Meriones Crassus Research Articles

Role of body temperature in seasonal acclimatization: Photoperiod‐induced rhythms and heat production in Meriones crassus

AbstractHeat production by means of nonshivering thermogenesis (NST) and food consumption were compared in individuals of the fat jird Meriones crassus, acclimated to 8L:16D and 16L:8D cycles at an ambient temperature of 28°C. Daily rhythms of body temperature were compared at the same time.A significant (P < 0.05 and P < 0.005) increase in NST and food consumption was noted in fat jirds acclimated to short photoperiod 8L:16D when compared with those acclimated to a long photoperiod 16L:8D. A clear difference in rhythms of body temperature was observed between the two groups.In light of these results it is reasonable to assume that seasonal acclimatization in the fat jird can be partly induced by the change of photoperiod. Rhythms of body temperature in the fat jird are entrained by photoperiod and appear to be adjusted to the different metabolic demands of summer and winter.

Response of the digestive tract to low quality dry food in the fat jird (Meriones crassus) and the levant vole (Microtus guentheri)

The ability to handle high and low quality diets was studied in the fat jird and levant vole. When fed a high quality diet (alfalfa hay), ‘zero time’ fermentation rates assessed by the rate of gases generated were 0·83 ± 0·20 and 0·69 ± 0·26 ml/gram caecum/h in the fat jird and levant vole respectively, and 0·96 ± 0·37 and 0·34 ± 0·14 ml/gram caecum/h respectively, when the two species were fed a low quality diet (Panicum grass). Maximal in-vitro fermentation capacity (assessed by the rate of gases generated), of the microbial population in caecal content of fat jirds and levant voles fed alfalfa hay was 2·09 ± 0·26 and 1·88 ± 0·79 ml/gram caecum/h respectively. When fed Panicum grass it amounted to 1·86 ± 0·16 and 0·89 ± 0·36 ml/gram caecum/h in the fat jirds and levant voles respectively. When fed alfalfa hay gastrointestinal tract mean retention time (MRT) was similar in both species. When fed Panicum grass MRT increased significantly by 65% in fat jirds, but was unchanged in the levant voles. Water electrolytes and volatile fatty acids (VFA) absorption along the large intestine in the levant voles maintained on the low quality diet, were reduced, but did not have a significant effect on absorption capacities of fat jirds. We suggest that the superiority of the fat jird over the levant vole in utilizing low quality feed is achieved by increasing mean retention time, maintaining fermentation rates and adequate VFA absorption.

Presence of Vesicular Bodies and Thick Basal Laminae in the Nephron of the Desert Gerbil <i>Meriones crassus</i>

Kidney samples of the adult gerbil Meriones crassus were aldehyde fixed and Epon embedded for studies of the general features of various parts of the nephrons, with particular attention to their basal laminae in all regions. Results obtained showed the presence of thick basal laminae (2-6 microns) in the parietal layer of Bowman's capsule, proximal convoluted tubule, thin loop of Henle and distal convoluted tubule. With the aid of the electron microscope, extracellular vesicular bodies were observed within the thick basal laminae in the previous regions. The bodies (50-500 nm in diameter) were found at various levels of the basal laminae. Some of them appeared to have been pinched off directly from the epithelial layer and to have moved to the underlying basal lamina, which may suggest that these vesicular bodies originated from the epithelial layer. The bodies, with a variable electron opacity, may be found either in small groups or as a single structure surrounded by a clear halo of basal lamina.

Energy metabolism and nitrogen balance in the fat jird (Meriones crassus) and the Levant vole (Microtus guentheri)

The ability of the fat jird (Meriones crassus) to survive on low quality roughages only, was studied and compared with that of the Levant vole (Microtus guentheri). The ability of the two species to balance their metabolism by lowering requirements for metabolic energy or increasing food digestibility was also studied. Energy intake of the fat jird when fed on alfalfa hay, amounted to 77% of that recorded for the levant vole, whereas energy digestibility was similar in the two species. Metabolic rate (O2 consumption) in the fat jird was 60% that of the levant vole. When fed Panicum grass, the gross and digestible energy intake and metabolic rate dropped only in the Levant vole. This drop (22%) in metabolic rate was not compatible with the decrease (52%) in digestible energy intake. In the fat jird digestible energy and O2 consumption were not significantly different from the value when fed alfalfa hay. Nitrogen metabolism was balanced on a much lower intake than in the Levant vole. The 14C-urea recycling rate was 52·7 ± 5·4% and 89·4 ± 11·6% in the fat jird and the Levant vole respectively when fed the high quality roughage. When fed the low quality roughage, urea recycling rates amounted to 67·3 ± 7.0% and 63·2 ± 6.5% respectively. When the low quality roughage was supplemented with glucose, Levant voles recycled 86·9 ± 7·8% of the urea synthesized in the liver, the same rate as when fed high quality roughage. Low energy metabolism, together with a high capacity for digesting dry plant feed and low nitrogen requirements enables the fat jird to cope with food shortage. Voles were unable to adjust to a low quality diet.

