Reversible decreases in ATP and PCr concentrations in anoxic turtle brain

A hallmark of anoxia tolerance in western painted turtles is relative constancy of tissue adenylate concentrations during periods of oxygen limitation. During anoxia heart and brain intracellular compartments become more acidic and cellular energy demands are met by anaerobic glycolysis. Because changes in adenylates and pH during anoxic stress could represent important signals triggering metabolic and ion channel down-regulation we measured PCr, ATP and intracellular pH in turtle brain sheets throughout a 3-h anoxic-re-oxygenation transition with ³¹P NMR. Within 30 min of anoxia, PCr levels decrease 40% and remain at this level during anoxia. A different profile is observed for ATP, with a statistically significant decrease of 23% occurring gradually during 110 min of anoxic perfusion. Intracellular pH decreases significantly with the onset of anoxia, from 7.2 to 6.6 within 50 min. Upon re-oxygenation PCr, ATP and intracellular pH recover to pre-anoxic levels within 60 min. This is the first demonstration of a sustained reversible decrease in ATP levels with anoxia in turtle brain. The observed changes in pH and adenylates, and a probable concomitant increase in adenosine, may represent important metabolic signals during anoxia.     

和田皮墨垦区杨树十斑吉丁虫的生物学初报

杨十斑吉丁虫Melanophila picta Pallas是西北地区杨树的一种毁灭性蛀干害虫,近年杨十斑吉丁虫对和田皮墨垦区的杨树危害日益严重。对杨树十斑吉丁虫进行初步生物学研究表明,在和田皮墨垦区该虫1年发生1代,幼虫在树皮与木质间为害,造成杨树死亡。查清了该类害虫的为害时期及为害程度,其幼虫期人工刮皮消灭幼虫,成虫期树干涂沫2.5%高渗高效氯氰菊酯效果好。     

Parent–offspring conflict and selection on egg size in turtles

The trade‐off between offspring size and number can present a conflict between parents and their offspring. Because egg size is constrained by clutch size, the optimal egg size for offspring fitness may not always be equivalent to that which maximizes parental fitness. We evaluated selection on egg size in three turtle species (Apalone mutica, Chelydra serpentina and Chrysemys picta) to determine if optimal egg sizes differ between offspring and their mothers. Although hatching success was generally greater for larger eggs, the strength and form of selection varied. In most cases, the egg size that maximized offspring fitness was greater than that which maximized maternal fitness. Consistent with optimality theory, mean egg sizes in the populations were more similar to the egg sizes that maximized maternal fitness, rather than offspring fitness. These results provide evidence that selection has maximized maternal fitness to achieve an optimal balance between egg size and number.     

ELECTROPHORETIC AND IMMUNOLOGICAL STUDIES OF THE MALE ACCESSORY REPRODUCTIVE GLAND PROTEINS OF POECILOCERA PICTA FABR. (ACRIDIDAE: ORTHOPTERA)

Electrophoretic separation of the protein extracts of the whole accessory reproductive gland (ARG) reveals a progressive increase in number of fractions from day 0 to day 12 of adult life. The number of fractions secreted by the different types of tubules, viz., white tubules, hyaline tubules and seminal vesicles, varies. The protein concentration of the ARG of 12-day-old insects is four times higher than that of newly emerged adult insects. Three protein fractions of the ARG extract are immunologically precipitatale by antiserum to whole accessory gland complex. Immunoelectrophoresis of the oocyte extract from mated females and total protein extract of empty spermatophores revealed that one fraction of the oocyte protein and two of the spermatophores have their immunological counterparts in the whole ARG extract.     

Removal of diclofenac and sulfamethoxazole from synthetic municipal waste water in microcosm downflow constructed wetlands: Start-up results

The objectives of this study were to investigate the start-up removal of pharmaceutical compounds diclofenac and sulfamethoxazole in microcosm downflow constructed wetlands and their effect on the performance of the studied constructed wetlands, and also to assess the effect of plants on the removal of these compounds. The experimental system that was used in this 86-day experiment consisted of 24 columns filled up to 70 cm with predominantly sandy material. Four types of columns were used (six replicates) depending on the presence of plants (Phalaris arundinacea L. var. picta L.) and the presence of pharmaceutical compounds in the influent. The influent was synthetic municipal waste water to which a mixture of 5 mg/L of diclofenac and 5 mg/L of sulfamethoxazole was added. The observed removal of diclofenac was moderate (approx. 50%) and the removal of sulfamethoxazole was relatively low (24–30%). It was found that the removal of diclofenac and sulfamethoxazole was not affected by the vegetation. The presence of diclofenac and sulfamethoxazole in the influent had significant effect on the effluent concentration of N-NO₃ and the water loss in the columns, which in both cases were lower than in the control columns. The scope for further research was discussed.     

