Effects of 12 weeks of aerobic exercise plus dietary restriction on body composition, resting energy expenditure and aerobic fitness in mildly obese middle-aged women

This study investigated the effects of 12 weeks of aerobic exercise plus voluntary food restriction on the body composition, resting metabolic rate (RMR) and aerobic fitness of mildly obese middle-aged women. The subjects were randomly assigned to exercise/diet (n = 17) or control (n = 15) groups. The exercise/diet group participated in an aerobic training programme, 45–60 min · day ^–1 at 50%–60% of maximal oxygen uptake (VO_2max), 3–4 days · week^–1, and also adopted a self-regulated energy deficit relative to predicted energy requirements (–1.05 MJ · day ^–1 to –1.14 MJ · day ^–1 ). After the regimen had been followed for 12 weeks, the body mass of the subjects had decreased by an average of 4.5 kg, due mainly to fat loss, with little change of fat free mass (m _ff). The absolute RMR did not change, but the experimental group showed significant increases in the RMR per unit of body mass (10%) and the RMR per unit of m _ff (4%). The increase in RMR/m _ff was not correlated with any increase in VO_2max/m _ff. The resting heat production per unit of essential body mass increased by an average of 21%, but the resting heat production rate per unit of fat tissue mass remained unchanged. We concluded that aerobic exercise enhances the effect of moderate dietary restriction by augmenting the metabolic activity of lean tissue.     

Species composition of dabbling duck assemblages: ecomorphological patterns compared with null models

Ecomorphological patterns of breeding dabbling duck (Anas spp.) assemblages were studied in six regions in northern Europe. Observed spacings among species in terms of bill lamellar density and body length were compared with expected spacings based on null models incorporating different levels of constraints (regional species pools, species relative abundances, lake size and habitat requirements of species). Deviations of observed spacings from expected ones were compared with prey abundance and prey size diversity in the lakes. Observed spacings in terms of body length, but not in terms of bill lamellar density, were greater than expected on the basis of null models. The most abundant species were generally relatively more different than less abundant species in terms of body length but not in terms of bill lamellar density. Deviations between observed and expected spacings in terms of body length were more like those predicted by the competition hypothesis in lakes with low food abundance than in lakes with high food abundance. Patterns in bill lamellar spacings were not related to food abundance nor to food size diversity. In general, patterns in body length spacings were consistent with the competition hypothesis whether the null model used in comparisons was constrained or not.     

The effects of tail autotomy on survivorship and body growth of Uta stansburiana under conditions of high mortality

We examined the effects of tail autotomy on survivorship and body growth of both adult and juvenile Uta stansburiana by directly manipulating tail condition. Tail loss decreased neither survivorship nor rate of body growth for individuals in two natural populations. Lack of an influence of tail loss on survivorship in these two populations may be the result of high mortality. Under high mortality any differential effects of tail loss will be lower than in populations facing lower mortality. Growth experiments in the laboratory demonstrated that, under conditions of minimal environmental variation and social interactions, there is no tradeoff between body growth and tail regeneration as has been suggested for other species of lizards. One possible reason for this difference is that U. stansburiana does not use the tail as a storage organ for lipids. The original and regenerated tails are composed mainly of protein. In general, any differential body growth between tailed and tailless individuals may be due to social interactions and not a diversion of limited energy into tail regeneration.     

On the relationship between food, reproduction and survival of two carabid beetles: Calathus melanocephalus and Pterostichus versicolor

Abstract.

• 1 The relative influences of temperature and availability of food on reproduction, survival and growth of all developmental stages of two carabid beetle species are discussed with special reference to the suggested relationship between availability of food, size of egg production and survival of adults from one breeding season to the next.
• 2 Temperature as well as food supply influence the length of larval growth and adult body size. Beetles grown at low temperatures and low amounts of food are smaller than those grown at higher temperature and with more food.
• 3 The number of eggs laid per female was correlated with the amount of food gathered. There was no inverse relationship (trade-off) between reproductive output and survival in the field until the next breeding season.
• 4 In 1980 no significant relationship was found between winter mortality and the amounts of food gathered by beetles in the period after reproduction and before winter diapause. However, in 1981 in C. melanocephalus a lower number of starved beetles survived the winter than the fed ones and‘field’beetles.
• 5 Only in the first part of the feeding activity period in autumn can enough food be gathered by C.melunocephalus for successful hibernation. In the second part of this period there is not enough food to build up the fat reserves needed to survive the winter.
• 6 Difference in population fluctuations of both species are discussed in relation to their life histories.

