Influences of Follicular Size on Parthenogenetic Activation and in Vitro Heat Shock on the Cytoskeleton in Cattle Oocytes

The availability of cow ovaries from the slaughterhouse has been very limited in Taiwan. To maximize the use of cow ovaries for research purposes, whole ovary dissection was performed and the developmental competence of the oocytes derived from different sizes of follicles was assessed by the rates of in vitro maturation (IVM) and parthenogenetic activation of the oocytes in Experiment 1 (Exp 1). Cumulus-oocyte complexes (COCs) derived from small (1-2 mm) and large (3-8 mm) follicles were subjected to standard IVM culture for 24 h. Mature oocytes were selected and then parthenogenetically activated using A23187 (5 microm, 5 min) or thimerosal (200 microm, 10 min) alone or combined with 6-dimethylaminopurine (2.5 mm and 3.5 h, respectively). Activation rates of the oocytes, neither from the large nor small follicles, were affected by different activation treatments (single or combined stimuli). Whereas maturation rates for the oocytes from large follicles were superior to those from small follicles in both the single (59% vs 45%) and combined treatments (76% vs 40%; p < 0.05). To understand how prolonged heat shock (HS) influences cytoskeletal configurations of mature bovine oocytes, in Experiment 2 (Exp 2), matured oocytes derived from large follicles were randomly allocated to different durations of HS treatments at 41.5 degrees C for 0 (C0h, control, n = 12), 1 (HS1h, n = 28), 2 (HS2h, n = 31), and 4 h (HS4h, n = 30). An additional control group was cultured for 4 h without HS (38.5 degrees C, 4 h, n = 35). Alterations in nuclear structures, microtubules (MTs), and microfilaments (MFs) of the oocytes were examined. Abnormalities in the chromosomes, spindle MTs and the percentages of oocytes with cytoplasmic MTs increased with time of HS treatment. The intensity of the MF distribution in the HS oocytes was also altered. Significant changes in the cytoskeleton after HS may be associated with the reduced development under hyperthermia and, perhaps, with the low pregnancy rates of the animals during hot seasons.     

Efficacy of tilmicosin in the control of experimentally induced Actinobacillus pleuropneumoniae infection in swine

The efficacy of tilmicosin administered in the feed to control Actinobacillus pleuropneumoniae infections in pigs was evaluated through a multisite, multitrial study. For each of 6 trials, 48 pigs (stratified by weight and sex) were randomly assigned to 6 to 8 pens. Medicated feed containing tilmicosin (200 g/t) and unmedicated feed were randomly assigned at the pen level and were provided ad libitum from day −7 to trial termination (day 14). Seeder pigs (inoculated intranasally with A. pleuropneumoniae serotype 1 and showing signs of clinical disease) were introduced to each pen on day 0. Rates of death, gross lesions, and culture of A. pleuropneumoniae at necropsy, clinical scores, average daily gain in weight, and average body temperature were compared between the medicated and unmedicated pigs. Compared with the unmedicated pigs, significantly fewer (P < 0.05) pigs given tilmicosin had lesions typical of A. pleuropneumoniae or had A. pleuropneumoniae isolated from their tissues at necropsy. Together with a significant reduction (P < 0.05) in the average percentage of pneumonic lung involvement (both visually and by weight), there were reductions in the numbers of pigs with moderate and severe pneumonic lung lesions and with A. pleuropneumoniae associated mortality. With tilmicosin treatment, the average daily weight gain, daily temperature, abdominal appearance, attitude, and respiration were also significantly better (P < 0.05). The results of this study demonstrate the in vivo effectiveness of tilmicosin (200 g/t) in controlling pleuropneumonia among swine experimentally infected with A. pleuropneumoniae.     

Exploring passive transfer in muskoxen (Ovibos moschatus).

