Effects of diet and water supply on energy intake and water loss in a mygalomorph spider in a fluctuating environment of the central Andes

The metabolic and water evaporation strategies in spiders may be part of a set of physiological adaptations to tolerate low or unpredictable food availability, buffering spiders against environmental fluctuations such as those of the high mountains of the central Andes.The aim of this study is to analyze experimentally the variations in metabolic rate and the rate of evaporative water with food and/or water restriction in a high mountain mygalomorph spider population (Paraphysa sp.).We found that the low metabolism of this spider was not affected by water restriction, but its metabolism was depressed after 3 weeks of food deprivation. The spider did not show seasonal metabolic changes but it presented seasonal changes in the rate of evaporative water loss at high temperatures.Females with egg sacs reduced their metabolic rate and evaporative water at high temperatures.These findings constitute a set of possible adaptations to a highly fluctuating Mediterranean environment, which is completely covered with snow for many months and then progresses rapidly to a very dry climate with high temperatures.     

Effects of meal size, clutch, and metabolism on the energy efficiencies of juvenile Burmese pythons, Python molurus

We explored meal size and clutch (i.e., genetic) effects on the relative proportion of ingested energy that is absorbed by the gut (apparent digestive efficiency), becomes available for metabolism and growth (apparent assimilation efficiency), and is used for growth (production efficiency) for juvenile Burmese pythons (Python molurus). Sibling pythons were fed rodent meals equaling 15%, 25%, and 35% of their body mass and individuals from five different clutches were fed rodent meals equaling 25% of their body mass. For each of 11–12 consecutive feeding trials, python body mass was recorded and feces and urate of each snake was collected, dried, and weighed. Energy contents of meals (mice and rats), feces, urate, and pythons were determined using bomb calorimetry. For siblings fed three different meal sizes, growth rate increased with larger meals, but there was no significant variation among the meal sizes for any of the calculated energy efficiencies. Among the three meal sizes, apparent digestive efficiency, apparent assimilation efficiency, and production efficiency averaged 91.0%, 84.7%, and 40.7%, respectively. In contrast, each of these energy efficiencies varied significantly among the five different clutches. Among these clutches production efficiency was negatively correlated with standard metabolic rate (SMR). Clutches containing individuals with low SMR were therefore able to allocate more of ingested energy into growth.     

Identification and characterization of oxalate oxidoreductase, a novel thiamine pyrophosphate-dependent 2-oxoacid oxidoreductase that enables anaerobic growth on oxalate

Moorella thermoacetica is an anaerobic acetogen, a class of bacteria that is found in the soil, the animal gastrointestinal tract, and the rumen. This organism engages the Wood-Ljungdahl pathway of anaerobic CO(2) fixation for heterotrophic or autotrophic growth. This paper describes a novel enzyme, oxalate oxidoreductase (OOR), that enables M. thermoacetica to grow on oxalate, which is produced in soil and is a common component of kidney stones. Exposure to oxalate leads to the induction of three proteins that are subunits of OOR, which oxidizes oxalate coupled to the production of two electrons and CO(2) or bicarbonate. Like other members of the 2-oxoacid:ferredoxin oxidoreductase family, OOR contains thiamine pyrophosphate and three [Fe(4)S(4)] clusters. However, unlike previously characterized members of this family, OOR does not use coenzyme A as a substrate. Oxalate is oxidized with a k(cat) of 0.09 s(-1) and a K(m) of 58 μM at pH 8. OOR also oxidizes a few other 2-oxoacids (which do not induce OOR) also without any requirement for CoA. The enzyme transfers its reducing equivalents to a broad range of electron acceptors, including ferredoxin and the nickel-dependent carbon monoxide dehydrogenase. In conjunction with the well characterized Wood-Ljungdahl pathway, OOR should be sufficient for oxalate metabolism by M. thermoacetica, and it constitutes a novel pathway for oxalate metabolism.     

