Angiogenic activity of maternal and fetal placental tissues of ewes throughout gestation

In Study 1, explants of caruncular and intercaruncular endometrium and fetal membrane were collected from ewes (5-6/day) on Days 11-13, 16-18 and 21-23 after mating and Days 10-12 after oestrus, and incubated for 24 h. Explant-conditioned media were evaluated for their effects on endothelial cell proliferation. Both caruncular and intercaruncular endometrium secreted factor(s) which stimulated endothelial cell proliferation, and which appeared to be greater than 100 x 10(3) Mr and heat-labile. In Study 2, conditioned media from explant incubations of caruncular and intercaruncular endometrium, cotyledon and intercotyledonary fetal membrane obtained from ewes (6-7/day) on Days 40, 65, 90, 115 and 140 after mating were evaluated for their effects on endothelial cell proliferation. Caruncular and intercaruncular endometrium and intercotyledonary fetal membrane secreted factor(s) which inhibited endothelial cell proliferation. Media from cotyledonary explants tended to stimulate endothelial cell proliferation on Day 115. Conditioned media from cotyledonary explants obtained from 3 additional ewes at Day 120 of gestation stimulated endothelial cell proliferation, and this activity also appeared to be greater than 100 x 10(3) Mr. Placental angiogenesis in ewes therefore appears to be modulated by both maternal and fetal placental tissues via stimulatory and inhibitory factors.     

Characteristics and N-terminal amino acid sequence of a manganese peroxidase purified from Lentinula edodes cultures grown on a commercial wood substrate

Summary Extracellular culture filtrates from ligninolytic cultures of the lignin-degrading basidiomycete Lentinula (syn. Lentinus) edodes (Berk.) Pegler contained one major peroxidase when grown on a commercial oak-wood substrate. The peroxidase was purified by polyethylenimine clarification, anion-exchange chromatography, and hydrophobic-interaction HPLC. The enzyme (MnP1) was a heme-iron protein with an apparent molecular weight of 44 600 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and an isoelectric point of pH 3.2. The native enzyme had an absorption maximum at 407 nm, which shifted to 420 nm upon H₂O₂ addition. The pyridine-hemochrome-absorption spectrum indicated that one heme group was present per enzyme as protoporphyrin IX. N-terminal amino acid sequencing showed that MnP1 had higher sequence homology with manganese peroxidases than with lignin peroxidases reported from Phanerochaete chrysosporium. L. edodes MnP1 was capable of oxidizing lignin and lignin-model compounds in the presence of manganese and H₂O₂.On leave from the Department of Biochemistry, University of Otago, P. O. Box 56, Dunedin, New Zealand.Research carried out while a visiting scientist at the USDA Forest Products Laboratory from the National Chemistry Laboratory, Pune, India 41 1008 Offprint requests to: I. T. Forrester     

Analysis of the traLEKBP sequence and the TraP protein from three F-like plasmids: F, R100-1 and ColB2.

The sequence of a region of the F plasmid containing the traLEKBP genes involved in plasmid transfer was compared to the equivalent regions of two IncFII plasmids, R100-1 and ColB2. The traLEK gene products of all three plasmids were virtually identical, with the most changes occurring in TraE. The TraB genes were also nearly identical except for an 11-codon extension at the 3' end of the R100-1 traB gene. The TraP protein of R100-l differed from those of F and ColB2 at its N terminus, while the ColB2 TraP protein contained a change of sequence in a predicted loop which was shown to be exposed in the periplasmic space by TnphoA mutagenesis. The effect of the altered TraP sequences was determined by complementing a traP mutant with clones expressing the traKBP genes of F, R100-1, and ColB2. The traP mutation in pOX38 (pOX38-traP474), a derivative of F, was found to have little effect on pilus production, pilus retraction, and filamentous phage growth and only a moderate effect on transfer. The transfer ability of pOX38-traP474 was shown to be affected by mutations in the rfa (lipopolysaccharide) locus and in ompA in the recipient cell in a manner similar to that for the wild-type pOX38-Km plasmid itself and could be complemented with the traP analogs from R100-1 and ColB2 to give an F-like phenotype. Thus, the TraP protein appears to play a minor role in conjugation and may interact with TraB, which varies in sequence along with TraP, in order to stabilize the proposed transmembrane complex formed by the tra operon products.     

