Antibacterial activity of rufloxacin in theStaphylococcus aureus rat granuloma pouch model

The protective effects of rufloxacin againstStaphylococcus aureus-induced infections were compared with those of ciprofloxacin in the granuloma pouch model in the rat. Two strains with different in vitro sensitivity to the drugs were studied. Rufloxacin concentrations persisted longer than ciprofloxacin in the exudate in the pouch cavity and were about eight times higher. Equal doses of rufloxacin and ciprofloxacin had similar antibacterial activities. However, rufloxacin inhibitedStaphylococcus aureus bacterial growth significantly longer than did ciprofloxacin.     

Age and growth of tarpon,Megalops atlanticus,larvae in the eastern Gulf of Mexico,with notes on relative abundance and probable spawning areas

Synopsis Leptocephali were collected in June 1981 and July 1989 over the continental shelf and slope of the Florida west coast. Tarpon larvae ranged 5.5–24.4 mm standard length (SL) and were the second most abundant leptocephalus species. Sagittae examined with compound microscopes and scanning electron microscopy had increments that were presumed to be formed daily. Increment counts made using the two microscopic techniques were not significantly different. Estimated ages ranged 2–25 days with a growth rate (± standard error) of 0.92 ± 0.04 mm d^–1 The least squares linear regression equation SL = 2.78 + 0.92 (age in days) best described the relationship between estimated age and length. Adult tarpon appear to undergo a substantial spawning migration from inshore areas frequented during spring and summer to offshore spawning grounds. Spawning occurs during May, June, and July, although the spawning season may be of greater duration.     

The picoplankton in Antarctic lakes of northern Victoria Land during summer 1989–1990

Summary Photoautotrophic picoplankton is reported from some lakes located near the Italian Antarctic station of Terra Nova. Observations, carried out by both flow cytometry on water samples and electron microscopy on micro-organisms in cultures from each lake, have confirmed the occurrence in all the environments studied of this fraction accounting, in several cases, for more than the 50% of the phytoplankton, measured as chlorophyll. Cultures of the picoplankton fraction from these waters contained known prokaryotic (Synechococcus) and eukaryotic (Chlorella) genera as well as two unidentified entities, possibly prochlorophytes.     

Permeable collagen-glycosaminoglycan cross-linked copolymers for the study of biological responses of coculturede Sertoli and spermatogenic cells

A novel collagen-glycosaminoglycan (C-GAG) substrate was developed to overcome the optical opacity of a HATF nitrocellulose substrate and to provide a more physiological permeable substrate for cocultured Sertoli and spermatogenic cells. Cocultures were prepared on optically transparent C-GAG discs attached to a polyester mesh to facilitate handling. Sertoli cells displayed a cuboidal-to-columnar shape; a large number of spermatogonia and primary spermatocytes connected by intercellular bridges were associated with basolateral and apical surfaces of Sertoli cells up to 12 days after plating. Rat Sertoli-spermatogenic cell cocultures have been used for testing the effect of toxicants on rat spermatogenesis in vitro. In our initial studies, we tested the effects of the toxicant gossypol on spermatogenic cells cocultured with Sertoli cells on nonpermeable (plastic) and permeable substrates (HATF nitrocellulose) under both standard culture conditions and during perifusion after achieving a continuous electrical-resistant cell monolayer. A selective mitochondrial structural damage was observed in spermatogenic cells (spermatogonia and spermatocytes) but not in the coexisting Sertoli cells. This damage was time- (15–60 min) and dose-dependent (0.1–10µM) and developed more rapidly under perifusion conditions. Similar mitochondrial damage was reported in the intact animal but required higher concentrations (mg) and longer administration time (months) for detection. Studies are in progress to evaluate the effect of additional toxic chemical agents on functional properties of Sertoli and spermatogenic cells in cocultures prepared on various classes of C-GAG substrates.Abbreviations C-GAG, collagen type I-glycosaminoglycans - C-C6S, collagen type I-chondroitin-6-sulfate - C-H, collagen type I-heparin     

An interspecific linkage map of mouse chromosome 15 positioned with respect to the centromere

We have used an interspecific backcross between C57BL/6J and Mus spretus to derive a molecular genetic linkage map of chromosome 15 that includes 25 molecular markers and spans 93% of the estimated length of chromosome 15. Using a second interspecific backcross that was analyzed with a centromere-specific marker, we were also able to position our map with respect to the chromosome 15 centromere. This map provides molecular access to many discrete regions on chromosome 15, thus providing a framework for establishing relationships between cloned DNA markers and known mouse mutations and for identifying homologous genes in mice and humans that may be involved in disease.     

Colocalization of Polyphenol Oxidase and Photosystem II Proteins

Polyphenol oxidase (PPO) appears to be ubiquitous in higher plants but, as yet, no function has been ascribed to it. Herein, we report on the localization of PPO based upon biochemical fractionation of chloroplast membranes in Vicia faba (broad bean) into various complexes and immunocytochemical electron microscopic investigations. Sucrose density gradient fractionations of thylakoid membranes after detergent solubilization reveals that PPO protein (by reactivity with anti-PPO antibody) and activity (based upon ability to oxidize di-dihydroxyphenylalanine) are found only in fractions enriched in photosystem II (PSII). Furthermore, of the PSII particles isolated using three different protocols utilizing several plant species, all had PPO. Immunogold localization of PPO on thin sections reveals exclusive thylakoid labeling with a distribution pattern consistent with other PSII proteins (80% grana, 20% stroma). These data strongly indicate that PPO is at least peripherally associated with the PSII complex.     

Inactivation of human and simian rotaviruses by chlorine.

The inactivation of simian rotavirus SA-11 and human rotavirus type 2 (Wa) by chlorine was compared at 4 degrees C by using single-particle virus stocks. Both virus types were usually more readily inactivated at pH 6.0 than at pH 8.0 when low chlorine concentrations (0.05 to 0.2 mg/liter) were used. A complete (5 log) reduction of both was obtained within 20 s at all pH levels when chlorine concentrations were increased to 0.3 mg/liter. Slight differences in the chlorine sensitivities of SA-11 and human rotavirus type 2 were noted but were not considered to be significant.     

Comparison of growth,exogenous auxin sensitivity,and endogenous indole-3-acetic acid content in roots ofHordeum vulgare L. and an agravitropic mutant

The chemically induced barley (Hordeum vulgare L.) mutation, agr, was found to be a simple recessive trait resulting in agravitropic roots and normal gravitropic shoots. The total seedling root growth was similar for mutant and wild-type roots, although the mutant had fewer roots per seed and greater elongation per root. Although the concentration of exogenous indole-3-acetic acid (IAA) required to reduce root growth by 50% (GR50) was 12 times greater for the agravitropic mutant, agravitropic and gravitropic roots were equally sensitive to exogenous applications of 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene acetic acid (NAA). Root IAA contents, determined by high-pressure liquid chromatography (HPLC), were not different for gravitropes and agravitropes. The greater root elongation rates, lack of sensitivity to exogenous IAA, and normal endogenous IAA levels indicate that auxin-controlled growth regulation may be altered in the mutant.