Biochemical and physiological aspects of anhydrobiosis

• 1.1. The biochemical and physiological mechanisms which are involved in anhydrobiotic survival have been reviewed.
• 2.2. The physical state of water within hydrated and dehydrated organisms is discussed in relation to the concepts of “free” and “bound” water and to the “vicinal water network model” of Clegg (1979) Cell Associated Water. Academic Press, New York.
• 3.3. Evidence is presented for the replacement of “bound” water by glycerol in dried embryos of Artemia salina, but the role of high glycerol content in the free-living nematode Aphelenchus avenae has yet to be evaluated.
• 4.4. The adaptive significance of trehalose is shown to lie in the fact that because it is a non-reducing sugar, it will not participate in a “browing” reaction between reduced groups of sugars and free amino groups of dry proteins. Trehalose also inhibits “browning” reactions between reducing sugars and dry proteins.
• 5.5. The effect of dehydration on membrane permeability suggests that dried organisms suffer mostly if placed directly into a revival medium due to leakage through structurally deformed membrane systems.
• 6.6. Glycerol and trehalose may interact with lipid membranes and reduce the amount of leakage.
• 7.7. Damage to membranes caused by lipid peroxidation is discussed.
• 8.8. Results suggest that the role of high lipid contents in nematode anhydrobiotes is essentially that of a food reserve, although the morphological distribution of such lipid may be important in maintaining the spatial distribution of body tissues in the absence of bulk water.

     

Electrical-ionic control of gene expression

• 1.1. Changes in turgor, in cell volume, in membrane potential, in intracellular ionic activities and, more recently, in spontaneous electrical activity have been reported to be causally linked to the expression of specific genes.
• 2.2. As a result, it has become clear that changes in membrane properties and/or in the intracellular “ionic environment” can play an important role in generating cell type specific physiological responses which indirectly—or maybe directly—affect gene expression.
• 3.3. Possible targets of the ionic “environment” are: the selective transport across biological membranes; the activity of certain (regulatory) enzymes; the conformation of some (regulatory) proteins; of chromatin; of the cytoskeleton; of the nuclear matrix; the association of the cytoskeleton with plasmamembrane proteins or RNA; the association chromatin-nuclear matrix; protein-DNA and protein-protein interactions etc. All these sites may be instrumental to “fine or coarse” tuning of gene expression.
• 4.4. The exact mechanisms by which changes in intracellular ionic environment are transduced, directly or indirectly, into alterations of the activity of trans-acting factors have not yet been fully uncovered. Changes in the degree of phosphorylation of regulatory proteins and/or of trans -acting factors may provoke fine tuning effects on cell type specific gene expression activity.
• 5.5. The intranuclear ionic environment is difficult to measure in an exact way. It can be influenced in a number of ways. The location of a gene, as determined by the position of the nucleus in the cytoplasm and by the association of chromatin to the nuclear matrix may be especially important in cells which can generate some type of intracellular gradient or in excitable cells.
• 6.6. In some somatic cell types—germinal vesicles may behave differently—the intranuclear inorganic ionic “environment” has been reported to be distinct from the cytoplasmic one. This challenges the widespread assumption that the nuclear envelope is always freely permeable to small molecules and inorganic ions.
• 7.7. It can be expected that the fast progress in the cloning of “electrically” controlled genes, in the identification of trans-acting factors, in their mode of interaction with genes and in the precise localization of genes within the nucleus may soon lead to substantial progress in this domain.

     

Biochemical evidences for two sibling species of genus Myliobatis (chondrichthyes: myliobatidae) in South Brazil

• 1.1. Two morphotypes of Myliobatis from the demersal fishery off the Rio Grande (Brazil) were studied.
• 2.2. Thirty-two alleles were detected and resolved by 27 loci.
• 3.3. Nei's measure of genetic identity was 0.8306 and Thorpe's similarity was 0.6990. Mean heterozygosities observed were 0.1327 for the “DE” morphotype and 0.0409 for the “DL” morphotype.
• 4.4. Seven loci were fixed differently in the two taxa studied. This indicates the existence of a barrier to gene-flow between them, showing that both morphotypes belong to different species.
• 5.5. Jaccard's measure of similarity was calculated and a phenogram with the two morphotypes and M. freminvillii was constructed using isoelectric focusing of total soluble proteins. This showed a higher similarity between the two morphotypes of Myliobatis than M. freminvillii.

