The effect of cryopreservation and various cryodiluents on allozyme variation of glucose phosphate isomerase in the F1 progency of african catfish (clarias gariepinus)

• 1.1. African sharptooth catfish individuals, heterozygous for glucose phosphate isomerase (GPI-2), were selected as broodstock by using horizontal starch-gel electrophoresis.
• 2.2. Ova of one heterozygous female were inseminated with cryopreserved and fresh milt from a corresponding male.
• 3.3. Significant deviations from expected Hardy-Weinberg proportions occured for offspring obtained by using cryopreserved milt.
• 4.4. Differences in genotypic variation seems to relate to different cryodiluents and the fertility thereof.
• 5.5. Selection of breeding stock for aquacultural practices based on the above information is discussed.

     

Genetic variability in south african blue wildebeest (Connochaetes taurinus)

• 1.1. We used protein gel-electrophoresis to investigate genetic heterogeneity at 33 protein coding loci in a total of 46 blue wildebeest (C. taurinus) kept under different management regimes.
• 2.2. Average heterozygosity ranged from 2.14 to 4.3% and within-population differences accounted for 97.2% of total relative gene diversity.
• 3.3. Comparatively little divergence was found between animals sampled from populations with very diverse population sizes and management histories, with the largest genetic distance estimated between any two populations being only 0.0021.
• 4.4. We discuss our results with particular emphasis on the influence of management history on genetic diversity and divergence in C. taurinus.

     

Allozyme variation in a wild african elephant (Loxodonta africana) population from the Kruger National Park,South Africa

• 1.1. Blood, liver, heart, testis, skin, eye, muscle and kidney samples were obtained from elephants (Loxodonta africana) in the Kruger National Park during a culling programme in April 1992.
• 2.2. Gene products of 25 protein coding loci in L. africana were examined by horizontal starch-gel electrophoresis.
• 3.3. Eighteen protein coding loci (72%) displayed monomorphic gel banding patterns whereas only seven (28%) displayed polymorphic gel banding patterns.
• 4.4. Average heterozygosity values for adults, youngsters and the total population are respectively 0.058, 0.024 and 0.047.
• 5.5. Relative gene diversities within and between populations are 84% and 16% respectively.
• 6.6. Two population simulation programmes were utilized to predict the duration of the current variability present in this species, based on current genetic variation and gene transfer from one generation to the next.

     

Optical and neural pooling in visual processing in crustacea

• 1.1. Optical pooling is common in crustacean vision, both pooling in the single ommatidium and pooling inputs from many ommatidia by overlapping visual fields.
• 2.2. Optical and neural pooling work together subdividing the eye into different surface regions with different tasks.
• 3.3. Small-fiber and large-fiber systems with corresponding small and large dendritic branching provide a parallel processing system.
• 4.4. Several parallel, integrating channels process that visual information which is needed for high-speed reactions.
• 5.5. Visual fibers receive contributions from other modality inputs like vibration, olfaction or attention neurons. Inputs from mechanoreceptors transmitted over integrating fibers seem to join the signals in the intergrating visual fibers.
• 6.6. The signal for a particular channel is expressed by the pattern of spikes (rather than changes in the mean frequency of spikes) which is modulated by any input variation.
• 7.7. A particular discharge pattern may then be recognized by a command neuron or a muscle ensemble.

     

Environmental and genetic influences on the thermal physiology of Rana sylvatica

• 1.1.|Intraspecific variation in the thermal physiology of Rana sylvatica was examined.
• 2.2.|Heat and cold tolerances of both adult and larval representatives were determined for animals representing populations from New York, Maryland, Kentucky, Ohio, Michigan and Canada.
• 3.3.|In general, frogs from more northern localities exhibited lower heat tolerances.
• 4.4.|There was no evidence of interpopulational differences in cold tolerance. Similar trends were revealed by larval testing.
• 5.5.|Interpopulational differences among laboratory-reared tadpoles suggests a strong genetic component to Rana sylvatica thermal physiology.

     

Comparative study of hemoglobins from different Artemia populations. The influence of temperature on the oxygen equilibria

• 1.1. The P50 values of extracellular hemoglobin (Hb) of five Artemia populations from different geographical origin are affected by temperature.
• 2.2. The free oxygen binding energy is high for all the populations (ΔH between −34.7 and −56.2kj/mol).
• 3.3. A possible correlation between thermal sensitivity of Hb and the ambient temperature of the habitat must be considered very carefully.
• 4.4. The occurence of different quantities of Hb1 (αα chains) Hb2 (αβ chains) and Hb3 (ββ chains) in the different populations possibly influences thermal sensitivity.

     

Allozyme variation in a dimeric esterase of the oriental fruit fly,Dacus dorsalis (insecta: tephritidae), from peninsular malaysia

• 1.1. Seven natural populations of Dacus dorsalis were analyzed for a dimeric esterase by means of horizontal starch-gel electrophoresis.
• 2.2. The electrophoretic phenotypes were governed by nine codominant Est-D alleles.
• 3.3. The commonest allele in all seven population samples was Est-D¹⁰⁰ which encoded an electrophoretic band with intermediate mobility.
• 4.4. The distribution of EST-D phenotypes were in accordance with Hardy-Weinberg expectations.
• 5.5. There was no geographic variation in the distribution of Est-D alleles.