Can desert rodents better utilize low quality roughage than their non-desert kindred?

The ability of a desert rodent to exploit dry, low quality plant material and cope with shortage of adequate food, was studied in the Fat jird (Meriones crassus), a Saharo–Arabian gerbil, and compared to that in the Levant vole (Microtus guenteri). The animals were given a restricted amount of fresh carrot (20 g/day) as well as an ad libitum amount of dry roughage, of either high or low quality. Six animals of each species were used in each trial. When tested on alfalfa hay (Medicago sativa), a high quality roughage (25% fibre), the gross energy intake of the Fat jird amounted to only 43% of the value recorded in the Levant vole tested on the same diet. Apparent digestibility of this high quality roughage amounted to about 69% equally in both species. The oxygen consumption of the Fat jird, however, amounted to only 0·430 ± 0·08 litres O2/kg0·75/h, 72% of the value recorded in the vole. When tested on low quality roughage, dry Rhodes grass (Chloris gayana, 30% fibre), apparent digestibility and rate of oxygen consumption in the Fat jird were maintained at levels similar to those recorded when on alfalfa hay. In the Levant vole apparent digestibility dropped to 49% and oxygen consumption to 0·600 ± 0·12 litres O2/kg0·75/h. A high retention time of food in the gastrointestinal tract, mainly in the caecum, of the Fat jird, as well as a high rate of volatile fatty acid absorption from its in situ perfused colon, are suggested to be the major factors in lending the Fat jird its efficient digestive capacities. Both these characteristics are less pronounced in the Levant vole. It is concluded that a low rate of energy metabolism as well as a higher capacity to digest dry plant materials help the Fat jird cope with the shortage of food that is characteristic of most desert habitats.

Leishmaniasis in Israel: reservoir hosts, sandfly vectors and leishmanial strains in the Negev, Central Arava and along the Dead Sea

The reservoir animals, sandfly vectors and strains of Leishmania from foci in the southern region of Israel were studied. The rodent host species are: Psammomys obesus, Meriones crassus and probably Nesokia indica. The vector species are Phlebotomus papatasi, which were caught at all collecting sites and Ph. sergenti, which were collected in the area of the Dead Sea and in the Central Arava. Strains of Leishmania major isolated from rodents, vectors and man were serologically and enzymologically identical with regard to their excreted factor (EF) serotypes, their malate dehydrogenase (MDH), glucose-phosphate isomerase (GPI) and glucose-6-phosphate dehydrogenase (G6PDH) enzyme variant types, but exhibited three variant subtypes of 6-phosphogluconate dehydrogenase (6PGDH). The distribution of the 6PGDH subtypes correlates with three different geographical locations. Scarcity of water is the main factor limiting the biotopes of the sandflies and the spread of leishmaniasis. The subjects discussed are the dependence of sandfly distribution on rodent-burrow depth in arid areas and the inter-relationship between the leishmanial subtypes, vectors and hosts.

Helminth parasites of rodents in Kuwait with the description of a new species Abbreviata kuwaitensis (Nematoda: Physalopteridae)

Abbreviata kuwaitensis n.sp. from the stomach of Gerbillus cheesmani and Meriones crassus in Kuwait is close to A. leiperi but differs from it in the shape and size of the spicules, the position of the vulva and the size of the eggs. The larval stage of Taenia endothoracicus is reported for the first time from the body-cavity of G. cheesmani. Hymenolepis diminuta was found in the intestine of Meriones crassus for the first time.

Helminths of birds and mammals of Israel

Skrjabinocapillaria rodentium n.sp., found in the stomach of Meriones crassus, Gerbillus pyramidum, G. gerbillus, G. dasyurus and Acomys cahirinus, is described. It differs from the other two species in the genus, S. bakeri and S. eubursata, mainly in being larger, having a larger number of stichocytes and having a cephalic influation in the female and not in the male.

Cytological Events Associated with the Secretory Process in the Desert Gerbil (Meriones Crassus) Oviduct

The gerbil (Meriones Crassus) is the most abundant small mammal in Kuwait and information on reproduction of these rodents is scanty. The gerbil, M. crassus, belongs to the subfamily Gerbillinae of the family Cricetidae, Order Rodentia. Extensive light and electron microscopic studies of the oviduct of mouse, rat, rabbit, guinea pig, ruminants, and man have been reported by Nilsson and Reinius. To the best of our knowledge, no electron microscopic studies of the desert gerbil tubal epithelium during the estrous cycle have been reported. It has been shown that the secretion of the tubal epithelium is controlled by hormones and that secretion is necessary for the survival of the egg. Our knowledge of the fine structural changes which take place during secretion is incomplete. This report describes for the first time the fine structural features of the secretory process of the gerbil oviduct.

