Microbiological evaluation of the intraruminal in sacculus digestion technique

The influence of nature of the feed sample, feeding frequency and pore size on the influx of bacteria and protozoa into synthetic fiber bags suspended in the rumens of sheep fed different diets was studied. Counts of total culturable bacteria in bags with a pore size of 10 microns were less than 30% of the ruminal counts for animals that were fed the lucerne hay and high-roughage diets. The maximum count (62 and 82% of the ruminal count) for these specific diets was obtained by using bags with a pore size of 53 microns. Protozoal counts in bags with pore sizes of 30 and 53 microns were equal to or higher than the ruminal counts for the lucerne hay and high-roughage diets but less than half of the ruminal count for the low-roughage diet. An interaction between incubation time, feeding frequency of the host animals, and the microbial populations developing inside the bags was also demonstrated. The results clearly show that the microbial population inside the bag differed from that of the surrounding ruminal ingesta and that caution must be taken in interpreting results on feed evaluation and especially on rates of degradation when using the in sacculus technique. Factors influencing the influx of bacteria and protozoa into bags with different pore sizes and containing a variety of substrates are discussed together with suggestions for the use of this technique.     

Binding of [14C]inosine to gustatory tissues of the turbot, Scophthalmus maximus

Reversible specific binding of [14C]inosine has been demonstrated in turbot (Scophthalmus maximus) buccal tissues rich in taste buds. A highly significant correlation was found for a series of nucleosides and nucleotides between their feeding stimulant activity and their ability to displace bound [14C]inosine. It is concluded that the binding of inosine is the first step in the gustatory process.     

3,5-Diethoxycarbonyl-2,6-dimethyl-4-ethyl-1,4-dihydropyridine inactivates rat liver cytochrome P-450c, but not its orthologue, rabbit lung form 6

Various rat liver cytochrome P-450 (P-450) isozymes are targets for mechanism-based inactivation by 3,5-diethoxycarbonyl-2,6-dimethyl-4-ethyl-1,4- dihydropyridine (4-ethyl DDC). Unlike rat liver, which contains multiple P-450 isozymes, rabbit lung contains only three major isozymes referred to as forms 2, 5, and 6. We have examined the ability of 4-ethyl DDC to destroy P-450 heme in hepatic and pulmonary microsomes from untreated and beta-naphthoflavone (beta NF)-treated rabbits. This compound destroyed 31% of the P-450 in either hepatic microsomal preparation, but was ineffective at lowering P-450 and heme levels in pulmonary microsomes when examined at a range of concentrations (0.45-5.0 mM). These data suggest that rabbit pulmonary P-450 forms 2, 5, and 6 are not targets for destruction by 4-ethyl DDC, despite the ability of this compound to inactivate rat liver P-450c, the orthologue of rabbit lung form 6.     

The recognition, distribution and ultrastructure of hydrozoan nerve elements

Silver stained Cordylophora were examined by light and electron microscopy, which provided a general picture of nerve cell forms and distribution for comparison with electron micrographs of osmium-fixed tissues from the same hydroid. Muscle, nerve and neurosensory components were studied in the nectophore of Nanomia (O. Siphonophora) and in the hydromedusae Sarsia and Euphysa by means of vital staining and optical and electron microscopy of epon sections; particular attention was given to relationships and interconnections between the cellular elements of the two marginal nerve rings. Mitochondrial size, numbers and types of vesicles and the occurrence of neurotubules and of parts of sensory cilia may provide useful ultrastructural clues for recognizing nerve elements, but serial sections are often needed to make identification conclusive. In Cordylophora and Nanomia, some neurites contain massed A vesicles (membrane-bounded dense granules) suggestive of neurosecretion (cf. reports on Hydra). However, a small type of A vesicle also occurs at synapses in Sarsia, indicating a probable role here in junctional transmission. Vesicles occur on both sides of some synapses (as previously reported for Cyanea) but on one side only in others, these being the first examples of polarized junctional ultrastructure in coelenterates.     