     

Internal reference standards in ionic regulation and the predictability of ionic concentrations in animals

• 1.1. The regulation of ions at similar concentrations in most individuals of a species suggests the existence of internal reference standards.
• 2.2. Few have been identified, but many probably relate to cell membrane properties, including potentials, surface charge densities and equilibrium constants of receptor molecules.
• 3.3. Solubility may sometimes determine the product [Ca²⁺][CO₃²⁻].
• 4.4. Reference standards must generally each relate to more than one ionic species.
• 5.5. For some concentrations, including osmolality, there may be no direct reference standard.

     

Significance of scrotal afferents within the general thermoafferent system

• 1.1.|Switching neurons, in the past referred to as a special scrotal afferent system, intergrate information not only from the scrotum, but from various body areas.
• 2.2.|They are present in male and female rats, as well as in guinea-pigs.
• 3.3.|They are present in midbrain, thalamus, hypothalamus and cortical areas.
• 4.4.|Information processing from the scrotum, is not a special system, but part of the general thermo-and noci-afferent system.
• 5.5.|Switching neurons seem to interact with behavioral, perhaps with autonomic thermoregulatory mechanisms, too.

     

Allozyme variation in the stingless bee Trigona fuscobalteata (hymenoptera,apidae) from Peninsular Malaysia

• 1.1. A population of Trigona fuscobalteata from Peninsular Malaysia was analysed for genetic variation at 9 gene-enzyme systems comprising 13 loci.
• 2.2. Two gene-enzyme systems (phosphoglucomutase and isocitrate dehydrogenase) were polymorphic in the 20 colonies studied.
• 3.3. Isocitrate dehydrogenase was represented by duplicate genes.
• 4.4. The number of loci for several enzyme systems appeared to be different from that reported for the Australian stingless bees.

     

Effects of Size and Geographical Origin on Atlantic salmon,Salmo salar,Mucin O-Glycan Repertoire

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Highlights

• •Atlantic salmon O-glycome expanded to 169 structures in three epithelia.
• •Low interindividual variation amongst all populations and geographical regions.
• •Small variations in glycosylation between geographical locations and fish size.
• •Prominent fucosylation in gastrointestinal mucins from Tasmanian fish.

     

Aquatic ecotoxicology: On the problems of extrapolation from laboratory experiments with individuals and populations to community effects in the field

• 1.1. Ecotoxicology is defined as the study of the effect of toxicants on structure and function of ecosystems.
• 2.2. Properties of individuals and populations in laboratory experiments differ from those in the field with respect to distribution in space and time as well as to genetic structure.
• 3.3. Studies of community response can only be extrapolated to other systems if they include the analysis of the causal chain.
• 4.4. Causal explanations require a system analysis at different trophic levels as well as a modelling of the system and an analysis of sensitivity.
• 5.5. A research project is presented which covers most of the suggested problems.

     

Dehydration does not influence the summer versus winter thermal adaptation changes in rabbits (oryctolagus cuniculus), living in natural photoperiod

• 1.1.|Resting metabolic rate of laboratory rabbits kept indoors is susceptible to seasonal fluctuations and is higher in winter than in summer.
• 2.2.|Thermoneutral zone of rabbits under these conditions may shift downwards in winter and upwards in summer.
• 3.3.|Both of these adjustments in thermoregulation seem to be related to the seasonally changing photoperiod.
• 4.4.|Dehydration does not influence these thermoregulatory adaptive changes.

     

Properties of enzymes hydrating epoxides in human epidermis and liver

• 1.1. Cytosolic and microsomal epoxide hydrolyzing enzymes of human skin and liver were compared and found to be different.
• 2.2. Epidermal and hepatic cytosolic epoxide hydrolases were different in terms of substrate selectivity, pI, inhibitor sensitivity and affinity Chromatographic properties.
• 3.3. Microsomal epoxide hydrolases had the same pIs but different substrate selectivities.
• 4.4. Cytosolic epoxide hydrolase from adults had higher specific activity than that from neonates or cultured epidermis, but lower activity than adult hepatic enzymes.
• 5.5. The sizes of cytosolic epoxide hydrolase from epidermis and liver were similar and lower than that from cultured fibroblasts.
• 6.6. Cytosolic epoxide hydrolase from all sources shared similar antigenic determinants.

     

The influences of individual variations in metabolic rate and tidal conditions on the response to hypoxia in Carcinus maenas (L.)

• 1.1. The oxygen consumption of crabs in normoxic and hypoxic (50% O₂) seawater was measured directly after collection.
• 2.2. The influences of size and lunar cycles were removed by scaling the data.
• 3.3. Strong negative correlations between low individual levels of O₂ consumption and the ability to compensate for hypoxia were apparent in Wicklow (subtidal) crabs.
• 4.4. Compensation for hypoxia was much greater on the flood tide than on the ebb.
• 5.5. Crabs from Roscoff (intertidal) had lower levels of compensation than those from Wicklow.
• 6.6. Size, sex and condition had no apparent effect upon these relationships.
• 7.7. Crabs acclimated to laboratory conditions have not shown this tidal variation in compensation for hypoxia.