Helminths of birds and mammals of Israel. VII. - Pneumospirura rodentium n. sp. (Pneumospiruridae - Thelazioidea).

Pneumospirura rodentium a lung parasite of Gerbillus dasyurus and Meriones crassus is described. P. hainanensis Wu and Hu, 1938 and Metathelazia servalis Chabaud and Biocca, 1950, have cephalic structures resembling those of P. rodentium. But the three species can be differentiated by the size of spicules, their localization, hosts and geographical distribution.

A Slowing Down of Circadian Rhythms by Lithium Ions

Abstract Unter the permanent influence of lithium ions the circadian rhythm of movement of Kalanchoe petals is effectively lengthened but a pulse administered up to 12 hours has no influence. Lithium ions could also be demonstrated to similarly slow down the circadian activity rhythm of a small mammal (Meriones crassus). It is hypothesized that the therapeutic effect of lithium salts in endogenous depressions in human beings may result also from its acting on the human circadian system

Comparative ultrastructural-morphometric studies on parenchymatic liver cells in Wistar rats (Rattus norwegicus) and desert rats (Meriones crassus) after a single dose of clofibrate

Male Wistar (rattus norvegicus) and desert rats (meriones crassus) were given a single dose of 200 mg/kg of clofibrate (CPIB) p.o. and liver tissue was analysed by ultrastructural morphometry. CPIB induced a biphasic reaction pattern of hepatocellular organelles both in Wistar and desert rats. In the initial phase (2–5 h) the volume share of mitochondria per hepatocyte increased in both strains. In the hepatocytes of desert rats the total number of mitochondria increased whereas the volume of the single mitochondrium remained constant. In contrast, in Wistar rats the volume of the single mitochondrium showed a threefold increase. In the initial phase the number of microbodies both in Wistar and desert rats decreased, but the single volume doubled.

Effect of acute dehydration on body fluid compartments in three rodent species, Rattus norvegicus, Acomys cahirinus and Meriones crassus

1. 1. After acute dehydration Rattus norvegicus, Acomys cahirinus and Meriones crassus lost 18·6, 12·8 and 7 per cent of their body weight. The decrease in body water (g/100 g animal) was 21·0, 11·2 and 3·3 (mean figures). 2. 2. The relative changes in plasma volume due to dehydration were 34, 4·9 and 11 per cent respectively. Extracellular fluid volume decreased by 32, 0 and 18 per cent. 3. 3. T-1824 half-life in the blood system decreased during dehydration in R. norvegicus and M. crassus. In A. cahirinus T 1 2 increased. 4. 4. Sources of water loss during dehydration and possibility of capillary permeability changes are discussed.

The Fleas (Siphonaptera) of Egypt. New Records

A new subspecies of the dormouse flea, Myoxopsylla laverani (Roths., 1911), is described from Northern Egypt and recent collections of Echidnophaga murina (Tiraboschi, 1903) from gerbilline rodents in Egypt are recorded. The works of Hoogstraal and Traub (1963a, 1963b, 1965a, 1965b, 1966), Traub (1954, 1963a, 1963b), and Traub and Hoogstraal (1957) form the most comprehensive report of the flea fauna of any country in the Middle East. They treat the fleas collected in Egypt by the United States Naval Medical Research Unit Number Three during the past 16 years. Few flea species are likely to be added to the current list of those known from Egypt. In the present paper, however, data for one recently collected species, previously unrecorded by Hoogstraal's group, are included as well as the description of a new subspecies that was previously inadequately known for descriptive purposes. The following is a brief report on their occurrence. Echidnophaga murina (Tiraboschi, 1903) The single record of this species in Egypt is that of one female from Rattus rattus alexandrinus collected at Kom Ombo in November 1911 (Hopkins and Rothschild, 1953). During routine identification of material collected by NAMRU 3, a large series of specimens taken from Meriones crassus ssp. and Jaculus o. orientalis from the Matruh and Red Sea Governorates proved to be this species. Although there are certain minor irregularities in the contours of the male genitalia, Traub (pers. comm.) states that they are identical with specimens of E. murina from Libya in his collection. Both Meriones crassus and Jaculus orientalis appear to be atypical hosts for this flea which Received for publication 22 June 1966. * From Research Project MR005.09-1402.5, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the author and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. has previously usually been associated only with murine rodents. Although fleas of this species normally occur in limited numbers on an individual host, those in these collections were taken in considerable numbers, as the following records from Egypt show.