Relevance of atmospheric odours and geomagnetic field to pigeon navigation: What is the “map” basis?

• 1.1. Pigeon homing is highly affected by olfactory deprivation, as can be seen from an almost complete lack of homeward orientation of initial bearings, from widely dispersed recovery sites, and from a strong reduction of homing success which achieves, in inexperienced pigeons displaced over longer distances, a level of zero.
• 2.2. Orientational deficits can be produced not only by various methods to eliminate the sense of smell, but also by elimination of odorous substances from the ambient air.
• 3.3. It is concluded that the observed deficits result from an interruption of an information flow necessary for navigation, and are not due to some general, nonspecific distraction or reduced motivation to home.
• 4.4. The range of olfactory navigation is large (radius up to 500 km and more), but not unlimited. Within this range, the pigeons do not depend on olfactory stimuli perceived during displacement to the release site.
• 5.5. Despite some controversial discussions of the matter, no experimental findings have been published contradicting the above statements and conclusions.
• 6.6. Experimental interference with perception of the geomagnetic field resulted, under sun (and thus with the sun compass capable to operate), in increased scatter of initial bearings, sometimes in slightly reduced homing speeds, but not in disoriented or poorly oriented recovery bearings and not in reduced homing success.
• 7.7. Correlations between initial orientation and spatial as well as temporal variations of the geomagnetic field, as reported by several authors, are unsuited to prove involvement of geomagnetism in the process of site localization.
• 8.8. It is concluded that atmospheric odours are a necessary component of the pigeons' navigational “map” system, whereas the geomagnetic field is not. It seems unlikely that the latter is involved in this system at all, and if it is, its role is expected to be quite subordinate and redundant at best.

     

Flight effects on certain blood parameters in homing pigeons Columba livia

• 1.1. Various blood parameters were monitored in resting and flown homing pigeons. A homing flight of 48 km lasting 60–80 min did not significantly alter plasma levels of total protein, electrolytes and plasma osmolality, which indicated maintenance of the homeostatic stability of the internal milieu during moderate exercise.
• 2.2. Plasma concentrations of marker enzymes such as alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), laetate dehydrogenase (LDH) and creatine phosphokinase (CPK) that tend to denote muscle damage and metabolic flux in prolonged exercise, were also not altered, thereby indicating the steady state of tissue structure and function during a flight of this magnitude.
• 3.3. Significant increases in plasma levels of uric acid and creatinine and decreases in plasma albumin were observed in the flown pigeons.
• 4.4. The flight-induced increase in blood uric acid could be attributed to increased purine catabolism and the increase in creatinine to increased nucleotide turnover.
• 5.5. It is suggested that the higher uric acid levels should not only enhance water conservation, but may also reduce flight-induced hyperthermia besides acting as an antioxidant defence against oxidative tissue injury.
• 6.6. The rise in creatinine is indicative of the breakdown of phosphocreatine for energy during the initial period of flight prior to the utilization of carbohydrate and lipid as fuels.
• 7.7. The decrease in plasma albumin should account for the albumin as lipid carrier lost in transport to the muscles during flight.

     

Flight-induced increase in circulating levels of melatonin in the homing pigeon

• 1.1. Homing pigeons, receiving regular flight-training for participation in racing competitions, were flown from their usual release site, 48 km away from “home”.
• 2.2. On their return “home” within 60–80 min, blood samples for the measurement of melatonin were taken within 1–3 min of arrival.
• 3.3. Post-flight circulating levels of melatonin were found to be about 82% higher than those of the resting control pigeons without any change in plasma osmolality.
• 4.4. This daytime increase in circulating levels of melatonin suggests that melatonin, by virtue of its known hypothermic effect of facilitating peripheral heat dissipation, could prevent excessive flight-induced hyperthermia.
• 5.5. It is also suggested that the flight-induced increase in plasma levels of melatonin is consistent with the known analgesic and metabolic effects of the hormone.

