Influence of the surface microlayer on nutrients,chlorophyll and algal diversity of a small eutrophic bog pond

Nutrients, chlorophyll, phaeophytin and algal abundances were investigated in the surface microlayer and at subsurface depths in a small eutrophic bog pond. Nutrient levels were consistently higher in the microlayer while algal abundance was sometimes higher but sometimes lower in the microlayer than at near subsurface depths. Algal diversity values were strongly influenced by the depth of flagellate blooms, and in contrast to previous studies, diversity in the microlayer was higher than at near subsurface depths. These results are discussed in terms of weather parameters, affinity of algal species for the surface and differences between microlayer ecology in shallow and deep water systems.     

Distribution and abundance of fishes in the San Francisco Bay estuary between 1980 and 1982

In 1980 a long-term study of the fishery resources of the San Francisco Bay estuary was initiated in an effort to delineate the importance of freshwater inflow to fish and invertebrate abundance and distribution in the bay. An analysis of the trawl data collected between January 1980 and December 1982 illustrates the influence of the timing and magnitude of freshwater inflows on fish fistribution and abundance in this estuary from the perspective of monthly, seasonal and annual time scales. Normally found in the delta, Suisun Bay and San Pablo Bay during periods of increased salinity, pelagic species moved downstream after the two peak flows studied, while demersal species usually found in Central San Francisco Bay moved upstream. Such upstream movements may be due in part to transport by strong density-driven currents.Timing and magnitude of monthly catches of some species varied on a seasonal cycle coincident with variations of freshwater inflow. Most species, especially the marine species, showed no consistent cycle of monthly catches. In the wet years of 1980 and 1982 the distributions of freshwater, estuarine and anadromous species were extended downstream into San Pablo, Central and South San Francisco Bays and some marine species, including the flatfish, were more abundant in the upstream areas. In the dry year of 1981 when bay salinities were higher, few marine species extended their distributions upstream into San Pablo and Suisun Bays. Jacksmelt was the only fish of the 15 most abundant species with its peak abundance in 1981. Most marine species were more abundant in the San Francisco Bay estuary in the wet years.     

Evolution and Extinction of Transposable Elements in Mendelian Populations

A model of the evolution of a transposable element family in a Mendelian host population is proposed that incorporates heritable phenotypic mutations in the elements. The temporal behavior of the numbers of mutant and wild-type elements is studied, and the expected extinction time of the transposable element family is examined. Our results indicate that, if the mutant can be transposed equally well in the presence of the wild type, then it can be expected to be found in preponderance, whereas elements, such as retroviruses, where the transposing genome and its phenotypic expression are coupled, may be characterized by a low mutant frequency.     

Phosphorylation of ribosomal and ribosome-associated proteins in isoproterenol-induced cardiac hypertrophy

Cardiac hypertrophy in adult rabbits was induced by subcutaneous injection of isoproterenol. The rate of [3H]leucine incorporation into acid insoluble material was increased and the extent of [32P]phosphate incorporation into several ribosomal proteins was altered. Specifically, a ribosomal protein with a molecular weight of 32,000 from the 40S ribosomal subunit showed a five-fold increase in phosphate incorporation in the hypertrophic heart whereas a protein with a molecular weight of 28,000 from the 60S subunit showed a four-fold decrease. Phosphorylation of ribosome-associated proteins, which could be removed from ribosomes with 0.72 M KCl, was also changed in the hypertrophic hearts. Six major phosphoproteins (with molecular weights 62,000, 49,000, 36,000, 30,000, 20,000 and 12,000) were detected in both the normal and the hypertrophic hearts. Phosphorylation of the 62 K and the 49 K protein was increased by two- and three-fold, respectively, in the hypertrophic hearts, whereas phosphorylation of the 36 K and the 30 K protein decreased by two-fold. The level of phosphorylation of the 20 K and the 12 K protein was not significantly changed in hypertrophic hearts.     

Alcaligenes eutrophus CH34 is a facultative chemolithotroph with plasmid-bound resistance to heavy metals.

Alcaligenes eutrophus strain CH34, which was isolated as a bacterium resistant to cobalt, zinc, and cadmium ions, shares with A. eutrophus strain H16 the ability to grow lithoautotrophically on molecular hydrogen, to form a cytoplasmic NAD-reducing and a membrane-bound hydrogenase, and most metabolic attributes; however, it does not grow on fructose. Strain CH34 contains two plasmids, pMOL28 (163 kilobases) specifying nickel, mercury, and cobalt resistance and pMOL30 (238 kilobases) specifying zinc, cadmium, mercury, and cobalt resistance. The plasmids are self-transmissible in homologous matings, but at low frequencies. The transfer frequency was strongly increased with IncP1 plasmids RP4 and pUZ8 as helper plasmids. The phenotypes of the wild type, cured strains, and transconjugants are characterized by the following MICs (Micromolar) in strains with the indicated phenotypes: Nic+, 2.5; Nic-, 0.6; Cob+A, 5.0; Cob+B, 20.0; Cob-, less than 0.07; Zin+, 12.0; Zin-, 0.6; Cad+, 2.5; and Cad-, 0.6. Plasmid-free cells of strain CH34 are still able to grow lithoautotrophically and to form both hydrogenases, indicating that the hydrogenase genes are located on the chromosome, in contrast to the Hox structural genes of strain H16, which are located on the megaplasmid pHG1 (450 kilobases).     