     

Characterization of NaK ATPase from the gills of the freshwater prawn Macrobrachium rosenbergii (de Man)

• 1.1. The specific activity of Na-K ATPase was determined from the microsomal preparation of gills dissected from adult Macrobrachium rosenbergii.
• 2.2. Maximal ATPase activity was achieved at a substrate concentration of 0.5 mM ATP.
• 3.3. Optimal enzyme activity was obtained at pH of 7.5.
• 4.4. The Arrhenius plot of Na-K ATPase activity revealed a marked discontinuity at 30°C. “Mg” ATPase activity did not exhibit a marked discontinuity.
• 5.5. The E_a for Na-K ATPase and “Mg” ATPase was 14.6 kCal/mole and 9.31 kCal/mole respectively. Q₁₀ values for Na-K ATPase was 2.34 and for “Mg” ATPase 1.65.
• 6.6. ATPase activity and gill homogenate protein concentration exhibited a linear relationship up to 130 μg protein/ml.
• 7.7. Na-K ATPase activity was inhibited by 10⁻³ M ouabain. It was equally inhibited by the removal of K⁺ from the reaction medium.

     

Alkaline phosphatase from Basidiobolus haptosporosus: Comparison with alkaline phosphatases from rainbow lizard and man

• 1.1. DEAE-cellulose chromatography of mycelial alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) from Basidiobolus haptosporosus, produced three iso-enzymes “A”, “B” and “C”.
• 2.2. Fraction “A” was further characterized and showed maximum activity at pH 10 in 0.1 M sodium carbonate-bicarbonate buffer.
• 3.3. The enzyme was stimulated by Mg²⁺, Co²⁺ and Mn²⁺ and inactivated by Zn²⁺, Cu²⁺, EDTA, citrate and tartrate.
• 4.4. Phosphate ions inhibited it competitively, phenylalanine uncompetitively and urea noncompetitively.
• 5.5. It was heat stable for 60 min at 37°C but labile above 55°C.
• 6.6. Its K_m with p-nitrophenylphosphate was 0.5 mM; its estimated molecular weight was 160,000.
• 7.7. The results are compared with the properties of alkaline phosphatases from the rainbow lizard and man and discussed in terms of a triadic association between the fungus, the lizard and man.

     

Separation and properties of a “Neutral” hexosaminidase from embryonic chicken brain

• 1.1. A “neutral” hexosaminidase has been separated from other hexosaminidase forms (I and II) by DEAE-cellulose chromatography and characterized in embryonic (16-days old) and 1-day old chicken brains.
• 2.2. Its properties differ from those of the forms I and II. It has optimum activity at about pH 6.0 and can be eluted from DEAE-cellulose with 0.25 M KCl only.
• 3.3. It has no N-acetylgalactosaminidase activity and cannot be successfully detected after isoelectric focusing since it is very acidic and completely unstable below pH 5.0.
• 4.4. “Neutral” hexosaminidase is heat-stable at pH 6.0 and is inhibited by chloride.
• 5.5. These properties, very different from those of forms I and II, suggest that this “neutral” form of hexosaminidase would be very similar to known hexosaminidase C separated from other materials.
• 6.6. We have found no significant differences for the above-mentioned three forms in chick embryos (16-days old) in comparison with those from 1-day old chicken.

