The haemoglobins of Labeo umbratus (Smith) and Labeo capensis (Smith)

The haemoglobins of both L. umbratus and L. capensis separated into four components on polyacrylamide electrophoresis. The isoelectric points of these fractions were found to be 9.35, 6.89, 6.63 and 6.40. Organic nucleotide triphosphate concentration in the blood of L. capensis was found to be 56.72 ± 18.01 mg% and 58.72 ± 17.9 mg% in the case of L. umbratus . It is not possible to distinguish between L. umbratus and L. capensis purely on the basis of the haemoglobin electropherogram.     

The plasma proteins of Labeo umbratus (Smith) and Labeo capensis (Smith)

The plasma proteins of L. umbratus and L. capensis have been investigated by means of cellulose-acetate and polyacrylamide gel electrophoresis. Characteristic patterns were obtained for each specie although variations occur within a certain basic framework. Certain fractions were further isolated and approximate average molecular weights were found to vary between 55 000 and above 120 000 and isoelectric points between 5.78 and 4.2. Certain fractions were found to exist in dimeric form. It is concluded that the application of the human nomenclature to fish plasma protein fractions is of dubious value and that the fish fractions can only be classified after thorough biochemical investigation.     

Surface area of the respiratory organs of the Climbing perch, Anabas testudineus (Pisces: Anabantidae)

Measurements have been made of the surface area of the gills and accessory respiratory organs of Anabas in the weight range 1–120 g, and the data analysed with respect to body weight using logarithmic transformations. The slope of the regression line for total gill area (0–615) is less than that found in most fish, the number of secondary lamellae/mm decreased more rapidly with body weight than for most water-breathing species (h = -0.152). The gill area of Anabas is relatively small but when the area of the accessory organs is added, the total respiratory area is of the same order as inactive water-breathing fish. The regression coefficient for combined areas of labyrinthine organs and lining of the suprabranchial chambers (0.713) exceeds that for the gills and together with other evidence (including estimates of diffusing capacity from morphological measurements), indicates an increasing importance of air-breathing of larger specimens. The average surface area of the accessory organs available for 1 ml of air within the suprabranchial chambers was found to be 2226 mm².     

Electrophoresis of haemoglobin in single erythrocytes of Labeo umbratus (Smith) and Labeo capensis (Smith)

Electrophoresis of haemoglobin in single erythrocytes of Labeo umbratus and Labeo capensis showed that haemoglobin behaved in three distinct ways in both species. The majority of cells contained haemoglobin which moved as a broad band towards the anode. In a few cells haemoglobin moved towards both the anode and the cathode and in even fewer cells, haemoglobin moved as a sharp band to either the cathode or anode. These results are discussed in relation to other observations.     

Pathophysiology of hemorrhagic shock. A model for studying the effects of acute blood loss in the rat

A model of acute blood loss in rats with a reproducible mortality rate over a wide range of body weights was developed by withdrawing various amounts of fixed blood volume per 100 g body weight via the left common carotid artery and observing the survival of the animals. Younger (lighter) animals survived the bleeding longer than older (heavier) animals. As early as 70 min following the shock episode there was evidence of acute tubular necrosis in kidney proximal tubules and focal centrilobular necrosis in the liver. The 84%, 50%, or 16% body weight - mortality line was: V84 = -0.17 BW + 3.25; V50 = -0.18 BW + 3.16; or V16 = -0.18 BW + 3.01 in animals ranging from 250 to 400 g body weight (where V = bleeding volume ml/100 g body weight, BW = body weight in grams X 10(-2). To produce the same mortality rate, the bleeding volume per unit body weight decreased with increased body weight. On the other hand, the bleeding volume per total blood volume or per unit body surface area increased with increased body weight. The body weight-mortality line is a useful method to calculate the bleeding volume to produce predetermined mortality rate. This method can be easily applied to various pathophysiological and metabolic studies on the nature of acute blood loss as well as in the treatment of acute blood loss.     