Poor calf production and ill thrift in 3-4 mo olds are common limiting problems in raising and maintaining captive muskoxen (Ovibos moschatus). Acute onset of a rapidly progressing enteritis and septicemia in neonatal calves (2-7 days of age) caused by Escherichia coli not normally considered pathogenic in domestic animals is a serious problem in many captive muskoxen facilities. Serum immunoglobulin G (IgG) levels, total protein, albumin, and globulin levels in captive periparturient muskox females and their neonatal calves were compared with levels found in other species in which these parameters have been well described. Results showed that all females in the study had IgG present in their serum (mean = 1,232.14 mg/dl, SD = 178.34 mg/dl, as measured via radial immunodiffusion). Calves were probably born agammaglobulinemic or hypogammaglobulinemic. IgG levels quickly rose in calves after initial colostrum intake to levels similar to those seen in other domestic ruminants. Our results suggest that passive transfer of immunity in muskoxen is similar to what is reported in domestic livestock and that reference ranges from domestic cattle may be used to assist interpretation of serum IgG levels in muskoxen. In addition, the positive relationship between serum protein and globulin levels with serum IgG levels is similar to that reported for Holstein cattle and thus provides a useful indicator of passive transfer in muskoxen.     

Successful Low Dose Insemination of Flow Cytometrically Sorted Ram Spermatozoa in Sheep

The fertility of ram spermatozoa that had undergone flow cytometric sorting (MoFlo SX) and cryopreservation was assessed after low-dose insemination of synchronized Merino ewes. Oestrus was synchronized with progestagen-impregnated pessaries, PMSG and GnRH treatment. Ewes (n = 360) were inseminated with 1 x 10(6), 5 x 10(6) or 15 x 10(6) motile sorted frozen-thawed (S(1), S(5), or S(15) respectively) or non-sorted frozen-thawed (C(1), C(5) or C(15) respectively) spermatozoa from three rams. An additional group of ewes were inseminated with 50 x 10(6) motile non-sorted frozen-thawed spermatozoa (C(50)) to provide a commercial dose control. The percentage of ewes lambing after insemination was similar for C(50) (24/38, 63.2%), C(15) (37/54, 68.5%), S(15) (38/57, 66.7%), S(5) (37/56, 66.1%) and S(1) (32/52, 61.5%) groups (p > 0.05), but lower for C(5) (19/48, 39.6%) and C(1) (19/55, 34.5%) treatments (p < 0.05). This study demonstrates sorted ram spermatozoa are equally fertile to non-sorted spermatozoa even when inseminated at 2% of the dose. Furthermore, at very low artificial insemination doses (1 or 5 million motile) the fertility of sorted ram spermatozoa is superior to non-sorted spermatozoa inseminated in equal numbers. These results have significance for the future commercialization of sex-preselection technology in sheep as a reduction in the minimum effective sperm number will allow a corresponding decrease in the associated cost per dose.     

The ability of a yeast-derived cell wall preparation to minimize the toxic effects of high-ergot alkaloid tall fescue straw in beef cattle

Two experiments were conducted to evaluate the influence of a yeast-derived cell wall preparation (YCW) on forage intake and digestibility, ruminal fermentation characteristics, serum prolactin and prolactin stores, and milk production in beef cattle consuming high-alkaloid tall fescue straw. In Exp. 1, 16 ruminally cannulated Angus x Hereford steers (200 +/- 6 kg of BW) were blocked by BW and within block were assigned to 1 of 4 treatments containing YCW at 0, 20, 40, or 60 g/d. Tall fescue straw (579 mug of ergovaline/ kg of DM) was provided at 120% of the previous 5-d average intake, with soybean meal used as a CP supplement. In the 29-d digestion study, total DM, OM, and NDF intakes and DM, OM, and NDF digestibilities were not affected by YCW supplementation (P > 0.13). Linear decreases in ruminal indigestible ADF outflow (P = 0.10) and liquid dilution rate (P = 0.03) were noted as YCW increased. Weekly serum prolactin was not affected by treatment (P > 0.50), but prolactin stores increased linearly as YCW increased (P = 0.05). In Exp. 2, 60 Angus x Hereford cows (517 +/- 5 kg of BW; approximately 200 d of gestation) were stratified by BCS (5.0 +/- 0.1) and randomly assigned to the same 4 YCW treatments as in Exp. 1 (447 microg of ergovaline/kg of DM, high-alkaloid straw), but with the addition of a low-alkaloid straw (149 microg of ergovaline/kg of DM; no YCW supplementation) as a control. Cows were provided ad libitum access to straw, and diets were supplemented with soybean meal daily. One cow was removed from the 40 g/d treatment because of clinical signs of fescue foot. No differences (P > 0.20) were observed in pre-or postcalving BCS change or postcalving BW change. Control cows gained more BW (P = 0.02) precalving compared with cows given 0 g/d of YCW. A linear increase (P = 0.04) in milk production at 60 d postpartum was observed as YCW increased. Serum prolactin post-calving and the change from initial to postcalving increased linearly (P = 0.02 and P = 0.06, respectively) with increasing YCW supplementation. In addition, postcalving serum prolactin was less for 0 g/d of YCW compared with the control (P = 0.003) and 20 g/d of YCW (P = 0.04). The YCW seemed to alleviate the prolactin depression normally associated with fescue toxicosis and therefore has the potential to be used successfully with other management practices when feeding or grazing high-alkaloid tall fescue.     