     

Two kinds of peripheral afferent neurons in the earthworm reflex arc

• 1.1. Two kinds of neurons were identified in the body-wall longitudinal muscle layer of the earthworm, Amynthas hawayanus, by the simultaneous potential recording and Lucifer Yellow-CH injection method with a single microelectrode.
• 2.2. Both kinds of neurons have their somata, neuntes and longitudinal processes imbedded in the longitudinal muscle layer. Those with two circular processes extending into the third segmental nerve trunk are tentatively named “intra-nerve-trunk” neurons and those with four circular processes extending into four setae shafts are tentatively named “intramural” neurons.
• 3.3. Both kinds of neurons responded to electrical and mechanical stimuli applied in an afferent direction to them.
• 4.4. The “intra-nerve-trunk” neuron decreased its response amplitudes to these stimuli after the third nerve trunk was sectioned in correlation to the response amplitude decrease recorded from the nerve trunk after it was sectioned.
• 5.5. The response amplitude decrease due to denervation implies a nonlinear structure of the earthworm reflex circuits.
• 6.6. The “intramural” neurons are believed to be primary sensory neurons connected to the mechanoreceptors in the setae.

     

Compensations for temperature in the activities of digestive enzymes of Periplan eta americana (L.)

• 1.1. Differential thermal acclimatory responses of maximal catalytic rates (V_max) of digestive enzymes have been measured in both sexes of Periplaneta americana adapted to 16 and 32°C.
• 2.2. Salivary amylase of females and gastric protease of males exhibit “translational” acclimation, the former showing a “complete” but the latter only a “partial” compensation. The value of Q₁₀ is not altered in the adaptive response.
• 3.3. An alteration of the thermal coefficient is evidenced by the “translational-cum-rotational” compensation of gastric amylolytic activity, with significant warm acclimation but no cold acclimation in both sexes.
• 4.4. Gastric protease of female cockroaches and gastric lipase of both sexes are characterized by the lack of an adaptive compensation to temperature, while salivary amylase of male appears to manifest an “inverse” acclimation.
• 5.5. Sexual dimorphism in the levels of the activities and in the patterns of thermal acclimation of the digestive enzymes is indicated.

     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Cardiac responses of larval and adult tiger salamanders to submergence and emergence

• 1.1. The ECG of aquatic Amhystoma tigrinum from the Colorado Rocky Mountains was recorded while the animals submerged and emerged in water. Older larvae and metamorphosed adults were compared.
• 2.2. Free-swimming animals of both types showed slight emergence tachycardia when taking a “gulp” of air.
• 3.3. Preventing access to air for 30 min or more resulted in a slight bradycardia in larvae. Some adults responded with increased, others with decreased, heart rate depending on their level of excitement.
• 4.4. Restraining the animals before forced submergence caused a greater bradycardia than when unrestrained.
• 5.5. Low dissolved oxygen accentuated the cardiac responses of larvae to submergence but not in adults.
• 6.6. Atropine only partially blocked the diving responses of both forms.
• 7.7. The degree of submergence bradycardia seems to be a function of the ability to extract oxygen from water. It probably is not an adaptation to diving in these forms. Instead the submerged heart rate in these predominantly aquatic salamanders may be the “normal” rate with emergence tachycardias for breaths of air.

     

Cardiac responses of the anurans,Bufo bufo and Rana pipiens,during behavioural arousal and fright

• 1.1. Electrocardiograms (ECGs) were recorded from B. bufo and R. pipiens whilst behaviourally aroused and frightened.
• 2.2. A tachycardia was exhibited in both states, though in fright it was preceded by a “missed” beat.
• 3.3. The difference between these responses and those of other vertebrates was discussed in relation to the amphibious habit.
• 4.4. It is suggested that the cardiac responses of diving, fright and arousal may have a common evolutionary origin.

     

Amino acid compositions of periostracal proteins from molluscs living in the vicinity of deep sea hydrothermal vents: an unusual methionine-rich structural protein

• 1.1. Two species of hydrothermal vent bivalve molluscs have high glycine content periostraca but that of Calyptogena magnifica is rich in methionine and tyrosine while that of Bathymodiolus thermophilus has the highest glycine content recorded for any natural polypeptide.
• 2.2. The amino acid compositions are compared with other periostracal proteins, as found in species adapted to “normal” environments, in terms of hydrophobic character, polar content and conformational potential.
• 3.3. The significance of the composition and possible physico-chemical characteristics of the hydrothermal species periostraca for adaptation to and protection against the unusual environmental conditions are discussed.

