DNA divergence in and around the alcohol dehydrogenase locus in five closely related species of Hawaiian Drosophila

The alcohol dehydrogenase (Adh) region from five planitibia subgroup species of Hawaiian picture-wing Drosophila has been cloned. A total of 15 kb of DNA in and around the Adh gene has been compared among the five species. Genetic distances were calculated to determine evolutionary relationships. These distances agree with previous distances determined by protein polymorphism and DNA hybridization techniques and can be interpreted in terms of specific island colonization and speciation (founder) events over the past 5 Myr. Examination of the restriction maps of the cloned Adh region from the five species shows many instances of small deletions, insertion of a transposable element in D. heteroneura, and the existence of a highly variable region on the 3' side of the Adh gene. Clustering relationships and rates of DNA change are calculated and compared with the relationship found for other species of Drosophila.      

Different effects of pentobarbital on two gamma-aminobutyrate receptors from rat brain: channel opening, desensitization, and an additional conformational change

The effect of pentobarbital on the responses of the gamma-aminobutyric acid (GABA) receptor from rat brain was studied in quantitative measurements of GABA-mediated chloride-exchange rates (reflecting channel-opening equilibrium) and receptor desensitization rates by using 36Cl- tracer ion with native membrane vesicles. Pentobarbital effected the two phases of 36Cl- influx in different ways, supporting previous evidence that these are mediated by two different receptors [Cash, D. J., & Subbarao, K. (1987) Biochemistry 26, 7556; Cash, D. J., & Subbarao, K. (1987) Biochemistry 26, 7562]. Both the chloride-exchange rate and the desensitization rate of the faster desensitizing receptor were increased by pentobarbital at concentrations above 20 microM by an allosteric effect shifting the response curve to lower GABA concentrations. A similar enhancement of the responses of the slower desensitizing receptor occurred up to 200 microM pentobarbital. Two pentobarbital effector sites were involved in the allosteric mechanism. Above 500 microM pentobarbital, both the initial chloride-exchange rate and the desensitization rate of the slower desensitizing receptor were decreased. This inhibition, which was immediate, occurred with saturating as well as low GABA concentrations and therefore was not attributed to decreased GABA binding but to inhibitory sites for pentobarbital, different from the allosteric activating sites and the GABA binding sites. The chloride ion exchange activity was seen to recover with time, at concentrations above 1000 microM pentobarbital, in a process with a very steep dependence on pentobarbital concentration. This reactivation was attributed to the conversion of an initial form of the receptor to a final form that was less inhibited by pentobarbital. The similarity of the effects of pentobarbital on the chloride ion exchange with its effects on electrophysiological measurements supports the fact that these different techniques study the same phenomena. Comparisons of the effects of pentobarbital on desensitization and on high-affinity ligand binding measurements suggest that increased GABA binding at equilibrium reflects an increased conversion to the desensitized state.     

A quantitative analysis of the development of the central nervous system in juvenile Aplysia californica

The marine mollusc Aplysia californica has proved to be a useful preparation for analyzing the development of learning and memory on both behavioral and cellular levels. An important issue in this analysis concerns the anatomical substrate upon which learning is superimposed during development. As a first step in examining this question, in the present study we have determined the number of neurons in all the major central ganglia at each stage during juvenile development, a time when several forms of learning first emerge in Aplysia. We found that a large and highly nonlinear proliferation of neurons occurs during juvenile development, with the greatest increase in cell number occurring during a specific juvenile stage: Stage 12. The neuronal proliferation is system-wide, occurring in each of the central ganglia simultaneously, suggesting the action of a general developmental signal or trigger (perhaps a hormone). Accompanying the increase in neuron number in Stage 12 there is a large increase in neuropilar volume (150-fold), which significantly increases the opportunity for synaptic interactions late in juvenile development.     

Prejudice Toward Fat People: The Development and Validation of the Antifat Attitudes Test

LEWIS, ROBIN J, THOMAS F CASH, LORA JACOBI, CRISTINA BUBB-LEWIS. Prejudice toward fat people: The development and validation of the Antifat Attitudes Test. Although the stigma of obesity in our society in well documented, the measurement of antifat attitudes has been a difficult undertaking. Two studies were conducted to construct and validate the Antifat Attitudes Test (AFAT). In study 1, college students (110 men and 175 women) completed the preliminary 54-item AFAT and specific indices of body image and weight-related concerns. Psychometric and factor analysis revealed a 47-item composite scale and three internally consistent factors that were uncorrelated with social desirability: Social/Character Disparagement, Physical/Romantic Unattractiveness, and Weight Control/Blame. Several body image correlates of antifat prejudice were identified, and men expressed more negative attitudes than women. Study 2 experimentally examined the effects of information about the controllability of weight on the antifat attitudes of 120 participants. Exposure to information on behavioral vs. biogenetic control led to greater blame of persons who are fat for their body size. The implications of the findings and the potential utility of the AFAT are discussed.     

Serum Fibrin/Fibrinogen Degradation Products Associated with Postoperative Pulmonary Embolus and Venous Thrombosis

A total of 76 “high-risk” surgical patients were studied for evidence of venous thromboembolic disease. Episodes of deep vein thrombosis and of pulmonary embolism were related to changes in blood levels of fibrin degradation products (F.D.P.). When diagnosed either by ordinary clinical means or by venography and isotope scanning significantly raised F.D.P. levels were found in all cases. Serum F.D.P. estimations are unlikely to help in detecting deep vein thrombosis, but may prove valuable in diagnosing pulmonary embolism.     

Cholera Seasonality in Madras (1901–1940): Dual Role for Rainfall in Endemic and Epidemic Regions

The seasonality of cholera and its spatial variability remain unexplained. Uncovering the role of environmental drivers in these seasonal patterns is critical to understand temporal variability at longer time scales, including trends and interannual variability. Rainfall has been proposed as a key driver of the seasonality of cholera. To address this hypothesis, we examine the association between rainfall and cholera in both time and space using the extensive historical records for the districts of Madras in former British India (1901–1940). We show the existence of two main spatial clusters that differ not just in the effect of rainfall but also in the seasonal pattern and frequency of periods with and without cholera mortality. The results support a model of cholera seasonality with two different routes of transmission: one is enhanced by increasing rainfall (in areas with abundant water), the other is buffered by increasing water. We discuss how the dual nature of the influence of rainfall creates different temporal patterns in regions where cholera is either “endemic” or “epidemic.”