Three-dimensional structure of the tetragonal surface layer of Sporosarcina ureae.

The three-dimensional structure of the regular surface layer of Sporosarcina ureae has been determined to a resolution of 1.7 nm by electron microscopy and image reconstruction. The S-layer has p4 symmetry, a lattice constant of 12.9 nm, and a minimum thickness of 6.6 nm. The reconstruction reveals a distinct domain structure: a massive core, arms connecting adjacent unit cells, and spurs which make contact at the subsidiary fourfold symmetry axes. In the z-direction the domains appear to be arranged in three planes, creating two entirely different surface reliefs. The S-layer has a complex pattern of pores and gaps that are 2 to 3 nm wide. In addition, the secondary-structure composition has been determined by infrared spectroscopy: about 35% of the polypeptide appears to have a beta-structure conformation.     

Analysis of the bovine rumen microbiome reveals a diversity of Sus-like polysaccharide utilization loci from the bacterial phylum Bacteroidetes

Several unique Sus-like polysaccharide utilization loci (PULs) were identified from bacteria resident in bovine rumen microbiomes through functional screening of a fosmid library. The loci were phylogenetically assigned to the genus Prevotella within the phylum Bacteroidetes. These findings were augmented by a bioinformatic re-evaluation of ruminal Prevotella genomes, revealing additional loci not previously reported in the literature. Analysis of Bacteroidales-affiliated genomes reconstructed from a bovine rumen metagenome in a previous study further expanded the diversity of Sus-like PULs resident in this microbiome. Our findings suggest that Sus-like systems represent an important mechanism for degradation of a range of plant-derived glycans in ruminants.     

Comparing contributions of soil versus root colonization to variations in stomatal behavior and soil drying in mycorrhizal Sorghum bicolor and Cucurbita pepo

In prior studies we learned that colonization of soil can be as important as colonization of roots in determining mycorrhizal influence on the water relations of host plants. Here we use a path analysis modeling approach to test (a) whether quantity of hyphae in soil contributes to variations in stomatal behavior and soil drying, and (b) whether soil colonization or root colonization has a stronger influence on these stomatal and soil drying responses. Experiments were performed on Sorghum bicolor and Cucurbita pepo, with soils and roots colonized by a mixture of Glomus intraradices and Gigaspora margarita. Soil colonization generally made more significant contributions to stomatal conductance than did root colonization. Soil colonization did not make significant direct contributions to soil water potential measures (soil water potential at stomatal closure or soil drying rate), whereas root colonization did contribute a potentially important path to each. The findings further support a role for mycorrhization of the soil itself in contributing to the regulation of stomatal behavior of host plants.     

Biosynthesis and functions of eicosanoids generated by the coelomocytes of the starfish, Asterias rubens

Eicosanoids are a group of oxygenated fatty acid derivatives formed from C20 polyunsaturated fatty acids, including arachidonic and eicosapentaenoic acids. The potential of the coelomocytes of the starfish, Asterias rubens, to generate eicosanoids through the cyclooxygenase (COX) and lipoxygenase (LOX) pathways was investigated using reverse-phase high performance liquid chromatography, enzyme immunoassay and gas chromatography–mass spectrometry. The principal LOX product was identified as 8-hydroxyeicosatetraenoic acid (8-HETE) with 8-hydroxyeicosapentaenoic acid (8-HEPE) synthesised at significantly lower levels. No classical prostaglandins (PG), such as PGE₂ or PGD₂, were found to be generated by ionophore-challenged coelomocytes. Incubation of coelomocytes with lipopolysaccharides from either Escherichia coli or Salmonella abortus failed to induce an increase in generation of LOX products and the presence of 8-HETE (0–25 μM) had no significant effect on the in vitro phagocytic activity of Asterias coelomocytes. Neither indomethacin (a COX inhibitor) or esculetin (a LOX inhibitor) had any effect on the clearance of the bacterium, Vibrio splendidus, from the coelomic cavity of starfish suggesting that products of these enzymes are not involved in such coelomocyte responses to foreign particles.     

