PCBs and other toxicants inMysis relicta

This research considers the role ofMysis relicta in the recycling of toxic organics in the Lake Michigan ecosystem. Mysids were collected at a station 20 km offshore of Grand Haven, Michigan in spring, summer, and autumn and then size-sorted. In October 1980 and May 1981, plankton samples were collected in two size categories: >78 µm and >156 µm. Mysid fecal pellets andPontoporeia hoyi were collected in May 1981 while a fourhorn sculpin (Myoxocephalus quadicornis) was collected in October 1980. Concentrated extracts of all samples were analyzed for chlorinated hydrocarbons using electron capture gas chromatography. Toxic organics detected were, in order of concentration: PCB, DDE, dieldrin, -chlordane, and HCB. DDT, DDD, and -chlordane were detected less frequently. PCB concentrations in mysids were similar to those observed in their plankton diet and there was no evidence of increased bioaccumulation with increased mysid age. Dieldrin and DDE generally occurred in higher concentrations in older than in younger mysids. Dieldrin concentrations were lower in the plankton than in mysids. Certain toxicants (PCBs, DDD, dieldrin, and -chlordane) occurred in higher concentrations inPontoporeia hoyi than in mysids. Concentrations in the sculpin generally were intermediate to those in amphipods and mysids. Our study suggests that mysids have a significant role in the recycling of toxic organics and that the characteristic pathways vary with the contaminant.     

Aminoacyl-tRNAs from Physarum polycephalum: patterns of codon recognition.

Isoacceptors of Physarum polycephalum Ala-, Arg-, Glu-, Gln-, Gly-, Ile-, Leu-, Lys-, Ser-, Thr-, and Val-tRNAs were resolved by reverse-phase chromatography and isolated, and their codon recognition properties were determined in a ribosomal binding assay. Codon assignments were made to most isoacceptors, and they are summarized along with those determined in other studies from Escherichia coli, yeasts, wheat germ, hymenoptera, Xenopus, and mammals. The patterns of codon recognition by isoacceptors from P. polycephalum are more similar to those of animals than to those of plants or lower fungi.     

An improved large-scale synthesis of PEG-peptides for gene delivery.

Polyethylene glycol (PEG)-peptides are under development as components of nonviral gene delivery systems. Several earlier reports have demonstrated that covalent attachment of PEG to the surface of peptide condensed DNA particles blocks non-specific biodistribution during gene targeting. In this study, we report an improved large-scale synthesis and purification of a DNA condensing PEG-peptide used for gene delivery. The new method takes advantage of low-pressure cation-exchange chromatography to isolate dimeric Cys-Trp-Lys(18). The dimeric peptide was reduced and directly conjugated with PEG-maleimide resulting in PEG-Cys-Trp-Lys(18). The PEG-peptide was purified by low-pressure chromatography affording 50 mumol (400 mg) quantities of PEG-peptide in >95% purity. The approach offers the advantage of avoiding preparative high-performance liquid chromatography (HPLC) purifications of polylysine peptides to increase yield and capacity.     

PERSPECTIVE: CHASE-AWAY SEXUAL SELECTION: ANTAGONISTIC SEDUCTION VERSUS RESISTANCE

A model of sexual selection that leads to the evolution of exaggerated male display characters that is based on antagonistic coevolution between the sexes is described. The model is motivated by three lines of research: intersexual conflict with respect to mating, sensory exploitation, and the evolution of female resistance, as opposed to preference, for male display traits. The model generates unique predictions that permit its operation to be distinguished from other established models of sexual selection. One striking prediction is that females will frequently win the coevolutionary arms race with males, leaving them encumbered with costly ornaments that have little value except that their absence understimulates females. Examples from the literature suggest that the model may have broad application in nature. The chase-away model is a special case of the more general phenomenon of Interlocus Contest Evolution (ICE).     

Commingling and segregation analysis of blood pressure in a French-Canadian population.

Using genetic linkage we have localized the gene coding for galactocerebrosidase (GALC) to human chromosome 14. Patients with Krabbe disease and their family members were assayed for GALC activity in leukocytes or fibroblasts and were classified as affected, carrier, noncarrier, or unknown. Polymorphic DNA markers from chromosome 14 demonstrated a multipoint LOD score of 3.40 with GALC located 13 cM centromere distal to CRI-C70 (D14S24). This finding is consistent with the location of the mouse twitcher mutation (a model of human GALC deficiency) on chromosome 12, which has substantial homology to human chromosome 14. Our data do not support a previous report's localization of GALC to chromosome 17.     