     

Indole-, imidazole- and phenyl-alkylamines in the skin of one hundred and forty american amphibian species other than bufonids

• 1.1. Extracts prepared from dried or fresh skins of 140 American amphibian species, other than bufonids, were subjected to chemical and biological screening in order to determine the presence and concentrations of aromatic biogenic amines.
• 2.2. The most frequent and abundantly occurring amine category was that of indolealkylamines, represented by their prototype 5-hydroxytryptamine and its N-methylated derivatives. Conjugated and cyclized indolealkylamines, typical for the toad skin, were apparently lacking.
• 3.3. Phenylalkylamines were represented by two quaternary ammonium bases: leptodactyline and, very rarely, candicine. Leptodactyline was particularly abundant in leptodactylid frogs of the genus Leptodactylus.
• 4.4. Histamine occurred in trace amounts in different species, in large amounts only in some Leptodactylus species of the “pachypus” section. On the other hand, N-methylated histamines and cyclized histamines (spinaceamines) were confined to the skin of Leptodactylus pentadactylus labyrinthicus.
• 5.5. The possible taxonomical and evolutionary significance of amphibian skin amines is pointed out.

     

Cross-correlation analysis of cerebrobuccal connective activity during Aplysia feeding behaviour

• 1.1. Two “en passant” electrodes were implanted around the cerebrobuecal connective (CBC) of Aplysia and used to record the activity, in the unrestrained animal, under three behavioural conditions; (a) absence of feeding behaviour, (b) appetitive feeding behaviour and (c) consummatory feeding behaviour.
• 2.2. The two simultaneous recordings were subjected to cross-correlation analysis, to subdivide spikes on the basis of their direction and speed of propagation.
• 3.3. There was virtually no CBC activity in the absence of food and feeding behaviour.
• 4.4. During appetitive feeding the metacerebral giant cell (MCC) was active and traffic was heaviest in the cerebral-to-buccal direction.
• 5.5. During consummatory feeding, traffic was also sustained in the buccal-to-cerebral direction; there was a reduction in the activity of the MCC, and a peak in the activity travelling to the cerebral ganglia, in the region of higher conduction velocity, was especially pronounced.
• 6.6. Further analysis showed this peak to have its largest amplitude during the actual ingestion of food and to be the result of the firing of several different units.
• 7.7. CBC traffic in both directions was also activated in one case of “spontaneous” biting.

     

Differential weighting of electrophoretic data in crayfish and fiddler crabs (decapoda: astacidae and ocypopidae)

• 1.1. Muscle proteins from the chelae of six crayfish species and ten species of Uca were compared through disc electrophoresis (split gel technique).
• 2.2. No intraspecies variation of the electrophoretic pattern was found.
• 3.3. In interspecies comparisons all components (bands) were weighted individually and specified as ancestral or derived characters.
• 4.4. In the crayfishes the phylogenetic trees constructed from electrophoretic and classical data were found to be congruent. In Uca some branches of either tree remained undefined. Each tree, however, helped complete the other one.

     

Thermal correlates of foraging-site selection by Chinese pit-vipers (Gloydius shedaoensis,Viperidae)