Sexual dimorphism, reproductive biology, and food habits of two species of African filesnakes (Mehelya, Colubridae)

The ecology and general biology of African snakes remains virtually unstudied, even in highly distinctive species such as the filesnakes (genera Mehelya and Gonionotophis ). Our measurements and dissections of preserved specimens provided information on body sizes, sexual dimorphism in size and bodily proportions, clutch sizes, and food habits of two Mehelya species. In both M. capensis and M. nyassae , females attain sexual maturity at the same size as conspecific males, but grow to much larger sizes. Mehelya capensis displays extreme differences in body shape between males and females at the same body length: females have longer and wider heads, thicker bodies, and larger eyes (relative to both head length and head width) than do conspecific males. Dimorphism in body proportions is less marked in M. nyassae. Female reproductive cycles are seasonal in M. capensis , and clutch sizes are larger in this species than in its smaller congener (5-11 eggs in M. capensis , 2-6 eggs in M. nyassae ).
Contrary to popular wisdom, Mehelya are not specialized ophiophages. Mehelya nyassae feeds primarily upon lygosomatine skinks, including many fossorial taxa. Mehelya capensis has a broader diet, feeding on a wide variety of terrestrial lizards (especially agamids and gerrhosaurids) and snakes. Toads are also common prey items. The diversity of prey types taken by M. capensis suggests that these snakes may use ambush predation as well as active foraging. Mehelya is strongly convergent with Asian elapids of the genus Bungarus in its morphology (triangular body shape; powerful jaws; visible interstitial skin), behaviour (nocturnality; reluctance to bite when harassed), and diet (feeding on elongate reptiles, including snakes). Observations of preyhandling and ingestion by captive snakes are needed to clarify possible selective forces for the evolution of the unusual traits shared by these taxa.     

Partial separation of the pituitary proteins of Labeo umbratus, Smith (mudfish)

L. umbratus pituitary glands were partially separated by means of preparative polyacry-lamide electrophoresis and chromatography on DEAE-cellulose and Sephadex G-50. Eight fractions were obtaìned and it was found that fraction 1 contained potent adrenocorticotropic stimulating activity, with a molecular weight in the region of 6000. Fractions 3 and 4 contained potent gonadotropic and a lesser degree of exopthalmic producing activity, with molecular weights in the region of 14 000 to 20 000. Fraction 6 displayed pigeon-crop stimulating activity, with a molecular weight above 30 000. Fractions 7 and 8 displayed M.S.H. and vasopressinoxytocic activity respectively, with a molecular weight in the region of 5500–6500. Fractions 2 and 5 could not be identified. The fractions seemed to be glycoproteins and the results are discussed in relation to previous findings.     

Mitochondrial DNA analyses of the Cape hakes reveal an expanding, panmictic population for Merluccius capensis and population structuring for mature fish in Merluccius paradoxus

The Cape hake species, Merluccius capensis and Merluccius paradoxus are the most important resource of the South African and Namibian demersal fishery, but it is unclear whether there is a single population of each shared by both countries. We analysed the population structure and evolutionary history of these two species using the variable 5' region of the mtDNA control region for 311 specimens of M. capensis and 333 specimens of M. paradoxus sampled between Lüderitz (southern Namibia) to south of Cape Point (South Africa). 107 haplotypes for M. capensis and eight haplotypes for M. paradoxus were recovered. AMOVA and pairwise Phi(st) analyses revealed no structure in M. capensis, however significant genetic differentiation between Namibian and South African 'populations' was detected for M. paradoxus. This was only restricted to mature fish older than 3 and 4 years and not for juvenile fish younger than 3 years. Analyses reveal that M. capensis has undergone population expansion (Fu's Fs=-26.65, P<0.001), possibly within the last 4500-23,000 years, whereas M. paradoxus has not. Our study highlights the utility of genetic markers to unravel the evolutionary history of sympatric species, as well as addressing management issues within regions where commercially valuable fish stocks are shared between nations.     

