Evolutionary implications of the human aldolase-A, -B, -C, and -pseudogene chromosome locations.

The aldolase genes represent an ancient gene family with tissue-specific isozymic forms expressed only in vertebrates. The chromosomal locations of the aldolase genes provide insight into their tissue-specific and developmentally regulated expression and evolution. DNA probes for the human aldolase-A and -C genes and for an aldolase pseudogene were used to quantify and map the aldolase loci in the haploid human genome. Genomic hybridization of restriction fragments determined that all the aldolase genes exist in single copy in the haploid human genome. Spot-blot analysis of sorted chromosomes mapped human aldolase A to chromosome 16, aldolase C to chromosome 17, the pseudogene to chromosome 10; it previously had mapped the aldolase-B gene to chromosome 9. All loci are unlinked and located on to two pairs of morphologically similar chromosomes, a situation consistent with tetraploidization during isozymic and vertebrate evolution. Sequence comparisons of expressed and flanking regions support this conclusion. These locations on similar chromosome pairs correctly predicted that the aldolase pseudogene arose when sequences from the aldolase-A gene were inserted into the homologous aldolase location on chromosome 10.     

Sex determination from the radius in humans

The discriminatory capacity of the radius in sex determination was investigated in a Dutch skeletal collection of recent origin. Midshaft subperiosteal diameter, maximum length and maximum transverse distal width were measured from roentgenograms. The discriminatory capacity of the radius was found to be of the same order as that reported in the literature for the other long bones. Maximum transverse distal width showed the highest consistency (85%) between estimated and documented sex. This method requires only the presence of the distal fragment of the radius.     

Scaling analysis of coral reef systems: an approach to problems of scale

Dimensional analysis and scaling are related, semi-formal procedures for capturing the essential process(es) controlling the behaviour of a complex system, and for describing the functional relationships between them. The techniques involve the parameterization of natural processes, the identification of the temporal and spatial scales of variation of processes, and the evaluation of potential interactions between processes referenced to those scales using non-dimensional (scaled) parameters. Scaling approaches are increasingly being applied to a broad range of marine ecological problems, with the aims of assessing the relative importance of physical and biological parameters in controlling variation in process rates, and placing limits on the ability of one process to affect another. The value of the approach to coral reef research lies in the conceptualization of relationships between discipline-specific processes, and the evaluation of scale-dependent processes across the large range of spatial and temporal scales which pertain to coral reefs. Characteristic scales of physical, geological and biological processes exhibit different patterns of distribution along the temporal dimension. Scaling arguments based on examples from reef systems indicate that a large group of biological and biogeochemical processes are strongly influenced by hydrodynamic processe occuring at similar time scales within the range from about on hour to one year. We argue that scaling approaches to process-related problems are pre-requisite to interdisciplinary research on coral reefs.     

The majority of cellular fatty acid acylated proteins are localized to the cytoplasmic surface of the plasma membrane

The BC3Hl muscle cell line was previously reported to contain a broad array of fatty acid acylated proteins [Olson, E. N., Towler, D. A., & Glaser, L. (1985) J. Biol. Chem. 260, 3784-3790]. Palmitate was shown to be attached to membrane proteins posttranslationally through thiol ester linkages, whereas myristate was attached cotranslationally, or within seconds thereafter, to soluble and membrane-bound proteins through amide linkages [Olson, E. N., & Spizz, G. (1986) J. Biol. Chem. 261, 2458-2466]. The temporal and subcellular differences between palmitate and myristate acylation suggested that these two classes of acyl proteins might follow different intracellular pathways to distinct subcellular membrane systems or organelles. In this study, we examined the subcellular localization of the major fatty acylated proteins in BC3Hl cells. Palmitate-containing proteins were localized to the plasma membrane, but only a subset of myristate-containing proteins was localized to this membrane fraction. The majority of acyl proteins were nonglycosylated and resistant to digestion with extracellular proteases, suggesting that they were not exposed to the external surface of the plasma membrane. Many proteins were, however, digested during incubation of isolated membranes with proteases, which indicates that these proteins face the cytoplasm. Two-dimensional gel electrophoresis of proteins labeled with [3H]palmitate and [3H]myristate revealed that individual proteins were modified by only one of the two fatty acids and did not undergo both N-linked myristylation and ester-linked palmitylation. Together, these results suggest that the majority of cellular acyl proteins are routed to the cytoplasmic surface of the plasma membrane, and they raise the possibility that fatty acid acylation may play a role in intracellular sorting of nontransmembranous, nonglycosylated membrane proteins.     