     

Pigeon homing: Further experiments on shielded lofts

• 1.1. Two series of experiments were performed by rearing homing pigeons in two corridor-lofts in each of which they could perceive winds from one direction only (340 and 160° in the first series, 250 and 70° in the second one).
• 2.2. In the first series the two groups of birds were differently, but not homeward, oriented.
• 3.3. In the second series the birds were homeward oriented only when released from sites lying along the directions from which they could sense wind at the home loft.

     

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.

     

Induction of locomotor behavior in the giant African snail,Achatina fulica

• 1.1. The locomotor-inducting factor of the giant African snail, Achatina fulica, was examined.
• 2.2. Snails showed nocturnal circadian behavior in relative humidity at least over 50%. Although the rhythmicity was independent of light and darkness, it was disturbed easily by hydration, and hydrated snails continued to locomote throughout the day. For induction of locomotor behavior, relative humidity over 50% was the fundamental factor and water is shown to be the limiting factor for the endogeneous circadian oscillator.
• 3.3. The integument of snails showed a higher water permeability. Through the integument, hemolymph osmolality changed easily according to hydration and dehydration from about 120 to 400 mOsm/kg H₂O. Circadian behavior was induced in snails in which hemolymph osmolality ranged from about 130 to 230 mOsm/kg H₂O.
• 4.4. By hydration, hemolymph osmolality in quiescent and estivated snails which have higher osmolality decreased gradually and then they began to locomote according to the degree of dilution, and vice versa. The induction of behavior in these snails was controlled by low hemolymph osmolality.
• 5.5. Together with the endogeneous rhythmicity, water environment was shown to be the key factor for the induction of locomotor behavior.
• 6.6. Based on these results, the mechanisms of the induction of locomotor behavior in terrestrial pulmonates are proposed.

     

The suitability of using cryopreservation of spermatozoa for the conservation of genetic diversity in African catfish (Clarias gariepinus)

• 1.1. The effect of cryopreservation of semen on expected Hardy-Weinberg proportions in the f₁ progeny of selected breeding pairs was evaluated.
• 2.2. Four different African catfish breeding pairs were selected, each pair displaying different heterozygous alleles at the glucose-6-phosphate isomerase-1 or 2 loci.
• 3.3. Equal volumes of ova from each female were artificially inseminated with cryopreserved or fresh semen obtained from males possessing corresponding genotypes.
• 4.4. A comparison of growth rates between f₁ groups of offspring produced from fresh and cryopreserved semen was made.
• 5.5. The G-test for goodness of fit showed no significant differences from expected Hardy-Weinberg proportions for allele frequencies obtained in the f₁ progeny.
• 6.6. The application of cryopreservation for the conservation of genetic diversity is discussed.

     

Hemorrhagic and mojave toxins in the venoms of the offspring of two mojave rattlesnakes (Crotalus scutulatus scutulatus)

• 1.1. The venoms of two Mojave rattlesnakes and those of their offsprings were analyzed for Mojave toxin and hemorrhagic toxin.
• 2.2. The venom of one female, collected in Pima County, Arizona, and the venoms of her six offspring contained hemorrhagic toxin but not Mojave toxin (venom B).
• 3.3. The venom of the second female, captured in El Paso County, Texas, contained both toxins (A + B venom). Of her 10 offspring, five contained venom with both toxins, two had hemorrhagic toxin only, and three contained neither toxin.
• 4.4. Venoms that caused hemorrhage also inactivated complement. A pool of the venoms of the venom B offspring was less toxic than adult pooled venom A.

     

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.

     