Modification and miniaturization of Thermochron iButtons for surgical implantation into small animals

Thermochron iButtons are being used increasingly by animal physiologists to measure long-term patterns of body temperature in reptiles, birds and mammals. Typically, iButtons are surgically implanted into the intraperitoneal cavity where they measure and store body temperature together with the date and time from an onboard real-time clock. In 16-bit resolution, the DS1922L iButton can store a total of 4,096 data points over pre-determined sampling intervals. iButtons have proved invaluable in measuring patterns of torpor and hibernation in animals larger than 70 g. Weighing around 3.5 g after potting with wax, iButtons are too heavy and large to implant into animals smaller than 70 g because their weight exceeds 5% of the animal’s total body weight. This paper describes how the stainless steel canister housing the DS 1922L iButton battery and circuit board can be removed to reduce the weight of the components to 1.49 g after waxing (ready for implantation) without compromising the function or battery life of the iButton. The modified iButton can be implanted into animals as small as 20–30 g. Calibration data revealed an offset of ca. 1°C on average, confirming that iButtons must be calibrated prior to implantation.     

Estimation of oxygen-diffusing capacity in the gills of different sizes of a tilapia, Oreochromis niloticus

Measurements on gills of features that affect gas exchange have been studied in relation to body weight in specimens (0.0112–812.3 g) of a tilapia, Oreochromis niloticus . The data were analysed with respect to body weight by means of logarithmic transformations (log Y = log a+b log W ). The slopes ( b ) of the log/log regression lines for the gill area, harmonic mean diffusion distance and oxygen diffusing capacity were 0.777, 0.077 and 0.700, respectively. The gill respiratory area of O. niloticus (Trewavas) increases as the fish develops because the number and bilateral area of secondary lamellae increase. The scaling value for oxygen-diffusing capacity is less than the value for gill area because of the slight increase in harmonic mean diffusion distance with development.     

Effects of Leucaena pallida and Sesbania sesban supplementation on testicular histology of tropical sheep and goats

Thirty Ethiopian highland rams with an average body weight of 23.7kg (S.D.=1.23) and age of 18 months and 25 East African bucks with an average body weight of 18.6kg (S.D.=2.06) and age of 14 months were used to study the long term effects of supplementation with the leaves of Leucaena pallida and Sesbania sesban on testicular histology. Within species, animals were blocked based on body weight and scrotal circumference and randomly assigned, within blocks, to five nutritional treatment groups in a complete randomised block design. All animals were provided with unchopped teff (Eragrostis tef) straw ad libitum and were supplemented with either 150g of wheat bran (control), leucaena (200 or 400g) or sesbania (200 or 400g) leaves for a period of 6 months. At the end of the experimental period, all animals were surgically castrated and testicular samples were collected and prepared for histopathological examination. In sheep 200g S. sesban induced relatively more necrosis of the seminiferous tubules than 200g L. pallida, but with similar degree of tubular degeneration. However, lesions in testis of goats fed on 200g S. sesban and 200g L. pallida did not differ. The effect of 400g S. sesban and 400g L. pallida in sheep indicated that the former hardly induced lesions except depressive effect on spermatogenesis. Similar results were observed in goats. About 400g S. sesban induced milder lesions in sheep and goats than were 200g S. sesban. The lesions were compared and discussed in relation to the phytochemical composition of the supplementary feeds.     

A method for the comparison of morphometrical data on skeletal muscles in young rats of different ages and body weight.

Training affects the properties of skeletal muscles as well as the body weight. Furthermore, the muscle weight and the cross-sectional area of the muscle fibers are related to the body weight. A method is therefore described which eliminates the influence of the body weight on the properties of skeletal muscles and thus allows the real training effects to be studied even if the animals to be compared are of different body weights. It is suggested that this method is useful also for morphometrical studies on organs other than muscle and on experimental situations other than training, e.g. for studies on growth.     

