North Sea cod and climate change – modelling the effects of temperature on population dynamics

In order to examine the likely impacts of climate change on fish stocks, it is necessary to couple the output from large‐scale climate models to fisheries population simulations. Using projections of future North Sea surface temperatures for the period 2000–2050 from the Hadley General Circulation Model, we estimate the likely effects of climate change on the North Sea cod population. Output from the model suggests that increasing temperatures will lead to an increased rate of decline in the North Sea cod population compared with simulations that ignore environmental change. Although the simulation developed here is relatively simplistic, we demonstrate that inclusion of environmental factors in population models can markedly alter one's perception of how the population will behave. The development of simulations incorporating environment effects will become increasingly important as the impacts of climate change on the marine ecosystem become more pronounced.     

Absorption and imagery locate immune responses in the body

Imagery instructions specifying mucosal immunity should alter mucosal immunoglobulin A (m-IgA) levels in high absorbers, whose intent concentration evokes intense physiological responses. After screening for health status, 121 high or low absorbers were randomly assigned to either Relaxation Alone (R), Relaxation with Mucosal Immune Imagery (RI), or Vigilance Task control (VT). Before and after one 60-min intervention, subjects reported theory-relevant psychological variables and provided 5ml whole saliva, which was immediately frozen and assayed lateren masse with enzyme-linked immunoabsorbence (ELISA). MANOVA analysis of psychological variables replicated past research. ANOVA on residualized m-IgA found Time × Absorption interaction and Condition main effects. High more than low absorbers responded to relaxation with mucosal immune imagery by producing higher m-IgA. High absorbers appear able to locate where their immune systems will respond. Individual differences like absorption level need to be emphasized in diagnosis and treatment responsiveness.National Institutes of HealthM. Banks (Jasnoski) Gregerson, Department of Psychology, The George Washington University, changed to The Family Therapy Institute; Ingram M. Roberts, The George Washington University Medical Center, changed to Department of Medicine, Bridgeport Hospital; and Michael M. Amiri, The George Washington University Medical Center, changed to the Department of Neuroscience, NINDS Branch, National Institutes of Health. This research supported by an intra-mural BioMedical Research Grant from The George Washington University, was presented at the 1992 Annual Meeting of the Eastern Psychological Association, Boston, Massachusetts. Special thanks are extended to the following students who assisted instrumentally at various stages: undergraduates Lina Alathari, S. Theodor King, Beth Lieberman, Parisa Lotfi, Anita McClenon, and Karen Siscoe, and graduate student Mariken Hasert.     

The adaptive significance of colour pattern polymorphism in the Australian scincid lizard Lampropholis delicata

Females of Lampropholis delicata are dimorphic for colour pattern, the difference between morphs being the presence or absence of a distinct white mid-lateral stripe. A less distinct striped morph occurs also in males. We evaluated alternative hypotheses for the maintenance of this polymorphism by examining temporal and spatial variation in morph frequency, testing for differential selection among morphs using data on body size and reproductive traits from preserved specimens, and experimentally manipulating colour pattern in free-ranging lizards of both sexes, to assess the influence of the lateral stripe on survival rates. We found that the relative frequency of striped individuals varied among populations and decreased from north to south in both sexes, coincident with an increasing incidence of regenerated tails. Morph frequencies did not change through time within a population. Striped gravid females appeared to survive better and produced larger clutches than did non-striped females. In our experimental study, the relationship between survival and colour morph differed between the two sexes; males painted with a white lateral stripe had lower survival than control (brown stripe) males, but survival did not differ between striped and control females. The different response in the two sexes may be due partly to differences in temperature and microhabitat selection. We propose that the white lateral stripe decreases susceptibility to predators in gravid females but increases risk of predation in males, especially in combination with low temperatures. The polymorphism might be maintained by: (1) opposing fitness consequences of the stripe in males and females; (2) sex-specific habitat selection; and (3) gene flow in combination with spatial variation in relative fitness of the two morphs.     

Lack of metabolic temperature compensation in the intertidal gastropods,Littorina saxatilis (Olivi) and L. obtusata (L.)

