Inhibitory Effects of Methylcellulose on Cellulose Degradation by Ruminococcus flavefaciens

Highly methylated, long-chain celluloses strongly inhibited cellulose degradation by several species of cellulolytic bacteria of ruminal origin. Specifically, the inhibitory effects of methylcellulose on the growth of Ruminococcus flavefaciens FD1 were concentration dependent, with complete inhibition at 0.1% (wt/vol). However, methylcellulose did not inhibit growth on cellobiose or cellulooligosaccharides. Mixtures of methylated cellulooligosaccharides having an average degree of polymerization of 6.7 to 9.5 inhibited cellulose degradation, but those with an average degree of polymerization of 1.0 to 4.5 did not. Similar inhibitory effects by methylcellulose and, to a lesser extent, by methyl cellulooligosaccharides were observed on cellulase activity, as measured by hydrolysis of p-nitrophenyl-beta-d-cellobioside. R. flavefaciens cultures hydrolyzed cellulooligosaccharides to cellobiose and cellotriose as final end products. Cellopentaose and cellohexaose were cleaved to these end products, but cellotetraose was also formed from cellohexaose. Methylcellulose did not inhibit hydrolysis of cellulooligosaccharides. These data are consistent with the presence of separate cellulase (beta-1,4-glucanase) and cellulodextrinase activities in R. flavefaciens.     

Effects of photoperiod and intermittent lighting on reproduction in pheasant hens

Forty 28-wk-old ring-necked pheasant hens were equally distributed among 5 treatment groups and exposed to the following light schedules for 36 wk: Treatment 1 - 16L:8D; Treatment 2 - 1L:11D:4L:8D; Treatment 3 - 1L:13D:2L:8D; Treatment 4 - 1L:14D:1L:8D; and Treatment 5 - 1L:14.5D:0.5L:8D. The number of days from stimulatory lighting to the first egg was significantly (P<0.05) greater under the intermittent schedules (20.3, 29.5, 40.3, 44.4, and 57.7 d, respectively) when the subjective daylength was shorter than 13 h. Despite the delay in initiation of laying, average egg production was higher under intermittent lighting (23.0, 36.0, 48.6, 43.8, and 42.3% or 58.0, 93.0, 122.5, 110.4, and 106.6 eggs). Patterns of oviposition indicated a tendency in the birds exposed to intermittent lighting to have synchronized laying, with the period opposite the longest scotoperiod provided by their light schedule; thus subjective daylengths of 13, 11, 10 and 9.5 h, respectively, were created. Fertility was significantly (P<0.05) lower under intermittent lighting and was apparently associated with a high proportion of eggs in the late stages of oviducal development at the time of insemination.     

Distribution of Nephrops norvegicus (L.) larvae in the western Irish Sea: an example of advective control on recruitment

Results of a survey of Nephrops norvegicus larvae conductedin the western Irish Sea during May 1984 are discussed. Thelarval distributions show a pronounced tongue of high numbersextending southward from the muddy area where they are hatched.The inferred density-driven circulation at the time of the surveyis consistent with the southward transport of larvae. BecauseN.norvegicus requires a muddy substrate for successful larvalsettlement, the processes which influence the circulation mayprovide an important control on the level of recruitment.     

Analysis of the oligosaccharides from the roots of Arnica montana L., Artemisia absinthium L., and Artemisia dracuncula L.

The oligosaccharides extracted from the roots of Arnica montana L., Artemisia absinthium L. and Artemisia dracunculus L. have been analysed by thin-layer and gel-permeation chromatography to assess their applicability as ‘guide’ substances for pharmacological activity. Differences observed in the oligosaccharide component composition of such extracts might be more related to the vegetative stage of the plants at time of harvest than to the species themselves. In addition to a series of non-reducing oligofructosides, a series of reducing inulin-type oligosaccharides was found at the initial stages of growth, whereas in later stages of growth only non-reducing oligofructosides were present. These differences have been related to different stages of biosynthetic activity within the plants.     

Party composition and dynamics inPan paniscus

The pygmy chimpanzee, or bonobo, Pan paniscus,diplays a fission-fusion social organization in which individuals associate in parties that vary in size and composition. Data from a 2-year field study of nonprovisioned P. paniscusshow that party composition varies with party size. Although females, on average, outnumber males, the proportion of males in the party increases in larger parties. This effect was not due to the greater number of known females. Both females and males will join and leave a party in the company of others, but only males appear frequently to join or leave as lone individuals. All-male parties were not observed, but all-female (nonnursery) parties were relatively common. These trends reflect greater cohesion among females than observed in P. troglodytes schweinfurthii.Cohesion between males and female P. paniscusmay increase with party size.     

