Uptake and utilization of14C-glycine by embryos ofSebastes melanops

Synopsis The ability of embryos of the viviparous scorpaenidSebastes melanops to take up nutrients from an exogenous substrate was demonstrated by incubating embryos at various stages of development (18–30 days after fertilization) in¹⁴C-labeled glycine for 24 h. Uptake was highest for embryos at the latest stages (28–30 days) and increased at a linear rate during the incubation period. Nutrient uptake was not time dependent in embryos at the early stages (18–22 days). Nutrient utilization byS. melanops embryos was measured by the oxidation of¹⁴C-labeled glycine to¹⁴CO₂. The amount of respired¹⁴CO₂ by the oldest embryos increased significantly at a linear rate over the 24 h incubation period. There was no evidence of nutrient utilization by the youngest embryos. The developmental changes we observed in the uptake and utilization of exogenous glycine are supported by our previous findings that the oldest embryos have fully developed mouths and guts, and require additional nutrition from intraovarian sources at this stage of development.     

Isolation of a New Polysaccharide-Digesting Bacterium from a Salt Marsh

A new marine bacterium that digested a variety of storage and structural polysaccharides, including agar, was isolated. Strain 2-40 is a nonfermentative gram-negative, polarly flagellated rod that sometimes grew as a filamentous helix and secreted a melaninlike pigment. Its characteristics conform to those of no previously described species.     

Microbially Mediated Mn(II) Oxidation in an Oligotrophic Arctic Lake

Rates of oxidation of Mn(II) were measured by an in situ incubation technique in the water column of Toolik Lake, Alaska. Measured rates were lower than those observed in other aquatic systems but were sufficient to oxidize all Mn(II) in the lake within a 3-month period. Measured rates compared favorably with rates estimated from a previous study of the geochemical cycling of Mn in Toolik Lake. The Mn(II) oxidation was largely microbially mediated, as indicated by inhibition of oxidation rates by sodium azide. Azide had been previously demonstrated to be a suitable microbial poison for studying Mn(II) oxidation in seawater. This study demonstrates that azide is also a suitable poison for freshwaters and that it inhibits microbial but not abiotic oxidation of Mn(II). Manganese(II) oxidation rates were similar during cold, under-ice conditions in early spring and during warmer summer conditions. This observation suggests that Mn(II) concentration, rather than temperature or oxygen concentration, is the most important factor regulating Mn(II) oxidation rates in Toolik Lake.     

Inactivation of gamma-aminobutyric acid aminotransferase by (Z)-4-amino-2-fluorobut-2-enoic acid

(Z)-4-Amino-2-fluorobut-2-enoic acid (1) is shown to be a mechanism-based inactivator of pig brain gamma-aminobutyric acid aminotransferase. Approximately 750 inactivator molecules are consumed prior to complete enzyme inactivation. Concurrent with enzyme inactivation is the release of 708 +/- 79 fluoride ions; transamination occurs 737 +/- 15 times per inactivation event. Inactivation of [3H]pyridoxal 5'-phosphate ([3H]PLP) reconstituted GABA aminotransferase by 1 followed by denaturation releases [3H]PMP with no radioactivity remaining attached to the protein. A similar experiment carried out with 4-amino-5-fluoropent-2-enoic acid [Silverman, R. B., Invergo, B. J., & Mathew, J. (1986) J. Med. Chem. 29, 1840-1846] as the inactivator produces no [3H]PMP; rather, another radioactive species is released. These results support an inactivation mechanism for 1 that involves normal catalytic isomerization followed by active site nucleophilic attack on the activated Michael acceptor. A general hypothesis for predicting the inactivation mechanism (Michael addition vs enamine addition) of GABA aminotransferase inactivators is proposed.     

Reproductive physiology of the clouded leopard: II. A circannual analysis of adrenal-pituitary-testicular relationships during electroejaculation or after an adrenocorticotropin hormone challenge

A circannual analysis was made of serum cortisol, luteinizing hormone (LH), and testosterone concentrations in the male clouded leopard (Neofelis nebulosa). Group I males (n = 4), maintained in a standardized environment, were bled serially during a regimented anesthesia/electroejaculation episode occurring monthly (beginning in January, ending in December). Additional sampling intervals were conducted under anesthesia only (control, n = 8), anesthesia plus a single adrenocorticotropin hormone challenge (ACTH, Cortrosyn, n = 4), or anesthesia plus a single 25 micrograms injection of gonadotropin-releasing hormone (GnRH, Gonadorelin, n = 4). Group II males (n = 6) from various zoological collections were sampled serially under the same semen collection conditions on one random occasion within the year. Serum cortisol levels were 2 times greater than values measured in comparable studies involving other felid species. Cortisol concentrations were similar during electroejaculation and control (anesthesia only) episodes, and mean levels did not rise as a result of semen collection. Adrenocorticotropin caused an immediate rise in cortisol to levels at least 1.5 times greater than electroejaculated or control counterparts. Mean concentrations of basal cortisol in individual males gradually increased as the year progressed, possibly as a consequence of repeated psychogenic stress. Between seasons, there were no differences in mean LH; however, testosterone levels were greater (p less than 0.05) in the winter compared to all other seasons. There were no differences (p greater than 0.05) between individual males in secretory patterns or mean concentrations of cortisol, LH, or testosterone. Within males, distinct temporal fluctuations were observed in both LH and testosterone during the approximately 80-min sampling interval. Neither LH nor testosterone profiles appeared affected by cortisol patterns during electroejaculation or after an ACTH challenge. A bolus of GnRH induced a marked rise in serum LH and testosterone within 15 and 30 min respectively, indicating that these two hormones were coupled. Both LH and testosterone profiles in Group II males mimicked those in Group I; concentrations of cortisol in Group II males immobilized on one occasion were similar to those of Group I animals sampled from January-May but appeared to be less than values measured from June-December. These data demonstrate that the clouded leopard, compared to other felids, produces markedly elevated concentrations of cortisol, which are likely related to an aggressive behavioral temperament.(ABSTRACT TRUNCATED AT 400 WORDS)     

A new subspecies and new combinations in Comarostaphylis (Ericaceae)

Comarostaphylis spinulosa subsp.glandulifera is described from the mountains of Oaxaca and Puebla, Mexico. Four new combinations inComarostaphylis are also made:C. arbutoides subsp.costaricensis, C. discolor subsp.rupestris, C. polifolia subsp.minor, andC. spinulosa.Arctostaphylos glabrata, A. rupestris, andA. spinulosa are lectotypified and the status ofC. polifolia is discussed.     

DNA sequence evidence for polymorphic forms of human serum amyloid A (SAA)

Serum amyloid A (SAA) is an acute-phase reactant and precursor to amyloid A protein, the major constituent of the fibril deposits of reactive amyloidosis. The factors determining whether the 104-amino acid SAA molecule is converted into the 76-amino acid amyloid A protein and deposited as fibrils are not known. As an initial step toward investigating the possibility that a particular primary structure of SAA is involved in amyloid formation, we have cloned and determined the nucleotide sequence of human SAA-specific cDNAs. The first clone, selected using an oligonucleotide probe, was shown to encode the signal peptide and amino-terminal region of SAA. The cDNA of this clone served as probe in the selection of two distinct, full-length SAA cDNAs, initially differentiated by the presence (pSAA21) or absence (pSAA82) of a PstI site in the coding sequence. The complete nucleotide sequence of pSAA82 cDNA was determined. Since there appear to be multiple human SAA alleles, it is conceivable that their differential expression is important to amyloid formation.