Respiratory surface areas of an air-breathing siluroid fish Saccobranchus (Heteropneustes) fossilis in relation to body size

The surface area of the gills, air sacs and skin have been measured in specimens of different body size and their relationship to body weight fits the equation: area= aW^b . The slopes ( b ) of the double logarithmic plots are 0.746 (gills), 0.662 (air sacs) and 0.684 (skin). The gills are poorly developed and their average weight specific area is less than figures obtained for sluggish marine fishes. The skin has an area about 70% of the total respiratory surfaces (gills+air sac+skin). Nevertheless the greater thickness of the skin leads to a smaller diffusing capacity of the tissue barrier ( D_t ) as compared with the gills and air sac. The air sac area for each ml of air that it contains is about 10.5 cm² which is much lower than figures obtained for lungs of other air-breathing fish and for tetrapods.     

Scaling of lumbar vertebrae in anthropoids and implications for evolution of the hominoid axial skeleton

We investigated allometric relationships between vertebral centrum cranial surface areas and body weight and skeletal lumbar length in extant platyrrhine and cercopithecid species. Platyrrhines have smaller lumbar vertebral centra regarding the cranial surface area relative to their body weight than extant catarrhines. However, the stress to the spine of quadrupeds is not only influenced by the body weight but also its length, which contributes to the amount of bending moment. Our results indicated that platyrrhines and cercopithecids have similar lumbar vertebral centrum surface areas when they are scaled on the product of the body weight and skeletal lumbar length. Platyrrhines generally tend to have relatively short lumbar columns for a given body weight. As a result of this tendency, their vertebral centra appear relatively small if only body weight is taken into account. The centrum surface area is rather constant relative to the product of the body weight and skeletal lumbar length within platyrrhines or cercopithecids, despite the fact that skeletal lumbar length is in itself rather variable relative to body weight. This result indicates that the vertebral centrum articular area, the lumbar column length and the body weight are strongly correlated with each other and that such relationships are similar between platyrrhines and cercopithecids. These relationships were observed using both the zygapophyseal and rib definitions of the lumbar vertebrae. However, they were more clearly observed when the zygapophyseal definition was adopted. It appeared that lumbar vertebrae of Proconsul nyanzae (KNM−MW 13142) had distinctively smaller surface areas relative to its body weight and lumbar length than for platyrrhines and cercopithecids, differing from extant hominoids, which have comparatively larger lumbar vertebrae. In the case of Morotopithecus, the lumbar vertebral surface area seems to be as large as in extant platyrrhines and cercopithecids if it had a reduced number of lumbar vertebrae. It is uncertain whether its lumbar vertebral surface area was as large as in extant hominoids. Electronic Publication     

The energy costs of sexual dimorphism in mole-rats are morphological not behavioural

Different reproductive strategies of males and females may lead to the evolution of differences in their energetic costs of reproduction, overall energetic requirements and physiological performances. Sexual dimorphism is often associated with costly behaviours (e.g. large males might have a competitive advantage in fighting, which is energetically expensive). However, few studies of mammals have directly compared the energy costs of reproductive activities between sexes. We compared the daily energy expenditure (DEE) and resting metabolic rate (RMR) of males and females of two species of mole-rat, Bathyergus janetta and Georychus capensis (the former is sexually dimorphic in body size and the latter is not) during a period of intense digging when males seek females. We hypothesized that large body size might be indicative of greater digging or fighting capabilities, and hence greater mass-independent DEE values in males of the sexually dimorphic species. In contrast to this prediction, although absolute values of DEE were greater in B. janetta males, mass-independent values were not. No differences were apparent between sexes in G. capensis. By comparison, although RMR values were greater in B. janetta than G. capensis, no differences were apparent between the sexes for either species. The energy cost of dimorphism is most likely to be the cost of maintenance of a large body size, and not the cost of behaviours performed when an individual is large.     