Sorting out the effects of Wolbachia, genotype and inbreeding on life-history traits of a spider mite

Wolbachia bacteria manipulate host reproduction by inducing cytoplasmic incompatibility (CI) and sex ratio distortion. Wolbachia are transmitted from mother to offspring through the cytoplasm of the egg. Therefore, reproduction of Wolbachia is tightly coupled to reproduction of its host. Mathematical analysis predicts that in the course of evolution, traits that reduce the physiological costs of the infection will be selectively favored. For a Wolbachia-host system to evolve, traits under selection must have some genetic component and variation must be present in the population. We have previously established that highly inbred isofemale lines of the two-spotted spider mite Tetranychus urticae may differ regarding the effects of infection by Wolbachia, and that at least some of the traits affected had a genetic component. However, the effects measured could have been affected by the fact that the lines were severely inbred prior to the experiments. In this paper we attempt to distinguish between the effects of Wolbachia, isofemale line, and inbreeding. We show that Wolbachia did not affect longevity but infected females produced smaller clutch sizes, more daughter-biased sex ratios and had decreased F1 mortality; between-line variation was found for clutch size, F1 mortality and sex ratio; finally, inbreeding resulted in an overall reduction of clutch sizes, and a change in survival curves and mean longevity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bias, precision and accuracy in the estimation of cuticular and respiratory water loss: a case study from a highly variable cockroach, Perisphaeria sp

We compared the precision, bias and accuracy of two techniques that were recently proposed to estimate the contributions of cuticular and respiratory water loss to total water loss in insects. We performed measurements of VCO2 and VH2O in normoxia, hyperoxia and anoxia using flow through respirometry on single individuals of the highly variable cockroach Perisphaeria sp. to compare estimates of cuticular and respiratory water loss (CWL and RWL) obtained by the VH2O-VCO2 y-intercept method with those obtained by the hyperoxic switch method. Precision was determined by assessing the repeatability of values obtained whereas bias was assessed by comparing the methods' results to each other and to values for other species found in the literature. We found that CWL was highly repeatable by both methods (R0.88) and resulted in similar values to measures of CWL determined during the closed-phase of discontinuous gas exchange (DGE). Repeatability of RWL was much lower (R=0.40) and significant only in the case of the hyperoxic method. RWL derived from the hyperoxic method is higher (by 0.044 micromol min(-1)) than that obtained from the method traditionally used for measuring water loss during the closed-phase of DGE, suggesting that in the past RWL may have been underestimated. The very low cuticular permeability of this species (3.88 microg cm(-2) h(-1) Torr(-1)) is reasonable given the seasonally hot and dry habitat where it lives. We also tested the hygric hypothesis proposed to account for the evolution of discontinuous gas exchange cycles and found no effect of respiratory pattern on RWL, although the ratio of mean VH2O to VCO2 was higher for continuous patterns compared with discontinuous ones.     

Theoretical studies on the crystal structure, thermodynamic properties, detonation performance and thermal stability of cage-tetranitrotetraazabicyclooctane as a novel high energy density compound

The B3LYP/6-31G (d) method of density functional theory (DFT) was used to study molecular geometry, electronic structure, infrared spectrum (IR) and thermodynamic properties. The heat of formation (HOF) and calculated density were estimated to evaluate the detonation properties using Kamlet–Jacobs equations. Thermal stability of 3,5,7,10,12,14,15,16-octanitro- 3,5,7,10,12,14,15,16-octaaza-heptacyclo[7.5.1.1^2,8.0^1,11.0^2,6.0^4,13.0^6,11]hexadecane (cage-tetranitrotetraazabicyclooctane) was investigated by calculating the bond dissociation energy (BDE) at unrestricted B3LYP/6-31G (d) level. The calculated results show that the N–NO₂ bond is a trigger bond during thermolysis initiation process. The crystal structure obtained by molecular mechanics (MM) methods belongs to Pna2₁ space group, with cell parameters a?=?12.840 Å, b?=?9.129 Å, c?=?14.346 Å, Z?=?6 and ρ?=?2.292 g·cm^?3. Both the detonation velocity of 9.96 km·s^?1 and the detonation pressure of 47.47 GPa are better than those of CL-20. According to the quantitative standard of energetics and stability, as a high energy density compound (HEDC), cage-tetranitrotetraazabicyclooctane essentially satisfies this requirement.     

