Effect of humid tropical climate on the thermoregulatory response of Limousin × Creole and Creole growing bulls in Guadeloupe (French West Indies)

In Guadeloupe (French West Indies), eight Limousin × Creole (local) growing bulls and eight Creole bulls were either exposed to full sunshine or shaded; each climatic treatment involved half of the animals of each breed. All the bulls were fed ad libitum on a concentrate diet. Twice a week, around 12 a.m., respiratory rhythm, rectal temperature, heart rate as well as microclimatic parameters (mainly black globe temperature) were measured and a blood sample taken for packed cell volume, prolactin, and triiodothyronin (T3) plasma concentration determination. Respiratory rhythm and, to a lesser extent, rectal temperature were found to increase more for the Limousin × Creole crossbred than for the Creole bull on exposure to the sun and rise in globe temperature. However, the heart rate and blood parameters in the crossbred did not seem seriously affected by heat. This seems to indicate that the crossbred animals, though they required more positive thermal regulation than the local cattle, are not heat-stressed in the West Indian conditions. These findings are also supported by the lack of effect of exposure to the sun on the growth and carcass characteristics of such animals (reported elsewhere).     

Parathyroid hormone-related peptide (PTHrP)

PTHrP, which causes humoral malignant hypercalcaemia in man and animals, acts on bone and kidney in a way similar to that of parathyroid hormone. PTHrP released by fetal parathyroid glands stimulates placental calcium transport in pregnant ewes and maintains the calcium gradient from the dam to its foetus. PTHrP, which is also present in the mammary gland, colostrum and milk, might play an important physiological role in regulating calcium secretion through milk and calcium metabolism in newborn animals.     

Thyroliberin injected into pregnant heifers increase birthweight and stimulate postnatal growth of calves

Birthweight (51 +/- 2 kg) and mean daily weight gain (1,306 +/- 77 g; measured during the first 120 days of postnatal life) in 8 male calves born from eight primiparous heifers (mated with the same bull) given subcutaneous TRH injections (25 micrograms/kg body wt) on days 230, 240, 250 and 265 of gestation were significantly higher (+10%) than those measured in 7 control male calves born from the same bull (47 +/- 1 kg and 1147 +/- 89 g, respectively). TRH treatment also significantly increased plasma IGF1 concentrations both in term cows and in newborn calves.     

Lack of effect of metoclopramide on plasma aldosterone concentrations in young calves

In five 10-day-old Holstein X Friesian male calves, the intravenous injection of the dopamine blocker metoclopramide (1 mg/kg bwt) had no significant effect on plasma aldosterone concentration. Plasma sodium, potassium, cortisol, corticosterone concentrations and plasma renin activity measured in these animals during 120 min following metoclopramide injection were never significantly different from those simultaneously measured in 5 control calves.     

Effects of cold exposure on calcitonin secretion in the young rat

The effects of cold exposure on calcitonin (CT) secretion were evaluated in young rats. Acute cold exposure (5 h to 5 degrees C) induced a rise in plasma CT concentrations and a decrease in thyroidal CT stores without change in total and ionized plasma calcium levels. The cold activation of sympathico-adrenomedullary axis and the inhibition of CT response to cold after beta-antagonist treatment might suggest that endogenous catecholamines can enhance CT secretion in young rats. Cold adaptation (3 weeks to 5 degrees C) induced a fall in plasma calcium concentration and a rise in thyroidal CT stores without change in plasma CT levels. The high plasma glucocorticoid levels which are known to occur during chronic cold exposure could be involved in the rise of thyroidal CT content in cold adapted rats.     

An immunological study of the uncoupling protein of brown adipose tissue mitochondria

1. Ewes were injected with purified 32,000-Mr uncoupling protein from mitochondria of brown adipose tissue of cold-adapted rats in order to raise antibodies. 2. The existence of antibodies in the plasma of ewes and the cross-reactivity of plasmas were demonstrated and studied by 125I-labelled antigen-antibody reaction, double immunodiffusion, the inhibition of GDP binding to the 32,000 Mr protein and by immunohistochemistry. 3. The antibodies raised against the homogeneous protein yielded a single immunoprecipitation band with detergent-solubilized mitochondrial membranes of brown adipose tissue from rat, hamster, guinea-pig, rabbit and with the purified uncoupling protein of these animals. No immunoprecipitation was obtained with the protein purified from brown adipose tissue of term lamb foetus. 4. The GDP-binding activity of the uncoupling protein (isolated or in solubilized membranes) was largely inhibited by the antiserum. 5. The anti-(rat uncoupling protein) could not cross-react with solubilized membranes from liver or muscle, nor with the purified beef heart or rat liver ADP/ATP translocator.     

Isolation and Partial Characterization of a Staphylococcal Leukocyte Cytotaxin

A factor which attracts rabbit polymorphonuclear leukocytes both in vitro and in vivo was isolated from the culture filtrate of a strain of Staphylococcus aureus. The activity of the chemotactic factor was independent of fresh serum and it was nondialyzable. Incubation of the factor with heat-inactivated human serum markedly inhibited its chemotactic property. The factor was heat-labile (80 C, 10 min) in the crude culture filtrate but was heat-stable when partially purified.     

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.