Electroejaculation and semen analysis in the La Plata three‐banded armadillo (Tolypeutes matacus)

The objectives of this study were to: 1) develop an electroejaculation procedure for collecting semen from the La Plata three‐banded armadillo (Tolypeutes matacus), and 2) characterize basal reproductive traits, including sperm concentration, motility, morphology, acrosomal status, and viability. Three male armadillos were each electroejaculated on one to five occasions. Fluid containing spermatozoa was recovered during each attempt, and high proportions (>75%) of morphologically normal spermatozoa were seen in all analyzed samples. Two fluorescent stains (FITC‐PNA and Hoechst 33258) appeared to be effective for assessing acrosomal status and viability, respectively, in this species. Sperm concentration and motility were usually low, and urine contamination was a persistent problem—possibly due to anesthesia, unique reproductive anatomy, and/or improper probe placement. Poor sperm recovery, urine contamination, and sensitivity of spermatozoa to culture medium must be addressed before electroejaculation can be used routinely in the La Plata three‐banded armadillo. Zoo Biol 21:481–487, 2002. © 2002 Wiley‐Liss, Inc.     

The Changing Face of Natural Resources Students,Education, and the Profession

ABSTRACT There are many challenges facing natural resources programs in North American higher education today. Pressures exerted by a new generation of students, changing workplace requirements (including undergraduate core-knowledge requirements), and an increasingly specialized professoriate are great but not insurmountable. We discuss each of these issues and pose potential solutions to address each including adopting new pedagogical techniques for content delivery (e.g., adapting courses to be inclusive of new technologies), revising curriculum to meet the needs of a new suite of learners (e.g., developing curricula that allow structured flexibility of choices, designing a core curriculum that is a mix of single-discipline courses and courses that integrate across disciplines), and new strategies for faculty engagement in discipline-specific survey courses. By remaining deliberate and effective in our pursuit of quality higher education we have the opportunity to ensure we are delivering the best possible education to the future professionals of our disciplines.     

Structural Basis of Glycan Recognition in Globally Predominant Human P[8] Rotavirus

Rotavirus(RV)causes acute gastroenteritis in infants and children worldwide.Recent studies showed that glycans such as histo-blood group antigens(HBGAs)function as cell attachment factors affecting RV host susceptibility and prevalence.P[8]is the predominant RV genotype in humans,but the structural basis of how P[8]RVs interact with glycan ligands remains elusive.In this study,we characterized the interactions between P[8]VP8~*s and glycans which showed that VP8~*,the RV glycan binding domain,recognized both mucin core 2 and H type 1 antigens according to the ELISA-based oligosaccharide binding assays.Importantly,we determined the structural basis of P[8]RV-glycans interaction from the crystal structures of a Rotateq P[8]VP8~*in complex with core 2 and H type 1 glycans at 1.82.3 ?,respectively,revealing a common binding pocket and similar binding mode.Structural and sequence analysis demonstrated that the glycan binding site is conserved among RVs in the P[Ⅱ]genogroup,while genotype-specific amino acid variations determined different glycan binding preference.Our data elucidated the detailed structural basis of the interactions between human P[8]RVs and different host glycan factors,shedding light on RV infection,epidemiology,and development of anti-viral agents.     

Diurnal foraging ant–tree co-occurrence networks are similar between canopy and understorey in a Neotropical rain forest

Discussion of the vertical stratification of organisms in tropical forests has traditionally focused on species distribution. Most studies have shown that, due to differences in abiotic conditions and resource distribution, species can be distributed along the vertical gradient according to their ecophysiological needs. However, the network structure between distinct vertical strata remains little-explored. To fill this gap in knowledge, we used baits to sample ants in the canopy and understorey trees of a Mexican tropical rain forest to record the ant–tree co-occurrences. We examined the ant–tree co-occurrences in the canopy and understorey using complementary network metrics (i.e., specialization, interaction diversity, modularity, and nestedness). In addition, we evaluated co-occurrence patterns between ant species on trees, using C-score analysis. In general, we found no differences in the network structure, although the interaction diversity was greater in the understorey than in the canopy networks. We also observed that co-occurrence networks of each vertical stratum featured four ant species in the central core of highly co-occurring species, with three species unique to each stratum. Moreover, we found a similar trend toward ant species segregation in the both strata. These findings reveal a similar pattern of ant–ant co-occurrences in both vertical strata, probably due to the presence of arboreal-nesting ants in the understorey. Overall, we showed that despite the marked differences in species composition and environmental conditions between understorey and canopy strata, ant–tree co-occurrences in these habitats could be governed by similar mechanisms, related to dominance and resource monopolization by ants.     

The effect of different sample collection methods on rabbit blood parameters

Nowadays great deal of research is physiological field is conducted on experimental animals and there is a lot of criticism from the wide public on methods used. Therefore, recently there is a lot of effort focused on the welfare of the animals. Main aim of this study is to determine the effect of experimental sample collection method on the selected parameters of stress. In the experiment two sample collections of rabbit blood from marginal ear vein were realized – first using standard method with one person fixing the animal and other collecting the blood using gently fixating the animal. In the second groups experimental method of inserting the experimental animal into a sack and further collection in dark was realized. During the experiment the levels of cortisol – main stress indicator in organism and other health parameters of animals including mineral profile and haematological parameters were observed. Our results show no significant changes in levels of cortisol but also a decreasing tendency in the sample from the second (dark) collection. Haematological parameters were generally in the reference values and any significant changes except levels of lymphocytes and percent of lymphocytes which shown significant increase in the second collection period were found. Also the levels of mean corpuscular haemoglobin and percent of neutrophils unveiled a significant decrease in values. Values of mineral profile parameters have indicated no significant changes except the levels of phosphorus. Based on the result we can state that the experimental sample collection has no effect on blood parameters of the animals but we spectated a statistically insignificant decrease in the levels of cortisol which can suggest that the dark collection is possibly less stressful to the animals.     

Cryo-EM structure of the periplasmic tunnel of T7 DNA-ejectosome at 2.7 Å resolution

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Probing tyrosine Z oxidation in photosystem II core complex isolated from spinach by EPR at liquid helium temperatures

Tyrosine Z (Tyr_Z) oxidation observed at liquid helium temperatures provides new insights into the structure and function of Tyr_Z in active Photosystem II (PSII). However, it has not been reported in PSII core complex from higher plants. Here, we report Tyr_Z oxidation in the S₁ and S₂ states in PSII core complex from spinach for the first time. Moreover, we identified a 500 G-wide symmetric EPR signal (peak position g = 2.18, trough position g = 1.85) together with the g = 2.03 signal induced by visible light at 10 K in the S₁ state in the PSII core complex. These two signals decay with a similar rate in the dark and both disappear in the presence of 6% methanol. We tentatively assign this new feature to the hyperfine structure of the S₁Tyr_Z ^• EPR signal. Furthermore, EPR signals of the S₂ state of the Mn-cluster, the oxidation of the non-heme iron, and the S₁Tyr_Z ^• in PSII core complexes and PSII-enriched membranes from spinach are compared, which clearly indicate that both the donor and acceptor sides of the reaction center are undisturbed after the removal of LHCII. These results suggest that the new spinach PSII core complex is suitable for the electron transfer study of PSII at cryogenic temperatures.