In situ studies on AMP deaminase as a control system of the adenylate energy charge in yeasts

The role of AMP deaminase reaction in the stabilization of the adenylate energy charge was investigated using permeabilized yeast cells. The addition of P_i or Zn²⁺, which inhibits AMP deaminase, remarkably retarded the depletion of total adenylate pool and the recovery of the adenylate energy charge. Polyamine, an activator of the enzyme, decreased total adenylates, resulting in the enhanced recovery of the energy charge in situ. AMP deaminase can act as a regulatory enzyme in the system that stabilizes the adenylate energy charge in yeast cells under the conditions of severe metabolic stress.     

Biological studies of the predacious miteTyphlodromus pelargonicus a predator of the two spotted spider miteTetranychus urticae on cucumber plants [Acari: Phytoseiidae; Tetranychidae]

The predacious miteTyphlodromus pelargonicus El-Badry preyed on the different developmental stages of the two spotted spider miteTetranychus urticae Koch. The development was quickest and the number of prey consumed was highest when individuals were maintained on eggs compared with nymphs or adult female stages. The predator was able to develop and reproduce on the eriophyid miteEriophyes dioscoridis. Soliman & Abou-Awad, nymphs of the tobacco whiteflyBemisia tabaci (Genn.) and pollen grains ofPhoenix dactylifera andRicinus communis. The average number of eggs/♀/day was 1.4, 0.7, 1.2 and 0.9 on eriophyid, whitefly,Ph. dactylifera andR. communis respectively.      

The effect of a single colony of the red wood ant,Formica polyctena,on the spider fauna (Araneae) of a beech forest floor

Summary The predation on spiders in a forest ecosystem by a colony of red wood ants, Formica polyctena, was estimated using a barrier to isolate the colony. Of the ants' total prey, 4.6% were spiders. In order to estimate the effect of F. polyctena within their hunting area on the spider population, the spiders' population density was studied inside and outside the hunting area. Samples of the forest floor were taken, spider webs were counted and pitfall traps were used. No significant difference was found in density or composition of the spider fauna inside and outside the hunting area.     

Effects of chronic administration of a heme oxygenase substrate or inhibitor on progression of the estrous cycle,pregnancy and lactation of Sprague-Dawley rats

The purpose of this study was to investigate whether a heme oxygenase substrate (hemin) or an inhibitor (chromium mesoporphyrin IX; CrMP) had any effect on the normal course of the estrous cycle, pregnancy, parturition or lactation in rats. The hypothesis was that these agents, acting on HO to increase or decrease endogenous production of carbon monoxide (CO) respectively, would disrupt these reproductive processes. The results showed that hemin administered s.c. at 30 micromoles/kg for 10 or 11 days, did not markedly influence the estrous cycle; whereas CrMP blocked the estrous cycle in a dose dependant fashion. At 2 and 4 micromoles/kg for 11 days CrMP significantly reduced the occurrence of estrus phase of the estrous cycle and the effect continued after the treatments were discontinued, while a dose of 1 micromole/kg produced no significant effects. CrMP, administered at 4 micromoles/kg during days 5-14 of pregnancy, led to massive fetal resorption with no live births from 14 successfully mated rats. Administration of hemin at 30 micromoles/kg for 10 days during lactation did not have any effect on milk production, whereas administration of CrMP at 4 micromoles/kg significantly decreased lactational performance which was attributed to milk production and not to suckling intensity of the pups. From these observations we conclude that heme oxygenase, and presumably endogenous CO, play positive roles in female reproductive processes and lactation in the rat.     