长江中、上游铜鱼的生长特性

铜鱼是长江中上游的重要经济鱼类和天然捕捞对象,1990—1995年作者利用在长江中上游收集的1030尾标本,对铜鱼的生长特性进行了研究。其体重和体长的关系为W=0.005413L~(3.113)(r=0.9982),生长方程为L_t=60.0229[1-e~(-0.2325(t 0.6108))];W_t=3261.9137[1-e~(-0.2325(t 0.6108))]~(3.113),体重生长拐点t=4.2龄,相应的体长41.05cm、体重973.03g。按生长指标值分析,阶段生长可明显地划分为两个时期,即4龄前的生长迅速期和4龄后的生长减缓期。因此,天然渔业的捕捞规格应控制在约1000g以上的个体,目前在葛洲坝以下的中游江段主要捕捞幼鱼的现状应该改变。     

Bidirectional introgressive hybridization between Lepus capensis and Lepus yarkandensis

Lepus capensis and Lepus yarkandensis are two well-established hare species with different habitat preferences and obvious morphological distinctions. L. capensis is common and widespread while L. yarkandensis is an endemic species with a restricted distribution in the Tarim Basin of western China. During field sampling, individuals with a distinct phenotype were found in the contact zone between the two species. To understand the origin of these unclassified individuals, we analyzed morphological and genetic data from 700 individuals including L. yarkandensis, L. capensis and the unclassified individuals. Morphological analyses of the unclassified individuals revealed that they lie between L. yarkandensis and L. capensis. Genetic analyses based on species-specific molecular markers (mitochondrial control region and SRY) showed that the unclassified populations have mtDNA and SRY genes from both L. capensis and L. yarkandensis, suggesting that the unclassified populations result from hybridization between the two species. Interestingly, many identical and/or very similar mtDNA haplotypes were shared between L. capensis populations and L. yarkandensis populations close to their contact zones, which further suggests the existence of extensive bidirectional mtDNA introgression. Similarly, we found evidence for SRY introgression, though it existed at a lower level compared to mtDNA introgression.     

The water relations of Lithobius forficatus and the role of the coxal organs (Myriapoda: Chilopoda)

The water relations of the common brown centipede, Lithobius forficatus (L.), are examined with regard to the possible involvement of the coxal organs in water uptake. Centipedes with blocked and open coxal pores are subjected to a variety of dehydration and rehydration regimes and weight change over time measured. Weight loss and regain is related to body surface area and is not influenced by the coxal organs.
The conclusion of the paper is that the coxal organs of L. forficatus do not contribute significantly to the ability of these animals to recover water lost through cuticular transpiration.     

Body composition at vaginal opening in mice as influenced by food intake and photoperiod: tests of critical body weight and composition hypotheses for puberty onset

To determine if photoperiod and food intake influenced age and body composition at vaginal opening (VO), 80 mice were exposed to either 18L:6D (LL) or 6L:18D (SL) and fed either 3.64 g/mouse per day (HIGH) or 2.73 g/mouse per day (LOW) of Wayne Lab-Blox. Treatments began at weaning (21 to 23 days of age). Mice were killed at VO and analyzed for fat, water and protein content. Mice fed the HIGH ration were younger (P less than 0.01; 35.9 vs. 41.1 days) and heavier (P less than 0.001; 17.8 vs. 15.4 g) at VO than mice fed the LOW ration. Neither age nor weight at VO were affected by photoperiod. Fat content at VO was greater (P less than 0.001) for HIGH than LOW. Differences in fat percentage at VO between diet groups were greater for LL (9.7 vs. 7.0%) than for SL (9.1 vs. 8.6%), resulting in a photoperiod X ration interaction (P less than 0.01). Percent water and protein at VO were not significantly affected by photoperiod or diet. Within-group correlations between body weight and age at VO were not significant. Body water/body weight was inversely proportional to age at VO. This resulted from increased fat deposition in older animals of the LL-LOW group and increased percent protein in older animals of other groups. We concluded that dietary intake did not influence age at VO by affecting age at which a critical body weight or fat content were attained. A photoperiod of 18L:6D did not affect age at VO relative to 6L:18D.