A medium for the rapid growth and detection of moulds

A method is described for encouraging rapid germination and growth of mould propagules and enhancement of their detection. This inovles the design of a new growth medium Apple Pulp Gelatin (APG) which contains an optical brightener.     

Phosphatic spicules in the nematocyst batteries of Nanomia cara (Hydrozoa,Siphonophora)

Summary The complex, erupting nematocyst batteries of Nanomia cara are described. In addition to the cnidoband, the battery has a central axis containing longitudinal muscles and nerves that run right through to the terminal filament. In addition, an elastic strand lies coiled within the battery. After eruption of the battery, this strand keeps the prey attached to the tentacle. The strand bears hook-like spicules, equipped with barbs that project beyond the surface. Electron microscopy shows that the elastic strand is a mesogloeal structure tunnelled through and through with cellular processes deriving from both ectoderm and endoderm and that the spicules lie in cellular pockets in the interior of the elastic strand. There is nothing in the structure of the spicules or their cellular sheaths to suggest an origin from nematocysts. Energy dispersive X-ray microanalysis shows strong peaks for calcium and for phosphorus in the spicules, indicating that the mineral present in them is an apatite. An organic matrix is also found in the form of fine filaments and a granular axial structure. The spicules are arranged in a linear series along the elastic strand showing progressive increase in size and structural elaboration.     

β-Glucanase expression by Ruminococcus flavefaciens FD-1

Abstract Ruminococcus flavefaciens has been hypothesized to produce cellulase constitutively. We have studied the effect of carbon source, either cellobiose or cellulose, on the production of cellulase in batch cultures of R. flavefaciens FD-1. Total CMCase and ¹⁴C-cellulase activity was approximately 2-fold higher in cellobiose grown cells than in cellulose grown cells, whereas p-nitrophenyl-β- d -cellobiosidase (PNPCase) activity was not affected by culture conditions. The addition of cellulose to cells growing on cellobiose did not alter the amount or rate of PNPCase and ¹⁴C-cellulase production. Northern blot analysis of mRNAs produced by R. flavefaciens FD-1 grown using either cellobiose or cellulose as the substrate indicated that two of the four β-glucanase genes cloned from R. flavefaciens FD-1 were only expressed in cells grown with cellulose as the substrate. Although the adherence of cells and cellulase enzyme to native cellulose can complicate interpretations of these data, the results indicate that cellulase synthesis by R. flavefaciens is differentially regulated by carbon source.     

Bonafide,type-specific human papillomavirus persistence among HIV-positive pregnant women: predictive value for cytological abnormalities,a longitudinal cohort study

This study investigated the rate of human papillomavirus (HPV) persistence, associated risk factors, and predictors of cytological alteration outcomes in a cohort of human immunodeficiency virus-infected pregnant women over an 18-month period. HPV was typed through L1 gene sequencing in cervical smears collected during gestation and at 12 months after delivery. Outcomes were defined as nonpersistence (clearance of the HPV in the 2nd sample), re-infection (detection of different types of HPV in the 2 samples), and type-specific HPV persistence (the same HPV type found in both samples). An unfavourable cytological outcome was considered when the second exam showed progression to squamous intraepithelial lesion or high squamous intraepithelial lesion. Ninety patients were studied. HPV DNA persistence occurred in 50% of the cases composed of type-specific persistence (30%) or re-infection (20%). A low CD4⁺T-cell count at entry was a risk factor for type-specific, re-infection, or HPV DNA persistence. The odds ratio (OR) was almost three times higher in the type-specific group when compared with the re-infection group (OR = 2.8; 95% confidence interval: 0.43-22.79). Our findings show that bonafide (type-specific) HPV persistence is a stronger predictor for the development of cytological abnormalities, highlighting the need for HPV typing as opposed to HPV DNA testing in the clinical setting.