Preliminary studies on the induction of a 120 000 molecular weight protein in resident peritoneal macrophages by arachidonic acid

Exogenous arachidonic acid induced the synthesis of a 120 000 molecular weight protein in resident peritoneal macrophages. The induction of this protein is specific to the presence of arachidonic acid in the culture medium and is not induced by the presence of other fatty acids, irrespective of their chain length or degree of unsaturation. The protein induced is not a secretory protein and is not formed as a result of the processing of preexisting proteins in macrophages. In addition to arachidonic acid, prostaglandin E₂ also induced the synthesis of 120 000 molecular weight protein in macrophages.     

利用马尾松年轮资料重建江苏暖湿地区气候的初步研究

利用树木年轮气候学方法,根据马尾松生长对气候变量具非线性响应,尝试重建江苏暖湿地区过去１１６年（１８７４～１９９０）的年平均气温和降水量。温度的重建效果优于降水量,实测值与重建值两者的缩减误差（ＲＥ）分别为０．１２和０．１０,两者的平均偏差百分率分别为２．３％和２０％。绝大部分重建结果可从观测记录和历史文献中得到验证,但在温度较高或降水量较多的若干年份,实测值与重建值有较大偏差。     

Experiments on the physiology of southern and northern krill, Euphausia superba and Meganyctiphanes norvegica, with emphasis on moult and growth - a review

Physiological data are needed for life history studies on krill, and as parameters for input into energy budgets and models. In conjunction with moult and growth data, these may also prove useful for assessing the fishable biomass of krill. Here, the development of physiological concepts in experimental krill research is briefly evaluated, with emphasis on the gaps to be filled. Krill growth is very flexible, as well as strongly temperature and nutrition dependent. The polar Antarctic krill Euphausia superba grows as fast as the boreal species Meganyctiphanes norvegica, at least during the first 2.5 years, and the species are comparable in terms of physiological plasticity. Accordingly, as krill appear to adjust quickly to specific laboratory conditions, short-term experiments are essential if field conditions are to be reflected as closely as possible. Furthermore, direct comparisons between laboratory experiments and swarming studies in the field are advantageous. For these, M. norvegica is particularly well-suited, as swarms can be followed over longer times and more easily than in E. superba. For example, processes of moult and reproduction were found to be highly coordinated in swarms and populations of Northern krill. For this species a conceptual model of reproduction was developed based on a combination of short-term laboratory observations coupled with field data on moult and ovary stages. In further physiological experiments krill should be studied as groups when swarming. Using proxies, that is applying physiological and/or biochemical methods side by side, is a promising way to enhance the reliability of life history data.     

Estimation of photosynthesis and calcification rates at a fringing reef by accounting for diurnal variations and the zonation of coral reef communities on reef flat and slope: a case study for the Shiraho reef, Ishigaki Island, southwest Japan

Seven coral reef communities were defined on Shiraho fringing reef, Ishigaki Island, Japan. Net photosynthesis and calcification rates were measured by in situ incubations at 10 sites that included six of the defined communities, and which occupied most of the area on the reef flat and slope. Net photosynthesis on the reef flat was positive overall, but the reef flat acts as a source for atmospheric CO₂, because the measured calcification/photosynthesis ratio of 2.5 is greater than the critical ratio of 1.67. Net photosynthesis on the reef slope was negative. Almost all excess organic production from the reef flat is expected to be effused to the outer reef and consumed by the communities there. Therefore, the total net organic production of the whole reef system is probably almost zero and the whole reef system also acts as a source for atmospheric CO₂. Net calcification rates of the reef slope corals were much lower than those of the branching corals. The accumulation rate of the former was approximately 0.5 m kyr⁻¹ and of the latter was ~0.7–5 m kyr⁻¹. Consequently, reef slope corals could not grow fast enough to keep up with or catch up to rising sea levels during the Holocene. On the other hand, the branching corals grow fast enough to keep up with this rising sea level. Therefore, a transition between early Holocene and present-day reef communities is expected. Branching coral communities would have dominated while reef growth kept pace with sea level rise, and the reef was constructed with a branching coral framework. Then, the outside of this framework was covered and built up by reef slope corals and present-day reefs were constructed.     