A genetic study of immunoglobulin E and atopic disease based on families ascertained through asthmatic children

In order to investigate the modes of inheritance of serum immunoglobulin E (IgE) levels and atopic disease, serum IgE levels and data on allergic disease were obtained from 42 families ascertained through asthmatic children visiting an allergy clinic. Although the mean IgE levels were elevated (mean 637 U/ml), the prevalence of atopic disease in this population was surprisingly low. When the data were analyzed using complex segregation analysis, no major locus could be detected. Moreover, the polygenic heritability was unexpectedly small even though the correlation between serum IgE levels and the liability to atopic disease was around 0.4. Given this unusual set of findings, it is postulated that parasitic infections in this population have (in accordance with well-established results of parasitic disease) caused both elevated levels of serum IgE and a decreased prevalence of allergic disease with the possible masking of the various genetic components of serum IgE levels and atopic disease.     

Relative abundance of human placental phospholipase A2 messenger RNA in late pregnancy.

The aim of this study was to determine messenger RNA (mRNA) levels for a specific phospholipase A2 (PLA2) in human placenta during late gestation prior to the onset of labour. The relative abundance of human placental mRNA for a nonpancreatic Group II PLA2 was determined using cDNA clone specific for this PLA2. Twenty seven placentae were collected from women undergoing elective (i.e. before the onset of labour) Caesarean section between 37 and 41 completed weeks gestation. The relative amount of human placental PLA2 mRNA did not change significantly over this period of late pregnancy (p greater than 0.8). Previously, we have demonstrated that placental PLA2 messenger RNA levels are increased in association with spontaneous onset labour at term in the human. The data obtained in this current study are consistent with the conclusion that the regulation of this human placental PLA2 gene is tightly controlled around the time of parturition and that its expression is increased acutely in association with labour.     

Comparison of N-glycosides of fetuins from different species and human alpha 2-HS-glycoprotein.

Complex type N-glycosides of commercial bovine fetuin preparations from pooled fetal calf serum have been shown to contain comparable amounts of Gal4,4,4TRI (see structure A below) and Gal4,4,3TRI (structure B) as major asialo-structures. To investigate whether there is a clear genetic specificity for synthesis of these oligosaccharides, N-glycosides from two preparations of bovine fetuin, each from a single calf, were examined. Both of these structures were present in each calf, and there was only a subtle quantitative difference in the ratio of these two structures between the calves. Thus, a specific galactosyltransferase, presumably required for the biosynthesis of the Gal4,4,3TRI structure, may exist in both of these individual calves. Comparison of fetuin N-glycosides was also extended to sheep, pig, and human alpha 2-HS-glycoprotein, the human counterpart of bovine fetuin, using high-pH anion-exchange chromatography of the reducing oligosaccharides as well as HPLC of their pyridinylamino derivatives. The N-glycosides of ovine fetuin also have both Gal4,4,4TRI and Gal4,4,3TRI structures in a ratio similar to that of bovine fetuin. However, the major N-glycoside of porcine fetuin is of a fucosyl biantennary complex type structure (structure C below) and human alpha 2-HS-glycoprotein has an N-glycoside which is almost exclusively a nonfucosylated biantennary structure (structure D). This species-specific presence of N-glycosides of fetuins and comparison with N-glycosides of other glycoproteins suggest that the polypeptide sequence of a glycoprotein may affect its N-glycan structure by regulating the activity of specific glycosyltransferases. [formula: see text]     

A study of the effect of the irreversible delta receptor antagonist [D-Ala2,Leu5,Cys6]-enkephalin on delta cx and delta ncx opioid binding sites in vitro and in vivo.

Several lines of data support the existence of two classes of delta receptors: the delta cx binding site, which is the delta binding site of the mu-delta opioid receptor complex, and the delta ncx, which is the noncomplexed delta receptor. [D-Ala2,Leu5,Cys6]Enkephalin (DALCE) is an extended analog of [Leu5]enkephalin, which has been shown to bind irreversibly to delta receptors via the terminal cysteine by formation of a disulfide bond with the receptor. In vivo studies have shown that DALCE produces short-lived antinociceptive actions, followed by long-term antagonism of delta receptor-mediated antinociception. The major goal of the present study was to examine the effect of DALCE on the delta cx and delta ncx binding sites in vitro and in vivo. Intracerebroventricular administration of 40 micrograms DALCE failed to decrease [3H][D-Ala2,D-Leu5]enkephalin binding to the delta cx and delta ncx binding sites. Pretreatment of membranes with DALCE in vitro greatly reduced the Bmax of the delta ncx binding site, without significantly altering the Bmax of the delta cx binding site. These findings suggest that when administered in vivo, DALCE fails to distribute uniformly throughout the brain, and that it therefore binds covalently to opioid receptors mostly in the periventricular regions. Viewed collectively, these data support the hypothesis that DALCE acts as a selective delta ncx antagonist, and that the delta ncx binding site, which is sensitive to DALCE, is most likely synonymous with the recently described delta 1 receptor.