Chromosomal aberrations and sister-chromatid exchanges in lymphocytes from coke oven workers

To test whether coke oven workers, an occupational group known to be at increased cancer risk, manifest increased peripheral blood chromosomal aberration frequencies, we obtained samples from a group of 30 steelworker volunteers, who had worked several years at coke oven jobs. Exposure estimates were made using measurements of work place atmospheric coal tar pitch volatiles and work histories. No statistically significant positive regression of chromosomal aberrations on exposure estimates was found. The data from the coke oven workers were also compared with the obtained concurrently and employing precisely the same laboratory protocol from a group of male Brookhaven National Laboratory employees. The coke oven workers as a group were found to have statistically significantly elevated frequencies of chromatid aberrations and of sister-chromatid exchanges.     

The H circles of Leishmania tarentolae are a unique amplifiable system of oligomeric DNAs associated with drug resistance

We have induced drug resistance against methotrexate, an inhibitor of dihydrofolate reductase, and CB3717, an inhibitor of thymidylate synthetase in a strain of Leishmania tarentolae. The drug-resistant strains contain extrachromosomal DNA circles of 68 kilobases with a 30-kilobase inverted duplication flanked by 4- and 5 kilobase unique segments. We show that these circles are highly homologous to the drug-induced H circles of L. tropica (1). All three L. tarentolae strains analyzed contain a chromosomal copy of the H region without duplication, but two of the three strains contain extrachromosomal H circles as well, predominantly present as H circle dimers in one strain and as tetramers in the other. After induction of methotrexate resistance, monomeric circles, presumably derived from the oligomers, become the major type of circle. Our results indicate that the H region represents a genomic region that can be copied at very low frequency to yield circles by a precise, but unusual mechanism under natural conditions in wild-type cells. Although superficially analogous to the episomes of bacteria, the system is without precedent in nature.     

Epitopes of an influenza viral peptide recognized by antibody at single amino acid resolution

Antibodies raised against the synthetic peptide corresponding to the carboxy-terminal 24 amino acids (305-328) of the heavy chain of the hemagglutinin molecule of influenza virus A/X-31 (H3) bind this peptide at three antigenic sites. These sites were identified by assaying binding of polyclonal BALB/c mouse antipeptide sera to the complete set of all possible di-, tri, tetra-, penta-, hexa-, hepta-, and octapeptides homologous with the 24-residue sequence. Individual epitopes were defined and essential residues identified by testing the binding of monoclonal antibodies to sets of peptide analogues in which every one of the homologous residues was replaced in turn by each of the 19 alternative genetically coded amino acids. The immunodominant epitope was shown to be a linear sequence of five amino acids, 314LKLAT318. Replacement of any one of these residues with any other amino acid resulted in loss of antibody binding, indicating that all five are essential to the interaction and that they are probably contact residues. Another antigenic site contains at least two overlapping epitopes: polyclonal sera recognize predominantly an epitope or epitopes encompassed by the linear sequence 320MRNVPEKQT328, whereas the epitope defined by a particular monoclonal antibody comprises the seven amino acids 322NVPEKQT328, of which N322, E325, and Q327 were implicated as contact residues.     

Post-embedding methods for immunolocalization of elastin and related components in tissues

Elastic tissue is composed of amorphous-appearing elastin and 12-nm diameter microfibrils, one component of which has recently been isolated and characterized as the 31 KD microfibril-associated glycoprotein MAGP. Monospecific antibodies to each of these components have been developed in this laboratory. The parameters that determine optimal localization of colloidal gold probes for post-embedding immunolabeling of elastic tissue components have been systematically studied in a variety of normal and developing tissues in mammals and birds. Protein A-gold probes stabilized with dextran have been shown to provide complexes that remain stable after more than 2 years. Conditions have been defined that permit precise localization within the extracellular matrix of antibodies to MAGP and to elastin, singly and together. Best results were obtained with acrylic resins (Lowicryl K4M or LR White). Fixation in glutaraldehyde or other aldehydic fixatives, with or without osmium, did not affect the immunostaining of elastic tissue with affinity-purified antibodies to tropoelastin, or to anti-[alpha-elastin] or anti-[alkali-insoluble elastin]. Immunostaining with the anti-MAGP antibody was less robust and was possible in tissues which had been fixed only lightly before embedding in Lowicryl K4M or LR White. This staining was enhanced by metaperiodate oxidation of the sections as well as by reduction of the tissues with sodium borohydride en bloc, followed by hyaluronidase digestion of the sections. The effects on immunostaining of a range of enzyme digestions have also been examined. Conditions have thus been defined that make possible detailed study of the relationship between elastic tissue, elastin-associated microfibrils, and other microfibrillar structures in normal and abnormal tissues during development and aging.