Cloning and characterization of rabbit pancreatic colipase

• 1.1. Among the digestive enzymes synthesized by pancreas, lipase is the principle lipolytic enzyme which hydrolyses dietary glycerides.
• 2.2. For its action it requires a coenzyme, colipase.
• 3.3. The molecular mechanisms of the interaction of these two are not fully understood.
• 4.4. Further, molecular events that regulate and influence lipid absorption are ill denned.
• 5.5. The rabbit is the conventional animal model for the study of lipid absorption. We have undertaken the molecular cloning, and characterization of rabbit pancreatic colipase, the coenzyme for pancreatic lipase.
• 6.6. Colipase has been cloned from a gt 11 library of an adult rabbit pancreatic cDNA by probing with an oligonucleotide derived from human colipase sequence.
• 7.7. The total reading frame consists of 321 nucleotides coding for 90 amino acids of the functional protein and 17 nucleotides of the leader peptide.
• 8.8. Northern blot analysis revealed a distinct band around 0.5kb. Comparison with other species revealed an over all homology of 75% at the nucleotide level.
• 9.9. At the amino acid level highest conservation is observed at the lipase-binding region (AA 53–73).
• 10.10. Rabbit enzyme also retained the N-terminal pentapeptide of it preform.
• 11.11. The regions of homology and conservation may aid to define the sites of interaction of colipase with lipase.

     

Analysis of postembryonic development of locomotor activity rhythm by corpora allata implantation in the cricket gryllus bimaculatus

• 1.1. Male crickets Gryllus bimaculatus show a drastic change in circadian rhythm from nymphal diurnality to adult nocturnality, in association with an increase in activity level several days after the imaginai moult.
• 2.2. The corpora allata implantation into male 7th or 8th instar nymphs produced supernumerary instar nymphs in about 30% of the implanted animals, but did not affected the normal development in the remaining animals.
• 3.3. The majority of the supernumerary instar nymphs were diurnal and sexually inactive, although their internal reproductive organs appeared to be fully mature.
• 4.4. The supernumerary instar nymphs became nocturnal with an increase in activity level several days after the imaginai (9th) moult.
• 5.5. The roles of the nervous system in the regulation of the rhythm reversal are discussed.

     

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Locust vitellogenin receptor: an acidic glycoprotein with N- and O-linked oligosaccharides

• 1.1. The locust vitellogenin (VTG) receptor which is embedded in oocyte plasma membranes is a glycoprotein.
• 2.2. With various lectins oligosaccharide units have been identified, among them neuraminic acid linked to Gal or GalNAc, mannose chains, Gal linked to GalNAc or GlcNAc and fucose linked to GlcNAc.
• 3.3. With specific enzymes it could be shown that mannose and most other oligosaccharides are O-linked while others like fucose are N-linked.
• 4.4. Enzymatic removal of all O-linked carbohydrates resulted in a drop of the molecular mass of the receptor protein from 200,000 to 110,000.
• 5.5. A total of N- and O-linked oligosaccharides of 54% was calculated.
• 6.6. The isoelectric point of the receptor was found to be at pH 3.4 increasing slightly after removal of neuraminic acid.
• 7.7. Removal of neuraminic acids destroyed the binding ability for VTG.

     

Action of free radical generating systems upon the biological and immunological properties of caeruloplasmin

• 1.1. Exposure of human caeruloplasmin, an acute phase protein with antioxidant properties, to a mixture of xanthine/hypoxanthine and xanthine oxidase as a source of reactive oxygen intermediates decreased its ferroxidase and ascorbate oxidase activities and its ability to inhibit lipid peroxidation.
• 2.2. Immunological reactivity was also altered.
• 3.3. Exposure to hydrogen peroxide mimicked these effects.
• 4.4. Exposure to low-intensity u.v. irradiation depressed caeruloplasmin's ability to inhibit iron-catalysed hyaluronic acid degradation.
• 5.5. The results may explain the mechanism of the observed inactivation of caeruloplasmin within human rheumatoid synovial fluid.

     

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Analysis of clotting defects in diseased lobsters—I. Alterations in blood parameters

• 1.1. In gaffkemic lobsters kept at 15°C. drastic declines in the hemocyte number and clotting ability occur.
• 2.2. In animals kept at 10°C, although some clotting defects rapidly occur, a high number of amoebocytes is found. Clotting ability reappears after 5 days.
• 3.3. The proportion of each type of hemocyte changes. Numerous hemocytes show morphologic altered features.
• 4.4. Dorsal hematopoietic tissue is as in control lobsters.
• 5.5. Total protein contents are similar in bacteremic or control lobster hemolymphs.

     

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.