Mechanism and cost of synchronous hatching

1. Synchrony in the timing of births is thought to have evolved as a general predator avoidance strategy. In turtles, synchronous hatching may facilitate group emergence from the nest, which in turn, may limit predation by diluting an individual's risk of predation or by simply swamping predators upon emergence. However, synchronizing hatching should not be easily achieved in natural nests because of thermal gradients affecting developmental rates.
2. We evaluated pipping synchrony in the painted turtle ( Chrysemys picta ), where the drive to hatch synchronously may be reduced, because in many populations, hatching and emergence are dissociated through hatchlings overwintering within a nest.
3. We also assessed developmental mechanisms through which synchrony occurs and explored potential trade-offs between pipping synchrony and individual fitness by determining potential short and long-term neuromuscular developmental costs to hatching prematurely. These data were also used to develop a theoretical model to determine how differential embryonic maturation rates affect hatching synchrony.
4. Underdeveloped embryos pipped much earlier than expected and at similar times to their more advanced sibs. In addition, a trade-off between hatching synchronously and neuromuscular development (motility) was evident several days after hatching and up to 9 months later, after the overwintering period.
5. Synchronous hatching is an ancestral trait in turtles, but its relevance today is not solely for predator avoidance in all species.
6. Abiotic factors during incubation (e.g. temperature regime and moisture) have long-term effects on reptiles during ontogeny but it is also clear that incubation behaviour is major factor for the persistence of these developmental costs.     

Effective heritability of targets of sex-ratio selection under environmental sex determination

Selection is expected to maintain primary sex ratios at an evolutionary equilibrium. In organisms with temperature-dependent sex determination (TSD), targets of sex-ratio selection include the thermal sensitivity of the sex-determining pathway (hereafter, sex determination threshold) and nest-site choice. However, offspring sex may be canalized for nests located in thermally extreme environments; thus, genetic variance for the sex determination threshold is not expressed and is invisible to direct selection. The concept of 'effective heritability' accounts for this dependence and provides a more realistic prediction of the expected evolutionary response to selection in the wild. Past estimates of effective heritability of the sex determination threshold, which were derived from laboratory data, suggested that the potential for the sex determination threshold to evolve in the wild was extremely low. We re-evaluated original estimates of this parameter by analysing field-collected measures of nest temperatures, vegetation cover and clutch sex ratios from nests in a population of painted turtles (Chrysemys picta). We coupled these data with measurements of broad-sense heritability of the sex determination threshold in C. picta, using an experiment that splits clutches of eggs between a constant temperature (i.e. typical laboratory incubation) and a daily fluctuating temperature (i.e. similar to natural nests) with the same mean. We found that (i) the effective heritability of the sex determination threshold appears to have been historically underestimated and the effective heritability of nest-site choice has been overestimated and (ii) significant family-by-incubation treatment interaction exists for sex for C. picta between constant- and fluctuating-temperature regimes. Our results suggest that the thermal sensitivity of the sex-determining pathway may play a larger, more complex role in the microevolution of TSD than traditionally thought.     

Sources of protein in two semi‐arid zone mistletoe specialists: Insights from stable isotopes

Obtaining adequate levels of dietary protein is essential for the physiology of consumers. This presents potential problems for frugivorous birds because fruit is generally low in protein rendering it nutritionally inadequate and potentially explaining the rarity of exclusive frugivory in birds. We addressed this issue by determining the isotope composition (¹⁵N/¹⁴N) in the whole blood of two mistletoe consumers, that is, painted honeyeater (Grantiella picta, Meliphagidae) and mistletoebird (Dicaeum hirundinaceum, Dicaeidae) during the grey mistletoe (Amyema quandang, Loranthaceae) fruiting peak in a semi‐arid woodland, NSW, Australia. Grey mistletoe fruit pulp and arthropods were isotopically distinct (mean δ¹⁵N fruit 4.4‰vs. arthropods 7.1‰), thus readily discriminated using the stable isotope approach. Painted honeyeaters and mistletoebirds formed a single group based on their mean δ¹⁵N values and, on average, assimilated approximately half of their nitrogen from mistletoe fruit although individual variation was high. The importance of nitrogen derived from mistletoe fruit did not track its abundance in the environment, suggesting that at least during peak fruiting, this resource is not limiting at this site. Researchers should account for intraspecific variation and take a cautious approach when reconstructing diets using stable isotopes by incorporating individual‐based analyses rather than presenting mean values alone. This is the first study to use the isotope approach to investigate the dietary relationship of mistletoe frugivores and mistletoe fruit and has implications for our understanding of the nutritional ecology of frugivores and its functional relationship to ecosystem processes such as seed dispersal.