     

Kinetics and stereochemistry of the microsomal epoxide hydrolase-catalyzed hydrolysis of cis-stilbene oxides

The microsomal epoxide hydrolase (mEH)-catalyzed hydrolysis of cis-4,4′–dimethylstilbene oxide ( 1a ), cis-4,4′-diethylstilbene oxide ( 1b ), cis-4,4′-diisopropylstilbene oxide ( 1c ), and cis-4,4′-dichlorostilbene oxide ( 1d ) have been investigated using rabbit liver microsomal preparations. The kinetic parameters, K_m and V_max, and the absolute stereochemistry of the reactions have been determined and compared with those of cis-stilbene oxide ( 1e ). All epoxides 1a – d are hydrolyzed by mEH with high product enantioselectivity to give (R,R)-(+)-diols with ee ≥ 90%. The presence of the substituents on the phenyl rings markedly reduces the rates of mEH catalyzed hydrolysis with respect to cis-stilbene oxide, by increasing K_m and reducing V_max in the cases of 1a , 1b , and 1d , or reducing only the V_max in the case of 1c . The very low V_max, together with a persistent ability to fit into the mEH active site, make all these epoxides, and particularly 1c , inhibitors of cis-stilbene oxide hydrolysis. The kinetic and stereochemical results are interpreted on the basis of the proposed topology of the mEH active site. © 1994 Wiley-Liss, Inc.     

植被生态信息的典范相关分析技术理论

植被生态信息分析中对两（多）组取样集间的相关分析的需求导致了典范相关分析技术的应用和发展。本文对典范相关分析技术的原理、典范参数的生态学意义进行了提示,比较了典范相关分析与ＰＣＡ之间的差异,产在典范相关分析技术的应用过程中,原始数据的预处理提出了建议。     

Size structure of the metazoan community in a Piedmont stream

We characterized the size structure of virtually the entire metazoan community in a fourth order, sandybottomed Piedmont stream during late summer. Our study, the first to sample across all habitat types and sizes of metazoans in an aquatic ecosystem, indicates that at the community level, stream size spectra may be bimodal for the benthos or trimodal when fish are included. Animals spanning 10 orders of magnitude in dry mass (from gastrotrichs to fish) were quantitatively collected from nine habitat types. The bimodal benthic size spectrum was characterized by a meiofaunal component (mostly oligochaetes and micro-crustacea) and a macrobenthic component (mostly the introduced asiatic clam, Corbicula fluminea). Insects contributed little to overall standing crop. Size-specific contribution to whole-community metabolism was assessed using allometric equations for respiration, and we found a distinctly bimodal distribution across the entire metazoan size range, with peaks in the meiofaunal and benthic macrofaunal size ranges. Our bimodal benthic size spectrum is similar to that observed for marine benthos but not to other freshwater benthic systems, possibly because the entire range of habitat types and/or animal sizes were not sampled in the latter. Numerous factors may influence size spectra in stream ecosystems, including local geomorphic (habitat) conditions, water level fluctuations, species introductions, and predation processes.     

Changes in water relation parameters under osmotic and salt stresses in maize and sorghum

A relatively drought tolerant cultivar of maize ( Zea mays L. cv. Pioneer 3950) and a drought tolerant line of sorghum ( Sorghum bicolor [L.] Moench cv. ICSV 112) were grown hydroponically for 11 days. Treatments for non-ionic osmotic and salt stresses were started at the 8th day by addition of polyethylene glycol 6000 and NaCl, respectively, at 200 mOsm equivalent concentrations in the presence or absence of 0. 1 μ M abscisic acid. Relative growth rate was depressed by both stress factors, more severely for maize than sorghum. Abscisic acid increased the growth rate and reverted the negative effect of NaCl in maize, while sorghum was only slightly affected. In general, sorghum had higher levels of K⁺ and lower levels of Na⁺ and the K⁺/Na⁺ ratio was further increased by abscisic acid treatment. From the pressure-volume curves, osmotic potential, the water potential at turgor loss point, bulk elastic modulus and the water saturation deficit at initial turgor loss were estimated. Most significantly, sorghum had a higher elastic modulus than maize and it decreased under osmotic treatment, while in maize it increased under NaCl stress. The results suggest that bulk tissue turgor was not limiting growth under these conditions and underscores the possible implications of changes in the elastic condition of the cell walls in stress responses.     

温度对麦长管蚜种群存活率的特征参数的影响

在测定麦长管蚜种群存活率基础上,本提出反S型曲线模型来描述种群存活率,探讨了麦长管蚜种群存活率过程变化的特征参数,并得到不同的特征值．