• 1.Do thermal factors influence foraging-site selection by ectothermic predators? Snake species that obtain their prey from ambush must remain immobile for long periods, precluding overt behavioural thermoregulation; and some “ambush” snakes use thermal cues to detect endothermic prey. Plausibly, alternative ambush sites might differ either in equilibrial body temperatures available to snakes, or in the thermal “background” against which prey items must be detected.
• 2.We examined this topic with field data on pit-vipers (Gloydius shedaoensis) on a small island in northeastern China. Adult snakes feed only on migrating passerine birds. The snakes ambush birds both from arboreal perches (branches of small trees) and from the ground.
• 3.Arboreal versus terrestrial ambush sites differed both in operative temperatures and thermal “backgrounds” available to the snakes. Operative temperatures inside copper models were lower in trees than on the ground (because of wind), and snakes in arboreal ambush sites were cooler than those in terrestrial sites. Thermal backgrounds from arboreal perches were cooler (and thus, provided more contrast against prey items) than did backgrounds available from terrestrial ambush-sites.
• 4.Thermal factors thus modify the suitability of alternative ambush locations for these pit-vipers, but with a trade-off: a snake in a tree can “see” its prey more clearly, but may not be warm enough (and hence, able to strike fast enough) to capture it. Further work is required to determine whether or not snakes actually use such thermal differences as criteria for the selection of ambush sites.

     

Variations in response to environmental hypoxia of different colour forms of the shore crab,Carcinus maenas

• 1.1. The oxygen consumption of red and green Carcinus in normoxic and hypoxic sea water was determined, using an oxygen electrode in a sealed respirometer.
• 2.2. The red crabs had significantly higher “excited” oxygen uptake rates and a lower ability to compensate for hypoxia than the green crabs.
• 3.3. Red Carcinus display an emersion response to declining oxygen at lower oxygen tensions than the green crabs.
• 4.4. Mortality of red crabs exposed to prolonged anoxia was much greater.
• 5.5. The relationship of these findings to the zonation of the two colour forms on the shore is discussed.

     

Electrotonic coupling within a cluster of neurosecretory endogenous oscillators in Lymnaea stagnalis (L.)

• 1.1. Double intracellular and extracellular recordings from cell bodies and axons were made to study the interactions between the neurosecretory “Light Yellow” bursting pacemaker cells (LYC) in the right parietal ganglion of Lymnaea stagnalis.
• 2.2. The LYC are interconnected by low efficiency, non-rectifying electrotonic junctions, transmitting low frequencies only.
• 3.3. Often bursts in different cells coincide; apparently the junctions are responsible for this coherence.
• 4.4. It is inferred that the coupling serves to bring about a pulse-wise release of the cluster's secretory product.

     

Haemoglobin metabolism in mice with a hereditary iron deficiency anaemia (sla/Y)

• 1.1. Haemoglobin was labelled in vivo in normal mice and in mice with iron deficiency anaemia due to the X-linked gene mutation, sla.
• 2.2. Two main red cell populations are found in normal mice, one subject to accelerated destruction and the second with a longer finite life span.
• 3.3. In iron deficient sla / Y mice, haem and globin labelling indicate random haemolysis and shortened red cell survival.
• 4.4. Specific activity curves of faecal urobilinogen show complex “early” labelling patterns. They confirm mean red cell survival in both normal and anaemic mice. and indicate increased ineffective erythropoiesis in the sla/Y animals with iron deficiency.

     

Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Identification of components of apparent SDA and effects of dietary amino acid quality and content on SDA

• 1.1. Specific Dynamic Action (SDA) effects of diet were investigated in the supralittoral isopod, Ligia pallasii, using defined chemical diets.
• 2.2. “Apparent SDA”, or the total rise in metabolic rate following a meal, was resolved in animals eating a nutritionally complete chemical diet into three components: 8% mechanical costs of moving food through the gut, 40% “excitement costs” due to investigator disturbance and presence of food, and 52% SDA.
• 3.3. Excitement costs in animals exposed to food but which chose not to eat showed non-significant variation between diets containing different levels of chemical nutrients, but were significantly less on a diet containing only cellulose and agar.
• 4.4. SDA increased with increasing concentration of amino acids in the diet.
• 5.5. Substitution of whole-protein casein for free amino acids in the diet had no significant SDA effect, while substitution of free amino acids in the ratio found in casein more than doubled the SDA effect.
• 6.6. Deletion of alanine from the diet caused no significant effect on SDA, while deletion of phenylalanine caused a highly significant elevation in SDA.