Adenohypophyseal receptors for LHRH, pituitary content of gonadotropins and plasma concentrations of LH in cyclic, pregnant and postpartum beef cows

Adenohypophyseal concentrations of LHRH receptors, pituitary content of LH and FSH, and plasma concentrations of LH were determined in thirty Hereford, Angus or Hereford-Angus heifers that were randomly assigned by breed and weight to five periods including day 3 of the estrous cycle (CY), pregnant day 120 (P120), 200 (P200), 275 (P275), or day 2 postpartum (PP). Jugular blood samples were collected at 10-min intervals for 8 hr from all cows. Within 2 hr after completion of blood sampling, animals were slaughtered and the pituitary gland frozen at −196 C. LH pulse frequency/8 hr was reduced (P<.05) during gestation (.5, .2, and 1.5 ± .5/8 hr, for P120, P200, and P275, respectively) and PP (.5 ± .5/8 hr) compared to CY (7.8 ± .5/8 hr). Frequency of LH pulses/8 hr was not different (P>.1) among P120, P200 or PP periods but was different (P<.05) between P200 and P275. There were no differences in LH pulse height (P>.1) among periods; however, pulse amplitude was greatest (P<.05) at P120 (1.3 ± .2 ng/ml) and lowest between P200 and PP (.6 to .8 ± .2 ng/ml). Baseline concentrations of plasma LH did not differ (P>.1) among P and PP periods (.3 ± .1 ng/ml), but were lower (P<.05) than in CY animals (.7 ± .1 ng/ml). Concentration of adenohypophyseal LHRH receptors was approximately two-fold greater (P<.05) at P120 (25.85 ± 2.2 fmol/mg) than at all other periods (9.5 to 14.9 ± 2.2 fmol/mg). Pituitary content of LH was greatest at P120 (1.56 ± .11 ug/mg) and lowest (P<.05) at P275 and PP (0.46 to 0.52 ± .11 ug/mg). Pituitary content of FSH was greatest (P<.05) in P (12.7 to 17.0 ± 1.4 ug/mg) and PP (18.3 ± 1.4 ug/mg) vs CY (5.0 ± 1.4 ug/mg) cows and increased from P120 to PP (P<.05). Results indicate that physiological changes occurring during gestation may have an effect on subsequent function of the adenohypophysis in beef cows.     

Arboviruses recovered from sentinel livestock in northern Australia

Over 700 arboviruses were recovered between 1981 and 1987 from the blood of sentinel livestock near Darwin. Twenty-three isolates were made from sheep, goats, swamp buffalo (Bubalus bubalis) and horses, and the remainder were from cattle. The isolates have been typed as 27 separate viruses belonging to the bluetongue, epizootic haemorrhagic disease, Palyam, Simbu, bovine ephemeral fever, Tibrogargan and alphavirus groups. Ten of these viruses have not been isolated elsewhere in Australia and four have been isolated only in Darwin. Considerable annual variations in virus activity and in the durations of detectable viraemia were observed.     

Isolation of Mycoplasma salivarium from swine

Mycoplasma salivarium, a common human oropharyngeal mycoplasma, was isolated from nasal and pharyngeal secretions of 14 of 284 swine in a barrier-maintained, disease-free herd. M. salivarium was recovered from one boar 6 times over a 26-month period and one time only from 13 other swine. Human isolates of M. salivarium were compared with the swine isolates by DNA-DNA hybridization and SDS-PAGE of the cell proteins and the strains were shown to be closely related. One of eight of the swine from which M. salivarium was isolated had complement-fixing antibodies and another culture-positive animal had metabolic-inhibiting antibodies to M. salivarium. Overt disease was not associated with the organism. These results support previous findings that mycoplasmas closely related to M. salivarium may be isolated from the nasopharynges of swine and they further indicate that the organism can establish persistently in swine without evidence of overt disease.     

Clinical and subclinical colloid goitre in adult camels (Camelus dromedarius) at Kordofan region of Sudan

Colloid goitre was diagnosed in adult camels in the Kordofan region of the Sudan. The disease is characterized by gross enlargement of the thyroid, histopathological follicular changes, reproductive disorders, low concentrations of circulating thyroid hormones (T3, T4) and normocytic normochromic anaemia. The possible cause of the condition is discussed and iodine supplementation is recommended.     

Observations on the treatment of necrobacillosis in wallabies

Clinical experience of 73 cases of necrobacillosis in red-necked wallabies (Macropus rufogriseus) over a 6-year period is reviewed. Diagnostic methods and the medical and surgical treatment options are detailed. It is suggested that survival curves are necessary to assess the outcome of treatment.     