Two intertidal snails, Littorina saxatilis (Olivi, 1972) (upper eulittoral fringe/maritime zone) and Littorina obtusata (Linnaeus, 1758) (lower eulittoral) were collected from a boulder shore on Nobska Point, Cape Cod, Massachusetts, in July and acclimated for 15–20 days at 4 ° or 21 °C. Oxygen consumption rate (Vo₂) was determined for 11–15 subsamples of individuals at 4 °, 11 ° and 21 °C with silver/platinum oxygen electrodes. Multiple factor analysis of variance (MFANOVA) of lo₁₀ transformed values of whole animal Vo₂ with log₁₀ dry tissue weight (DTW) as a covariant revealed that increased test temperature induced a significant increase in Vo₂ in both species (P<0.00001). In contrast, MFANOVA revealed that temperature acclimation did not affect Vo₂ in either L. saxatilis (P= 0.35) or L. obtusata (P= 0.095). Thus, neither species displayed a capacity for the typical metabolic temperature compensation marked by an increase in Vo₂ at any one test temperature in individuals acclimated to a lower temperature that is characteristic of most ectothermic animals. Lack of capacity for metabolic temperature acclimation has also been reported in other littorinid snail species, and may be characteristic of the group as a whole. Lack of capacity for respiratory temperature acclimation in these two species and other littorinids may reflect the extensive semi-diurnal temperature variation that they are exposed to in their eulittoral and eulittoral fringe/maritime zone habitats. In these habitats, any metabolic benefits derived from longer-term temperature compensation of metabolic rates are negated by extreme daily temperature fluctuations. Instead, littorinid species appear to have evolved mechanisms for immediate metabolic regulation which, in L. saxatilis and L. obtusata and other littorinids, appear to centre on a unique ability for near instantaneous suppression of metabolic rate and entrance into short-term metabolic diapause at temperatures above 20–35 °C, making typical seasonal respiratory compensation mechanisms characteristic of most ectotherms of little adaptive value to littorinid species.     

Assessment of protein solution versus crystal structure determination using spin- diffusion-suppressed NOE and heteronuclear relaxation data

A spin-diffusion-suppressed NOE buildup series has been measured for E. coli thioredoxin.The extensive 13C and 15N relaxation data previously reported for this protein allow fordirect interpretation of dynamical contributions to the 1H-1H cross-relaxation rates for a largeproportion of the NOE cross peaks. Estimates of the average accuracy for these derived NOEdistances are bounded by 4% and 10%, based on a comparison to the corresponding X-raydistances. An independent fluctuation model is proposed for prediction of the dynamicalcorrections to 1H-1H cross-relaxation rates, based solely on experimental structural andheteronuclear relaxation data. This analysis is aided by the demonstration that heteronuclearorder parameters greater than 0.6 depend only on the variance of the H-X bond orientation,independent of the motional model in either one- or two-dimensional diffusion (i.e., 1– S2 = 3/4 sin2 2 ). The combination of spin-diffusion-suppressed NOEdata and analysis of dynamical corrections to 1H-1H cross-relaxation rates based onheteronuclear relaxation data has allowed for a detailed interpretation of various discrepanciesbetween the reported solution and crystal structures.     

低温预处理过程中大麦花药内源激素的变化

很多文章曾报道低温预处理可以明显提高大麦花药反应频率。但对于低温预处理的机理,至今研究报道甚少。我们应用ＥＬＩＳＡ方法测定了大麦花药低温预处理过程中内源激素ＩＡＡ、ｉＰＡ和ＡＢＡ含量。根据实验结果,推测低温预处理改变了花药内源ＩＡＡ和ｉＰＡ含量,阻断了花粉原来的发育方向,使其由配子体的发育途径转向孢子体的发育途径。     

Fluctuation of body temperature and cuckoo brood parasitism

Body temperatures of 11 bird species, including cuckoos, were measured in an artificial meteorological room. Ratios of change in body temperature to that in air temperature were thereby obtained for each species. Cuckoos demonstrate a remarkably high value, indicating a particularly low ability to regulate body temperature. Viewed in this light, the cuckoo's parasitic behavior is very likely an adaptation to overcome a physiological disadvantage. This in turn might be expected to reinforce delay in evolution of temperature homeostasis.