The prevalence of gentamicin 2'-N-acetyltransferase in the Proteeae and its role in the O-acetylation of peptidoglycan

Abstract The prevalence of aac(2')-Ia , a gene coding for gentamicin 2'-JV-acetyltransferase in Providenda stuartii , among species of the Proteeae was investigated to determine if it is a common resistance factor and whether the correlation observed in P. stuartii between its expression and the levels of peptidoglycan O -acetylation represents a general feature of bacteria producing this form of modified peptidoglycan. An evaluation of the MICs of gentamicin for each of the species of the Proteeae did not reveal any apparent relationship between resistance and the degree of O-acetylation of peptidoglycan. The entire aac(2')-Ia gene was used as a probe in Southern hybridization experiments against genomic DNA from each species of the Proteeae. A sequence with strong homology to aac(2')-Ia was present only in Proteus penneri while weak hybridization was also observed to the restriction digested DNA from Providenda rettgeri . Other bacteria that O -acetylate peptidoglycan were also screened with this probe and a homologous DNA sequence was only found in Neisseria subflava . These data suggest that AAC(2')-Ia may contribute to the rO -acetylation of peptidoglycan in P. stuartii , but a more specific enzyme must also be produced for this function.     

Distribution and breeding biology of offshore cichlids in Lake Malawi/ Niassa

Synopsis Lake Malawi/Niassa is the second largest rift valley lake in Africa, with an area of 28 800 km², and an average and maximum depth of 292 m and>700 m, respectively. The lake is well known for the great diversity of fish occurring in the inshore zone. However, the offshore fish community is poorly documented. To rectify this, regular sampling was undertaken over two years, using trawl and gillnets at six offshore locations. This paper reports on the species composition, spatial distribution and breeding biology of the dominant cichlids species from the offshore pelagic zone. Cichlids formed approximately 88% of the offshore fish biomass. Most abundant were two species of zooplanktivores in the genus Diplotaxodon that made up 71% of the offshore fish biomass. An undescribed species, given the cheironym D. bigeye, was mainly found at a depth of 220 m during the day, but moved into near surface waters at night when the moon was full. This species was absent from the shallow regions of the lake. The most abundant offshore species was D. limnothrissa, which was distributed evenly throughout the lake to depths of 220 m. A less common offshore zooplanktivore was Copadichromis quadrimaculatus that formed 5% of the biomass and was confined to the upper 100 m of the water column. The main piscivores were in the genus Rhamphochromis and formed approximately 10% of the offshore fish biomass. The two dominant taxa were R. longiceps and the large Rhamphochromis group, and both were more common in the southern half of the lake. The former occurred mainly in the upper 100 m of the water column and the latter mainly at depths of 100–150 m. The length at maturity and fecundity for the dominant offshore species were estimated and seasonal breeding cycles determined from gonad activity and gonado-somatic indices.     

Two-bond C-C spin-coupling constants in carbohydrates: effect of structure on coupling magnitude and sign

An empirical projection method is described to predict the magnitudes and signs of two-bond ¹³C-¹³C spin-coupling constants (²J_CC) in aldopyranosyl rings. The method has been applied primarily to the interpretation of ²J_CCC values, although the behavior of ²J_COC has also been examined in light of the new approach, producing results which may prove useful in the conformational analysis of O-glycosidic linkages in oligosaccharides. High-level ab initio calculations of ²J_CC values in model compounds were found to be in agreement with the predictions.     

Genic diversity in Red River pupfish Cyprinodon rubrofluviatilis (Atheriniformes: Cyprinodontidae) and its implications for the conservation genetics of the species

Starch gel electrophoresis of proteins was used to study geographic variation at 26 gene loci in the Red River pupfish ( Cyprinodon rubrofluviatílís ), a species restricted to west Texas and Oklahoma. Marked differences were detected between populations in the Red and Brazos river drainages, with fixed or nearly fixed differences occurring at five gene loci. In addition, mean heterozygosity was uniformly high for the Red River form ( = 0·076–0·101) while samples of the Brazos River form were genetically depauperate ( =0·00–0·017). Introduced populations in the South Canadian and Colorado river drainages appear to have been derived from the Red River drainage. The presence of alleles diagnostic of the Red and Brazos river forms supports the suggestion from previous work that they may represent cryptic species. Regardless of taxonomy, however, the presence of two genetically distinct forms must be taken into consideration by those concerned with maintenance of biotic diversity.     

Floral expression of a gene encoding an E2-relatedubiquitin-conjugating protein from Arabidopsis thaliana

An Arabidopsis thaliana gene (UBC6) encoding a homologue to ubiquitin-conjugating enzymes has been isolated which is capable of encoding a protein of 183 amino acids of ca. 21 kDa. Northern analysis indicates that the gene is expressed in flowers, seeds and, to a somewhat lesser extent, in 10-day seedlings but not in mature leaves, callus and pre-flowering plants. This pattern of expression is confirmed using transgenic Arabidopsis plants containing a UBC6 promoter-GUS gene fusion construct. These plants displey GUS activity in mature anthers prior to dehiscence, in developing embryos, sepals and the style after pollination.