Involvement of the sun and the magnetic compass of domestic fowl in its spatial orientation

Domestic chicks are able to find a food goal at different times of day, with the sun as the only consistent visual cue. This suggests that domestic chickens may use the sun as a time-compensated compass, rather than as a beacon. An alternative explanation is that the birds might use the earth's magnetic field. In this study, we investigated the role of the sun compass in a spatial orientation task using a clock-shift procedure. Furthermore, we investigated whether domestic chickens use magnetic compass information when tested under sunny conditions.Ten ISA Brown chicks were housed in outdoor pens. A separate test arena comprised an open-topped, opaque-sided, wooden octagonal maze. Eight goal boxes with food pots were attached one to each of the arena sides. A barrier inside each goal box prevented the birds from seeing the food pot before entering. After habituation, we tested in five daily 5-min trials whether chicks were able to find food in an systematically allocated goal direction. We controlled for the use of olfactory cues and intra-maze cues. No external landmarks were visible. All tests were done under sunny conditions. Circular statistics showed that nine chicks significantly oriented goalwards using the sun as the only consistent visual cue during directional testing. Next, these nine chicks were subjected to a clock-shift procedure to test for the role of sun-compass information. The chicks were housed indoors for 6 days on a light-schedule that was 6 h ahead of the natural light–dark schedule. After clock-shifting, the birds were tested again and all birds except one were disrupted in their goalward orientation. For the second experiment, six birds were re-trained and fitted with a tiny, powerful magnet on the head to disrupt their magnetic sense. The magnets did not affect the chicks’ goalward orientation.In conclusion, although the strongest prediction of the sun-compass hypothesis (significant re-orientation after clock-shifting) was neither confirmed nor refuted, our results suggest that domestic chicks use the sun as a compass rather than as a beacon. These findings suggest that hens housed indoors in large non-cage systems may experience difficulties in orientation if adequate alternative cues are unavailable. Further research should elucidate how hens kept in non-cage systems orient in space in relation to available resources.     

The bone marrow plasma cell labeling index by flow cytometry

The bone marrow plasma cell labeling index is the most important prognostic indicator for patients with multiple myeloma. Traditionally, this test has been performed as a two color immunofluorescent microscope technique which is time consuming and requires a degree of subjectivity in its interpretation. We have assessed various adaptations of this method to flow cytometry. A bromodeoxyuridine method has been compared with a propidium iodide DNA method to detect cells in S phase and CD38-FITC has been compared with CD38-FITC + CD138-FITC and CD38-biotin + streptavidin FITC to identify plasma cells. The mean channel fluorescent intensity of the plasma cell peaks for each of these markers was 12. 7, 17.4 and 35.3 respectively demonstrating the superiority of CD38-biotin + streptavidin FITC. Analysis after propidium iodide staining provided a good correlation with the slide technique (r = 0. 71; P < 0.0001) but the bromodeoxyuridine method did not correlate with the slide method (r = 0.09; P = NS). The labeling index values obtained from either of the flow methods were greater than the microscopic method. Thus a labeling index of >4% will replace the traditional >1% threshold for identifying patients with a significantly increased labeling index. The advantages of the new method are that it takes less time to perform, is more objective and provides additional data on ploidy and cell cycle status.     

Prostaglandin F2alpha-induced estrus in ewes exhibiting estrous cycles of different duration

Effects of prostaglandin F(2alpha) (PGF(2alpha)), administered during the mid-luteal phase of the estrous cycle, were examined in ewes exhibiting estrous cycles classified as short (< or =16.5 days, short-cycle ewes, n = 10) or long (> or =18 days, long-cycle ewes, n = 9) based on the durations of two estrous cycles (cycles -2 and -1) before treatment. The ewes received (i.m.) 20mg of PGF(2alpha) on day 10 of the third estrous cycle (cycle 0) followed, 36 h later, by 25 microg of gonadotropin releasing hormone (GnRH) to time the events of ovulation. Duration of subsequent estrous cycles +1 and +2 were recorded, and then the ewes were treated with the same combination of PGF(2alpha) and GnRH beginning on day 10 of estrous cycle +3. Ovaries were recovered 6h after GnRH administration to assess development of pre-ovulatory follicles. The proportion of ewes that exhibited estrus after PGF(2alpha) and GnRH treatment on cycle 0 was not different (P > 0.05) between short- and long-cycle ewes. Onset of estrus occurred sooner (P < 0.05) after PGF(2alpha) injection in short-cycle ewes than in long-cycle ewes (1.9 +/- 0.1 days and 2.3 +/- 0.1 days, duration of cycle 0 was 11.9 and 12.3 days, respectively). Duration of estrous cycle +1 was 1.2 days longer (P < 0.01) than cycle -1 in short-cycle ewes. However, duration of estrous cycle +1 did not change (P > 0.05) after PGF(2alpha) and GnRH administration in ewes having long cycles. Pre-ovulatory follicles did not differ (P > 0.05) in numbers, diameter, layers of granulosa cells nor concentrations of progesterone and estradiol-17beta in follicular fluid between short- and long-cycle ewes after PGF(2alpha) and GnRH treatment. In conclusion, ewes having short or long estrous cycles responded differently to PGF(2alpha) and GnRH treatment with respect to the interval to onset of estrus and duration of the subsequent estrous cycle.