Euthanasia and the active-passive distinction

The author examines various claimed differences between active and passive euthanasia and, if there are differences, whether they are morally significant. He refutes arguments based on acting vs. not acting, intention, double effect, cause of death, and natural law theory. Reichenbach proposes that the most helpful distinction is the one between intentional killing (active euthanasia) and appropriate treatment for the dying or terminally ill (passive euthanasia). Significant moral difference, however, rests on the contention that intentional killing is always wrong and that, all else being equal, dying by natural means is intrinsically good, whereas dying by unnatural means is not.     

Stonefly nymphs use hydrodynamic cues to discriminate between prey

Summary Playback experiments conducted in a Rocky Mountain, USA, stream determined whether predatory stonefly nymphs (Kogotus modestus; Plecoptera: PerlodiMae) used hydrodynamic cues to discriminate prey species from nonprey species. In the laboratory we recorded pressure wave patterns associated with swimming escape behavior of Baetis bicaudatus (Baetidae), the favored mayfly prey species, and those of a nonprey mayfly, Ephemerella infrequens (Ephemerellidae). We video taped the responses of 24-h starved Kogotus to Baetis playbacks, Ephemerella playbacks or no playbacks made by oscillating (or not) live mayflies (Ephemerella) or clear plastic models placed within in situ flow-through observation boxes. The probability of attacks per encounter with Baetis playbacks was highest and independent of the model type used, but Kogotus also showed an unexpected high probability of attacks per encounter when Ephemerella playbacks were made through live Ephemerella. Thus, Kogotus discriminated between Baetis and Ephemerella swimming patterns but only when playbacks were made through the plastic model. Kogotus never attacked motionless mayflies or motionless plastic models. We allowed some Kogotus to successfully capture one small Baetis immediately before playbacks, which resulted in a much higher probability of attacks per encounter with Baetis playbacks on either model and a heightened discrimination of prey versus nonprey playbacks. The probability of attacks per encounter by Kogotus with live Baetis swimming under similar experimental conditions was strikingly similar to its response to Baetis playbacks made by oscillating the plastic model after a successful capture. Order of playback presentation (Baetis first or Ephemerella first) did not influence predatory responses to mayfly swimming patterns. This study is the first to document the use of hydrodynamic cues by stream-dwelling predators for discrimination of prey from nonprey and provides a mechanism to explain selective predation by stoneflies on Baetis in nature.     

The effect of sucrose on the levels of abscisic acid, indoleacetic acid and zeatin/zeatin riboside in wheat ears growing in liquid culture

The influence of a varied sucrose supply on grain size and hormonal contents of detached wheat ears ( Triticwn aestivum L. cv. Schirokko) was investigated throughout grain development. In ears led limited amounts, or no sucrose, grain weights in both proximal and distal grain positions of the ear were reduced. Radioimmunoassay for abscisic acid, indoleacetic acid and zeatin/zeatin riboside showed that the changes in the levels of these hormones in grains and bracts were comparable to intact ears when detached ears were well supplied with sucrose. Under conditions of limited sucrose supply, higher abscisic acid levels in the distal and proximal grains of detached ears were found compared to ears supplied with adequate sucrose. Limiting sucrose supply to the ear did not alter the levels of indoleacetic acid or zeatin/zeatin riboside in either the grains or bracts of detached ears.     