     

Investigation of phycocyanin-membrane interaction: Promotion of membrane interactions

• 1.1. In a continuing investigation of phycocyanin-membrane surface interaction, fluorescence quenching experiments were performed with a mixture of two populations of fluorescence probe-encapsulated phospholipid bilayer vesicles in the presence and absence of phycocyanin.
• 2.2. These membrane vesicles were prepared with 1,2-dimyristoyl phosphatidylcholine (DMPC), cholesterol and a probe molecule.
• 3.3. A fluorophore was encapsulated in one population of membrane vesicles, while a quencher was encapsulated in another population of membrane vesicles.
• 4.4. The result was compared with those of experiments in the presence of other biomolecules, including albumin, cytochrome c, hemoglobin, myoglobin or RNA.
• 5.5. Interestingly, a one-third reduction of the fluorescence intensity was observed in the mixture of these two populations of membrane vesicles in phycocyanin's presence.
• 6.6. In contrast, the other biomolecules caused no significant reduction in the fluorescence intensity.
• 7.7. These findings were evidence of a phycocyanin-induced membrane perturbation.
• 8.8. This was further demonstrated by a phycocyanin-induced change in the thermotropic behavior of DMPC vesicles, as measured by differential scanning microcalorimetry.
• 9.9. Such a unique property of phycocyanin is believed to be associated with its known membrane surface-interacting character.
• 10.10. A possible phycocyanin-modulated membrane-membrane interaction was discussed.

     

A comparative study of seafish erythrocytes and agglutinins from seaweeds

• 1.1. To date, only a few authors have assayed the agglutinic activity of marine algae against fish erythrocytes, and in these cases, mainly against freshwater fish.
• 2.2. For the first time, the hemagglutinic activity of 70 seaweeds (29 brown, 37 red and four green algae) against erythrocytes of 16 seaflsh species is reported.
• 3.3. The presence of agglutinins was demonstrated in 100% of algae assayed, against at least one of the different types of erythrocytes tested.
• 4.4. The results obtained confirm the presence of receptors for algae agglutinins on the surface of the erythrocytes of the fish studied.
• 5.5. This could be useful in establishing the origins of fish populations, as these serological differences could distinguish between populations of cultivated and wild fish.

     

Variation in thermally induced melanism in monarch butterflies (Lepidoptera: Nymphalidae) from three North American populations

• 1.As ectotherms, insects often experience varying temperatures throughout their life cycle, and some respond by becoming more or less melanistic (dark coloring) during development to increase or decrease thermal energy absorption as larvae or adults.
• 2.Monarch butterflies (Danaus plexippus) breed in temperate and tropical environments worldwide and are exposed to different average and extreme temperatures in different parts of their geographic range. In this study, we compared variation in thermally induced melanism among monarch butterflies from eastern and western North America and from South Florida.
• 3.We raised the progeny of wild-captured adult butterflies from these populations in a common garden experiment, rearing individuals in cold (19 °C), moderate (26 °C), and hot (32 °C) temperatures to examine population variation in larval and adult pigmentation.
• 4.Across all populations, monarch larvae developed the darkest coloration in the cold treatment and were lightest when reared in hot temperatures. Similar results were observed for measures of adult wing melanism, with the exception of adult females, which developed darker colored wings in warmer temperatures.
• 5.Significant population-level differences in average measures of melanism among larvae and adult butterflies were observed. Larvae from the eastern population became substantially darker in colder temperatures than S. Florida or western larvae. Western larvae were lightest overall, which might be adaptive to high temperatures experienced throughout portions of their summer breeding range. S. Florida larvae showed a lower response to cold temperatures relative to monarchs from either migratory population.
• 6.Population level differences were also observed for thermal responses in wing melanism, particularly among adult females. Moreover, we found significant family level effects for each measure of larval and adult melanism, pointing to a genetic basis or strong maternal effects influencing these traits in monarch butterflies.

     

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Circadian rhythms of determined blood chemistry values in buzzards and eagle owls

• 1.1. Fifteen values were determined in blood samples from six buzzards (Buteo buteo) and six eagle owls (Bubo bubo) over the 24 hr of the day.
• 2.2. Glucose, urea, uric acid, triglyceride and calcium values showed diurnal rhythms in both species. Their respective patterns of diurnal variation were compared.
• 3.3. Phosphorus, cholesterol and cholinesterase levels underwent circadian rhythms only in the buzzards. Albumin/globulin and amylase exhibited diurnal variations exclusively in the eagle owls.
• 4.4. Glutamatic oxaloacetic transaminase, albumin, globulin, total protein and creatinine concentrations did not show diurnal rhythms in either of the species.
• 5.5. Blood values of the different parameters were studied on the basis of the ranges described in birds.