Preliminary report on the biological effects of space flight on the producing strain of a new immunosuppressant, Kanglemycin C

Kanglemycin C (K-C) is a new immunosuppressant isolated from the culture broth of Nocardia mediterranei var. kanglensis 1747-64. To improve the productivity of K-C and to study the biological effects of space flight on its producing strain, spores from five K-C producing strains (U-10, U-15, U-7, M-13, γ-33) mutated from the wild strain N. mediterranei var. kanglensis 1747-64 were carried into space by an unmanned spaceship, “Shenzhou III” (Divine Vessel III) on March 25, 2002. Comparatively, the strain U-7 was the highest K-C producing strain among the above five starting strains when cultivated in 500-ml Erlenmeyer flasks. After a 6 day and 18 h flight, the treated spores went through serial screening processes to screen for high-yield K-C mutant strains, using thin layer chromatography and high performance liquid chromatography (HPLC). The K-C yield produced by one mutant strain, designated as F-16, derived from the starting strain U-7 was increased by up to 200% when compared to that produced by the starting strain U-7 in 500-ml Erlenmeyer flasks after careful postflight HPLC analysis. Another mutant strain, designated as F-210, derived from the starting strain M-13 showed reduced productivity of K-C as well as exhibited changes in some morphological and physiological characteristics. For example, the broth color of the strain F-210 changed from yellow to purple after 96 h of culture, but that of the ground control strain M-13 remained yellow. Similarly, the mycelium morphological change from filamentous to coccoid of F-210 occurred later than that of ground control M-13. Examination of the survivability of postflight spores indicated that exposure to radiation, during the 162 h of space flight, plays a critical role in the survival rates of spores such that spores exposed to strong radiation exhibited lower survival rates than spores exposed to weak radiation.Jianqin Zhou and Chenghang Sun have contributed equally to this work.     

The effect of a liquid seaweed extract from Ascophyllum nodosum (Fucales,Phaeophyta) on the two-spotted red spider mite Tetranychus urticae

This paper presents evidence from an initial trial in favor of claims that the liquid seaweed extract of Ascophyllum nodosum, marketed in the UK as Maxicrop, can reduce numbers of the two-spotted red spider mite Tetranychus urticae on crop plants. Seven applications of Maxicrop Triple over 20 days significantly suppressed the population build-up of two-spotted red spider mites on treated strawberry plants (Fragaria sp. var. Redgauntlet) raised under high polythene tunnels as compared to untreated controls.     

Delayed light studies on photosynthetic energy conversion. VII. Effect of the high energy state, coupled to 2,3,5,6-tetramethyl p-phenylenediamine-catalyzed cyclic electron flow, on millisecond emission from chloroplasts and digitonin subchloroplast particles

The effect of 2,3,5,6-tetramethyl p-phenylenediamine-catalyzed cyclic electron flow on millisecond delayed light emission from chloroplasts has been compared to the effect on subchloroplast particles. Non-cyclic electron flow of both chloroplasts and subchloroplast particles was blocked with 3-(3,4-dichlorophenyl)-1,1-dimethylurea. 2,3,5,6-tetramethyl p-phenylenediamine-catalyzed cyclic electron flow increased the millisecond delayed emission by 2–4 times in both chloroplasts and subchloroplast particles. Uncoupling conditions which collapse only the pH gradient component of the proton motive force reduced the 2,3,5,6-tetramethyl p-phenylenediamine stimulation of delayed light in chloroplasts but not in particles. The 2,3,5,6-tetramethyl p-phenylenediamine stimulation of delayed light in particles was sensitive to uncoupling conditions which are presumed to destroy the transmembrane potential. Energy transfer inhibitors were without effect on the 2,3,5,6-tetramethyl p-phenylenediamine stimulation in both chloroplasts and particles.

The 2,3,5,6-tetramethyl p-phenylenediamine stimulation of millisecond delayed emission appears to reflect the particular form of the proton motive force; in chloroplasts it seems to be correlated with the proton concentration gradient, whereas in particles it is more closely correlated with the transmembrane potential.