¹) and plant growth regulators (PGR) [6-benzylaminopurine (BAP) + Abscisic acid (ABA)] were evaluated under a controlled environment. The results revealed a variation between the potato cultivars in response to a combination of PGRs and CO₂ levels. Cultivars were different in leaf chlorophyll content; Agria had higher chlorophyll a, b, and total chlorophyll content by 23, 43, and 23%, respectively, compared with Fontane. The net photosynthetic rate was doubled at the elevated compared with the ambient CO₂. In Agria, the ratio of leaf intercellular to ambient air CO₂ concentrations [C_i:C_a] was declined in elevated-CO₂-grown plants, which indicated the stomata would become more conservative at higher CO₂ levels. On the other hand, the increased C_i:C_a in Fontane showed a stomatal acclimation to higher CO₂ concentration. The higher leaf dark respiration of the elevated CO₂-grown and BAP + ABA-treated plants was associated with a higher leaf soluble carbohydrates and starch content. Elevated CO₂ and BAP + ABA shifted the dry matter partitioning to the belowground more than the above-media organs. The lower leaf soluble carbohydrate content and greater tuber yield in Fontane might indicate a more efficient photoassimilate translocation than Agria. The results highlighted positive synergic effects of the combined BAP + ABA and elevated CO₂ on tuber yield and productivity of the potato plants.     

Exercise training and oxidative stress in the elderly as measured by antipyrine hydroxylation products

Effects of 12 wk exercise training on oxidative stress were examined in elderly humans. We measured oxidative stress during a 45 min cycling test by using antipyrine hydroxylation products. Antipyrine breakdown is independent of blood flow to the liver, which is important during exercise. Furthermore, antipyrine reacts quickly with hydroxyl radicals to form para- and ortho-hydroxyantipyrine. Ortho-hydroxyantipyrine is not formed in man through the mono-oxygenase pathway of cytochrome P450. Twenty subjects (9 women; 60 ± 3 y) participated in the training program. Thirteen subjects (5 women; 64 ± 7 y) served as inactive controls. Subjects trained, twice a week for 1h, at a fitness center. After 12 wk, maximal oxygen uptake (p < .005) and workload capacity (p < .001) were only significantly elevated in the training group. After 12 wk, both groups observed no change in the ratios of antipyrine hydroxylates, para- and ortho-hydroxy-antipyrine, to native antipyrine. Furthermore, no differences were observed within or between groups in the exercise-induced increase in the plasma level of thiobarbituric acid reactive species. In conclusion, 12-wk training had no effect on exercise-induced oxidative stress in elderly humans as measured by free radical reaction products of antipyrine. Despite the fact that training in elderly humans improves functional capacity, it appears not to compromise antioxidant defense mechanisms.