Blood smear from a pregnant cat that died shortly after partial abortion

A 1-year-old, 5- to 6-week pregnant cat was presented with a history of aborting 3 kittens the previous night. During the examination, the cat began to seizure and died. At necropsy, formalin-fixed tissues and blood smears prepared from an EDTA blood sample collected via cardiac puncture were submitted to a diagnostic laboratory. Examination of the blood smears revealed numerous large (15-75 microm) clumped macrophages containing dark blue intracytoplasmic organisms consistent with Cytauxzoon merozoites. Scattered erythrophagocytic macrophages were also observed. Within several erythrocytes, 1-2 small, round, ring-like piroplasms consistent with Cytauxzoon were observed. Histologic examination revealed numerous large, schizont-laden macrophages filling the blood vessels of multiple organs. The cytologic and histologic findings were diagnostic for Cytaxuzoon felis infection. This case was of particular interest because of the unusually large number of organism-laden macrophages in the cardiac blood sample, an uncommon finding in peripheral blood. Although the cat was presented for complications of abortion, it remains uncertain whether C felis organisms crossed the placenta and infected the fetuses or lead to the abortions.     

Long-term,landscape patterns of past fire events in a montane ponderosa pine forest of central Colorado

Parameters of fire regimes, including fire frequency, spatial extent of burned areas, fire severity, and season of fire occurrence, influence vegetation patterns over multiple scales. In this study, centuries-long patterns of fire events in a montane ponderosa pine – Douglas-fir forest landscape surrounding Cheesman Lake in central Colorado were reconstructed from fire-scarred trees and inferences from forest stand ages. We crossdated 153 fire-scarred trees from an approximately 4000 ha study area that recorded 77 total fire years from 1197 to the present. Spatial extent of burned areas during fire years varied from the scale of single trees or small clusters of trees to fires that burned across the entire landscape. Intervals between fire years varied from 1 to 29 years across the entire landscape to 3 to 58 years in one stand, to over 100 years in other stands. Large portions of the landscape did not record any fire for a 128 year-long period from 1723 to 1851. Fire severity varied from low-intensity surface fires to large-scale, stand-destroying fires, especially during the 1851 fire year but also possibly during other years. Fires occurred throughout tree growing seasons and both before and after growing seasons. These results suggest that the fire regime has varied considerably across the study area during the past several centuries. Since fires influence plant establishment and mortality on the landscape, these results further suggest that vegetation patterns changed at multiple scales during this period. The fire history from Cheesman Lake documents a greater range in fire behavior in ponderosa pine forests than generally has been found in previous studies.     

Femtosecond Dynamics of Excited-State Evolution in

Time-resolved absorption spectroscopy on the femtosecond time scale has been used to monitor the earliest events associated with excited-state relaxation in tris-(2,2'-bipyridine)ruthenium(II). The data reveal dynamics associated with the temporal evolution of the Franck-Condon state to the lowest energy excited state of this molecule. The process is essentially complete in approximately 300 femtoseconds after the initial excitation. This result is discussed with regard to reformulating long-held notions about excited-state relaxation, as well as its implication for the importance of non-equilibrium excited-state processes in understanding and designing molecular-based electron transfer, artificial photosynthetic, and photovoltaic assemblies in which compounds of this class are currently playing a key role.     

Lecithin aerosols generated ultrasonically above 25 degrees C

Dl-Dipalmitoyl-alpha-lecithin, suspended in 0.15-molar sodium chloride solution by sonic cavitation at 20 kilohertz, can be aerosolized by an 800-kilohertz ultrasonic generator only at temperatures above 25 degrees C. The aerosol thus produced is exceptionally stable against evaporation even at particle radii of 0.1 to 0.6 micron; this suggests applicability to the therapy of pulmonary disorders.