Equine metacarpophalangeal joint surface contact changes during walk, trot and gallop

Changes in the staining pattern for the metacarpophalangealjoint in the walking, trotting and galloping positions were studied. For this purpose, horse limbs from the third metacarpal bone distally were harvested and placed in the mid-stance position on a hydraulic press that applied the load required to obtain the palmar fetlock angles corresponding to the walking (218 degrees), trotting (226 degrees) and galloping positions (240 degrees), and a 1:1000 diluted aqueous dilution of methylene blue was injected into the fetlock joint.Based on the results, increasing the palmar fetlockangle in the anatomical specimen caused the contact zones of the proximal phalanx and the proximal sesamoidean bones with the third metacarpal bone joint surface to shift dorsally, thereby increasing the contact surface area between the involved bones.In the galloping position, the proximal phalanx wasfound to extend beyond the dorsal boundary of the third metacarpal bone joint surface and its basal portion to depart from the metacarpus in such a way that the distal sesamoidean ligaments forced the basilar zone of the proximal sesamoidean bones to separate.These phenomena may obviously assist in explaining the intricate biomechanics of the joint as well as its associated pathologies.     

Oxytocin synthesis and secretion from bovine corpora lutea exposed in vitro to cycloheximide and colchicine

Two experiments were conducted to study the effects of cycloheximide and colchicine on prostaglandin F₂ (PGF₂)-induced secretion and synthesis of oxytocin in bovine luteal tissue in vitro. Corpora lutea were collected from beef heifers on Day 8 of the estrous cycle. In Experiment 1, incorporation of [¹⁴C]-leucine into oxytocin synthesized and secreted by luteal slices after exposure to PGF₂, cycloheximide and cycloheximide plus PGF₂ was examined. In Experiment 2, synthesis and secretion of oxytocin were evaluated in luteal slices incubated with colchicine and PGF₂ alone and in combination. Cycloheximide inhibited incorporation of labeled leucine into luteal proteins by more than 90% and no labeled oxytocin was detected in the media or tissue. Prostaglandin F₂ induced significant secretion of oxytocin that was not inhibited by cycloheximide. Tissue levels of oxytocin after incubation with cycloheximide and/or PGF₂ did not differ and were similar to those of the incubated control. Colchicine alone did not suppress oxytocin secretion and did not alter the ability of PGF₂ to induce significant secretion of this nonapeptide. Tissue concentrations of oxytocin after incubation with colchicine and/or PGF₂ did not differ. These studies indicate that secretion and replenishment of luteal oxytocin in vitro is not contingent upon de novo protein synthesis. Inability of colchicine to suppress oxytocin secretion and synthesis may have been due to the short duration of exposure of luteal tissue to the drug.     

A method for the analysis of the δ18O of inorganic phosphate extracted from soils with HCl

The oxygen isotope composition of phosphate (δ¹⁸O‐PO₄) has successfully been used to study the biological cycling of phosphorus (P) in seawater and marine sediments. However, only a few studies have used this approach in soils. In order to analyse δ¹⁸O‐PO₄, phosphate must be extracted from the soil, purified and converted to silver phosphate (Ag₃PO₄). The published extraction methods, successfully applied to marine waters and sediments, lead to the precipitation of impure Ag₃PO₄when used with soils or organic‐rich samples. Here we present an improved purification protocol, designed for soils and other organic‐rich samples. After extraction with HCl, phosphate is purified with multiple mineral precipitations that do not require extreme pH adjustments of the solutions. We show that contaminant‐free Ag₃PO₄ can be produced from fertilizers and various soils with different chemical and physical characteristics. Our first isotopic results confirm that differences in P status and availability in soils are expressed in the δ¹⁸O‐PO₄ signal, indicating the potential of this isotopic tracer to understand P dynamics in soil systems.     

A Multivariate Hidden Markov Model for the Identification of Sea Regimes from Incomplete Skewed and Circular Time Series

The identification of sea regimes from environmental multivariate times series is complicated by the mixed linear?Ccircular support of the data, by the occurrence of missing values, by the skewness of some variables, and by the temporal autocorrelation of the measurements. We address these issues simultaneously by a hidden Markov approach, and segment the data into pairs of toroidal and skew-elliptical clusters by means of the inferred sequence of latent states. Toroidal clusters are defined by a class of bivariate von Mises densities, while skew-elliptical clusters are defined by mixed linear models with positive random effects. The core of the classification procedure is an EM algorithm accounting for missing measurements, unknown cluster membership, and random effects as different sources of incomplete information. Moreover, standard simulation routines allow for the efficient computation of bootstrap standard errors. The proposed procedure is illustrated for a multivariate marine time series, and identifies a number of wintertime regimes in the Adriatic Sea.