Rat liver glutathione S-transferases. Construction of a cDNA clone complementary to a Yc mRNA and prediction of the complete amino acid sequence of a Yc subunit

Using polysomal immunoselected rat liver glutathione S-transferase mRNAs, we have constructed cDNA clones using DNA polymerase I, RNase H, and Escherichia coli ligase (NAD+)-mediated second strand cDNA synthesis as described by Gubler and Hoffman (Gubler, U., and Hoffman, B. S. (1983) Gene 25, 263-269). Recombinant clone, pGTB42, contained a cDNA insert of 900 base pairs whose 3' end showed specificity for the Yc mRNA in hybrid-select translation experiments. The nucleotide sequence of pGTB42 has been determined, and the complete amino acid sequence of a Yc subunit has been deduced. The cDNA clone contains an open reading frame of 663 nucleotides encoding a polypeptide comprising 221 amino acids with a molecular weight of 25,322. The NH2-terminal sequence deduced from pGTB42 is in agreement with the first 39 amino acids determined for a Ya-Yc heterodimer by conventional protein-sequencing techniques. A comparison of the nucleotide sequence of pGTB42 with the sequence of a Ya clone, pGTB38, described previously by our laboratory (Pickett, C. B., Telakowski-Hopkins, C. A., Ding, G. J.-F., Argenbright, L., and Lu, A.Y.H. (1984) J. Biol. Chem. 259, 5182-5188) reveals a sequence homology of 66% over the same regions of both clones; however, the 5'- and 3'-untranslated regions of the Ya and Yc mRNAs are totally divergent in their sequences. The overall amino acid sequence homology between the Ya and Yc subunits is 68%, however, the NH2-terminal domain is more highly conserved than the middle or carboxyl-terminal domains. Our data suggest that the Ya and Yc subunits of the rat liver glutathione S-transferases are products of two different mRNAs which are derived from two related yet different genes.     

Biogenic amine degradation by homogenates of the bulb mite,Rhizoglyphus echinopus (Fumouze and Robin) (Acari: Astigmata: Acaridae)

Whole homogenates of bulb mites rapidly metabolized 2-phenylethylamine (PEA) but were appreciably less active against tryptamine, 5-hydroxytryptamine, and dopamine; no degradation of octopamine was detected. The rate of PEA degradation by bulb mites was dependent upon both substrate and homogenate concentrations. PEA degradation was inhibited by pargyline (pI₅₀, 6.7), tranylcypromine (pI_{50 6.2}), and harmaline (pI_{50 4.1}), but not by 5-chloro-2,4-dimethoxyformanilide. These results suggested that PEA metabolism by bulb mite homogenates was catalyzed mainly by Type B monoamine oxidase.Contribution from the Missouri Agricultural Experiment Station, Columbia, MO. Journal Series No. 9777     

Regeneration of the arterial wall in microporous,compliant, biodegradable vascular grafts after implantation into the rat abdominal aorta

Summary The ultrastructure of a new type of vascular graft, prepared from a mixture of polyurethane (95 weight %) and poly-L-lactic acid (5 weight %), was examined six weeks after implantation into the abdominal aorta of rats. These microporous, compliant, biodegradable, vascular grafts function as temporary scaffolds for the regeneration of the arterial wall.Smooth muscle cells, covering the grafts, regenerated a neo-media underneath an almost completely regenerated endothelial layer (neo-intima). These smooth muscle cells varied in morphology from normal smooth muscle cells to myofibroblasts. They were surrounded by elastic laminae and collagen fibers.Macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries were present in the disintegrating graft lattices. The epithelioid cells and multinucleated giant cells engulfed polymer particles of the disintegrating grafts.The regeneration of the endothelial and smooth muscle cells is similar to the natural response of arterial tissue upon injury. The presence of macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries in the graft lattices resembles the natural response of tissue against foreign body implants. Both of these responses result in the formation of a neo-artery that possesses sufficient strength, compliance and thromboresistance to function as a small caliber arterial substitute.Supported by Grant nr. 82.042 from the Dutch Heart Foundation     

Analysis of the sheep MHC using HLA class I,II, and C4 cDNA probes

Four cDNA probes for the human major histocompatibility complex (MHC) were used to investigate the sheep MHC, in conjunction with serological typing for ovine lymphocyte antigen (OLA). Lymphocytes from a family (two parents and five offspring) of Romanov sheep were subjected to genomic DNA digestion by the restriction endonuclease Eco RI, followed by gel electrophoresis. A single Southern blot representing all seven individuals was then consecutively hybridized with the class I, alpha-DC, beta-DR, and C4 probes, which were originally designed to identify HLA class I, class II (DC and DR), and C4 products, respectively. Using each of the three class I/class II probes, several bands showing DNA polymorphism were detected. The segregation of these bands in the five offspring exactly paralleled the OLA haplotype segregation established by serological typing. A further eight individuals carrying haplotypes which were phenotypically identical to those in the above-mentioned family showed bands in the corresponding positions when tested with the same three probes. Using the C4 probe, no polymorphism was detected in these fifteen individuals.Abbreviations used in this paper MHC major histocompatibility complex - OLA ovine lymphocyte antigen - kbp kilobase pair(s) - MLR mixed lymphocyte reaction - RFLP restriction fragment length polymorphism