A comparative study of hepatic and epidermal histidase in the guinea-pig (Cavia porcellus)

Histidine ammonia lyase was purified to homogeneity from guinea-pig liver and epidermis. Both enzymes had similar molecular weights, subunit composition and pH optima. Km values for the two were similar at pH 9.2 but different at pH 7.0. Both enzymes were stimulated by low thiol concentrations and inhibited at higher concentrations, but to different extents. Antibody to the hepatic enzyme showed complete identity against hepatic enzyme but incomplete identity against epidermal enzyme.     

Skull growth in the albino rat (Rattus norvegicus)

A longitudinal study of growth in the rat skull, based on serial radiographs, has shown that by the age of one month after birth, the braincase attains some 93% of its adult (fifth-month) size whilst the facial skeleton and mandible attain but 75% of their adult size. By the third month, growth in the braincase has virtually ceased, whereas significant facial growth continues until the age of five months.     

Control of the estrous cycle in guinea-pig (Cavia porcellus)

The aim of this work was to look for a simple method to obtain synchronized ovulation in guinea pigs under farming conditions while respecting animal welfare. The luteolytic activity of three different prostaglandins F2alpha (PGF2α) analogs (D-cloprostenol, D,L-cloprostenol and luprostiol) and a daily treatment with oral progestagen (altrenogest) was tested successively at different stages of the estrous cycle on the same group of females during a period of 8 mo. The estrous cycle length was not modified by the administration of PGF2α analogs, whatever the stage of the estrous cycle when the treatment was initiated. Our results led us to reject the use of PGF2α analog to induce practical synchronization of the estrus in this species. In females (n = 29), given 15 days with altrenogest (0.1 mL po once a day), ovulation occurred 4.43 ± 0.13 days after the end of the treatment. Altrenogest treatment was followed by mating. No negative impacts of the treatment on the pregnancy rates, delivery rates and litter sizes were observed. This standard method of guinea-pig estrus synchronization is less stressful for the animals compared to techniques using progesterone tubing.     

Effects of animal or plant protein diets on cecal fermentation in guinea pigs (Cavia porcellus), rats (Rattus norvegicus) and chicks (Gallus gallus domesticus)

Monogastric herbivores such as the guinea pig depend on energy supply from enteric fermentation as short-chain fatty acids (SCFA) corresponding to 30-40% of their maintenance energy requirements. They evolved specific digestive system to adapt their indigenous microflora to plant polysaccharides fermentation. No information has been available about the adaptability of microbial fermentation in hindgut of the monogastric herbivorous to an animal protein diet. We investigated if the guinea pig can fully retrieve energy of an animal protein diet by hindgut fermentation compared with a plant protein diet. For comparison, we also studied two omnivores. End products of in vitro cecal fermentation (SCFA, ammonia and gases) were measured to judge how well an animal protein diet could be fermented. The animal protein diet resulted in the less intensive fermentation with increased feed intake and volume of cecal contents than the plant protein diet only in guinea pigs. This may be due to a limited capacity of the hindgut microflora to adapt to the substrate rich in animal protein. We also found that chick cecal contents produced methane at higher emission rate than ruminants.     

The colonic separation mechanism in the guinea-pig (Cavia porcellus) and the chinchilla (Chinchilla laniger)

In guinea-pig, the concentration of nitrogen and viable bacteria were nearly twice as high in the contents of the colonic furrow compared to the contents of the corresponding lumen. Labelled bacteria infused into the proximal colon of guinea-pigs were transported in the furrow into the caecum. Both species produced two types of pellets, one nitrogen-rich intended for caecotrophy, and one nitrogen-poor delivered as faecal pellets. The furrow is part of a separation mechanism in both species saving bacteria for the animals.     

Idiopathic megaesophagus in a rat (Rattus norvegicus)

Necropsy and histopathologic examination of a rat (Rattus norvegicus) revealed megaesophagus and gangrenous bronchopneumonia. The esophageal dilitation, mural atrophy with persistence of neural structures, regurgitation and bronchopneumonia seen in this case were similar to findings in other animals with megaesophagus.     

Polymorphic microsatellite loci of the rat (Rattus norvegicus)

The EMBL and GenBank DNA databases were searched for microsatellite sequences of the rat containing dinucleotide repeats of (CA)_n and (GA)_n. Among those obtained, 23 sequences were analyzed by polymerase chain reaction to examine the size variation of the amplified fragment in inbred rat strains. All of the 23 microsatellite sequences varied in size among the strains tested. The 23 microsatellite loci in a pair of substrains separated from the same progenitor strain were then analyzed. Fragments identical in size were observed in all loci of the two substrains, indicating the stability of the microsatellite over a large number of generations. The microsatellite loci, therefore, should be useful markers for linkage analyses in the rat.     

Circadian and seasonal variations of some metabolic parameters in the serum of the albino laboratory rat (Rattus norvegicus var. alba).

Total protein (TP), glucose (GL), esterified fatty acids (EFA) and total cholesterol (TC) were determined at 4-hour intervals during the 24-hour cycle in the serum of 270 female Wistar rats, in February, May and July. The results can be summed up under the following points: 1) The differences found between the levels of the given parameters in February, May and July were statistically highly significant. The greatest differences were observed in the TC level, which was lowest in July (0.82 mmol/l) and highest in February (1.87 mmol/l). The highest TP and GL values were found in May (62.5 g/l; 10.69 mmol/l) and the lowest in February (40.1 g/l; 7.8 mmol/l). The smallest differences were observed in the EFA level, which was highest in July (8.09 mEq/l) and lowest in February (6.39 mEq/l). The minimum 24-hour variations in the levels of most of the given parameters during the 24-hour cycle were observed in May (compared with February and July). 2) In a study of TP and GL concentration, the time of day was found to be a very important factor. The maximum TP level during the 24-hour cycle was found most often in the early morning or forenoon, while the blood glucose level was highest at about midday and in some cases in the early morning. The blood cholesterol level was relatively stable during the 24-hour cycle and it is impossible to draw definite conclusions from its fluctuations. Changes in the EFA level during the 24-hour cycle were likewise irregular. 3) Except for cholesterol, interindividual differences in the levels of the given parameters in the various months seem to be statistically non-significant.     

Blood coagulation studies in guineapigs (Cavia porcellus)

Blood coagulation studies were performed on 45 healthy, adult guinea pigs. Additionally thrombelastograms of 30 animals were recorded. Guineapigs revealed short partial thromboplastin times and euglobulin lysis times, but long prothrombin times and thrombin times. Fibrinogen values were within the range of human normal values. Biphasic ADP-induced aggregation of platelets, as occurs in man, was found in 29% of the animals. Short r (reaction time until the beginning of clot formation) and k times (time from the beginning of clot formation until an amplitude of 20 mm) of their thrombelastograms indicate, that whole blood clotting is enhanced in guineapigs. Higher maximum amplitudes in this species suggest a stronger clot stability than in man.     

Effect of dietary protein on zinc phosphide toxicity in albino rats (Rattus norvegicus)

Adult male and female albino rats (R. norvegicus) were administered rodenticide, zinc phosphide ranging from 4, 2, 1, 0.5, 0.25 and 0.125% in the diet containing 10(A), 17(B) and 24%(C) protein. Zinc phosphide induced 100% mortality at 4, 2, 1, 0.5% in diet A; 4 and 2% in diet B; and 4% in diet C. The results reveal influence of dietary protein in modulating the toxicity of zinc phosphide, suggesting that greater caution should be exercised while formulating its baits for effectiveness. The results also suggest that baits having 10% protein are more suitable to carry the rodenticide from view point of acceptability and efficacy towards the target species.