Humoral factors released during trauma ofAplysia body wall

1. Preliminary, general chemical characteristics of substances in artificial sea water (ASW) washed through stimulated body wall (SBW) and in hemolymph taken from noxiously stimulated animals (SHL) were consistent with those of classical neurotransmitters, amino acids, and small- to medium-sized peptides. 2. 5-Hydroxytryptamine (5HT) and acetylcholine (ACh), unlike SBW and SHL, caused relaxation when perfused into isolated body wall. FMRFamide produced a biphasic response--brief contraction followed by prolonged relaxation. 3. Small cardioactive peptide (SCPB) caused body wall contractions similar to those produced by SBW and SHL, except that SCPB contractions displayed more desensitization and were completely blocked by 30 mM CoCl2. SCPB and SBW contractions were synergistic. 4. Dopamine caused persistent body wall contractions similar to those of SBW and SHL. Dopamine contractions were reduced but not blocked by 30 mM CoCl2. Unlike SBW activity, dopamine activity was reduced by alkalinization. 5. Glutamate and taurine produced strong but usually short-lasting body wall contractions. Adenosine, octopamine, arginine vasotocin, and cholecystokinin (CCK-8) caused weak or variable contractions. Met-enkephalin and somatostatin caused no obvious body wall responses. 6. When superfused over the fully sheathed abdominal ganglion, FMRFamide, met-enkephalin, glutamate, aspartate, and taurine reduced the magnitude of the gill-withdrawal reflex elicited by siphon nerve stimulation. 7. Taken together with earlier results, these data suggest a preliminary framework for trauma signal pathways. It is proposed that stress hormones (perhaps including FMRFamide, SCPs, 5HT, and dopamine) are released into hemolymph from neuroendocrine cells. Effective amounts of active intracellular solutes such as amino acids may also be released by extensive cellular rupture. Various humoral signals produce slow effects that contribute to hemostasis, balling up, increased cardiac output, and reflex suppression.     

Insulin binding in the hypothalamus of lean and genetically obese Zucker rats

Recent reports have suggested that the obesity and hyperphagia of the genetically obese Zucker rat may be related to defective insulin action or binding in the hypothalamus. We used quantitative autoradiography to determine if insulin binding is altered in specific hypothalamic nuclei associated with food intake. Insulin binding was measured in the arcuate (ARC), dorsomedial (DMN), and ventromedial (VMN) hypothalamic nuclei of 3–4-month-old lean (Fa/Fa) and genetically obese (fa/fa) Zucker rats. A consistently reproducible 15% increase in the total specific binding of 0.1 nM [¹²⁵I]-insulin was found in the ARC of the obese genotype. A slight increase in insulin binding in the DMN was also found. No difference in specific insulin binding was found between genotypes in the VMN. Nonlinear least squares analysis of competitive binding studies showed that the K_d of the ARC insulin binding site was 33% higher in the lean rats than in the obese rats, indicating an increased affinity for insulin. No difference in site number (B_max) was found in the ARC, DMN or VMN, and no evidence was found for reduced insulin binding in the hypothalamus of the obese (fa/fa) genotype. The results suggest that hyperphagia and obesity of the obese (fa/fa) Zucker rat genotype may be associated with increased insulin binding in the arcuate nucleus.     

Differential expression of guinea pig class II major histocompatibility complex antigens on vascular endothelial cells in vitro and in experimental allergic encephalomyelitis

Previous studies have shown that vascular endothelial cells do not normally express major histocompatibility complex (MHC) Class II antigens either in vivo or in vitro. In this investigation it was found that endothelial in the central nervous system (CNS) of normal guinea pigs constitutively express MHC Class II antigens recognized by the monoclonal antibodies HLA-DR, 27E7, and MSgp8. This phenotype is retained when these CNS-derived endothelial cells are propagated in tissue culture. Furthermore, examination of CNS tissue taken from animals in the acute phase of chronic relapsing experimental allergic encephalomyelitis shows that additional epitopes of the MHC Class II antigen, detected by the monoclonal antibodies CI.13.1 and 22C4, are present during the diseased state. This study not only demonstrates constitutive expression of certain MHC Class II determinants by guinea pig endothelial cells, but also shows that other Class II determinants can be differentially expressed in certain disease states.