Effects of photoperiod on sodium flux in Corbicula fluminea (Mollusca:Bivalvia)

• 1.1. A significant diurnal rhythm of net sodium flux was demonstrated in the freshwater clam Corbicula fluminea entrained to either a 12L:12D or 24L photoperiod.
• 2.2. Highest net flux occurred during the dark hours on 12L: 12D. The overall mean net flux over 24 hr was not significantly different from a steady state condition.
• 3.3. Net flux values of clams on a 24L photoperiod were negative and significantly lower than the net flux on a 12L:12D photoperiod.
• 4.4. The 12L: 12D net sodium flux rhythm pattern is similar to rhythmic patterns of other physiological processes in another freshwater clam.

     

In situ perfusion study of sodium transport across the nephridia of a marine invertebrate Sabella pavonia S. (Polychaeta; Annelida)

• 1.1. A suitable perfusion rate (0.110μl/min) was calculated after measuring nephridial volume and urine transit time.
• 2.2. Neither inulin nor albumin were found suitable as water movement markers for nephridia.
• 3.3. There was no net sodium flux through the nephridial wall.
• 4.4. Measurements of net nsodium flux through the nephridia showed that, in normal sea water, Sabella could not transport large amounts of sodium against a concentration gradient. A unidirectional sodium flux of about 10nequiv/min per cm crossed the nephridia.

     

Ultradian oscillation in the heart rate of rainbow trout (Oncorhynchus mykiss)

• 1.1. Ultradian oscillations in the min and hr range on long-term (24-hr) computerized recordings of heart rate in rainbow trout Oncorhynchus mykiss, acclimated to 5, 10 and 15°C water temperature, were investigated. Eight-hour duration time series derived from the heart rate recordings were analysed for their harmonic content in the ultradian band by spectral analysis.
• 2.2. A significant ultradian rhythm at around 0.011 cycles/min (approximately 91-min period) was detected in the power spectral density functions of all the 8-hr duration time series derived from the heart rate recordings at the three experimental water temperatures.
• 3.3. The spectral power of the ultradian oscillation detected in heart rate of trout was found to increase significantly with increasing temperature.
• 4.4. The possible endogenous origin of the ultradian rhythm detected in heart rate of Oncorhynchus mykiss is discussed.

     

A behavioural and neuronal analysis of the locomotory system of Lymnaea stagnalis

• 1.1. During locomotion the pond snail Lymnaea stagnalis (L.) exhibits recurrent cyclical movements; in water this behaviour consists of anteriorly and posteriorly directed shell movements and on land these same movements are coupled with longitudinal contractions and extensions of the foot.
• 2.2. Motoneurones innervating the foot, body wall and column have been identified. The activity of some of these neurones is correlated with shell movements during spontaneous locomotor discharges in reduced preparations.
• 3.3. The structure of these motoneurones has been determined by intracellular injection of the fluorescent dye Lucifer Yellow CH.

     

The action of the venom of Philanthus triangulum F. on an insect visceral muscle

• 1.1. Low concentrations (0.05−0.38 BU/ml) of a crude venom extract from P. triangulum F. potentiate nerve-evoked contractions of the locust hindgut, possibly due to contamination of the venom preparation with proctolin.
• 2.2. Higher venom concentrations inhibit nerve-evoked contractions to a dose-independent plateau level.
• 3.3. The venom has no effect on responses to bath-applied proctolin, but responses to bath-applied L-glutamate are inhibited.
• 4.4. Spontaneous contractions are unaffected by the venom.
• 5.5. It is concluded that the plateau contractions are the result of excitation by non-glutamatergic transmission, and are possibly the result of proctolin release.

     

Calcium binding by sarcoplasmic reticulum and mitochondria isolated from an annelid visceral muscle in relation to whole muscle calcium influx and efflux

• 1.1. Nereis pharangeal visceral muscle is composed of obliquely striated fibres with low mitochondrial density and moderately developed sarcoplasmic reticulum.
• 2.2. Isolated mitochondria and sarcoplasmic reticulum showed moderate passive calcium binding but only low ATP-promoted calcium binding which was inhibited by caffeine.
• 3.3. Whole fibres preloaded with Ca⁴⁵ showed a two compartment efflux. The slow, presumably intracellular, compartment accounted for only 10% of total Ca⁴⁵ activity.
• 4.4. Both acetylcholine and high KCl treatments stimulated calcium influx, causing contractures while calcium-free and EGTA treatments inhibited both these contractures and normal spontaneous contractions.
• 5.5. Lanthanum inhibited normal contractility and KCl contractures. Lanthanum also inhibited Ca⁴⁵ influx but was without effect on Ca⁴⁵ efflux.
• 6.6. It is concluded that there is little calcium storage capacity in these visceral muscle fibres and that normal contractions are strongly dependent upon extracellular calcium influx.

     

Seasonal variation in the rate of evaporative water loss in the kangaroo rat,Dipodomys panamintinus

• 1.1. Evaporative water loss was measured as a function of temperature, season and grouping in the kangaroo rat, Dipodomys panamintinus for a one year period.
• 2.2. Three groups of Panamint kangaroo rats were set up and studied during the various changes in season. The three groups were designated as field, exposed and control. These groups revealed the effects of acclimatization, captive acclimatization and laboratory acclimatization respectively.
• 3.3. There is a highly significant difference in the rate of evaporative water loss in the Field Panamint kangaroo rats during the Fall, Winter and Spring.
• 4.4. In general, the quantity of water loss via evaporation was higher in the female Panamint kangaroo rats.
• 5.5. Water loss via evaporation in the control and exposed groups was least affected by seasonal change.
• 6.6. In comparison to the other two groups, the field male and female Panimint kangaroo rats possessed the highest slope (rate) and mean (quantity) for all seasons.
• 7.7. The combined effect of both grouping and season affects both the rate and quantity of evaporative water loss in the Panamint kangaroo rat.

     

Preliminary studies on the characteristics of phenylalanine and β-methyl-glucoside transport in the tench intestine in vitro

• 1.1. The unidirectional transepithelial fluxes of L-phenylalanine, β-methyl-D-glucoside and sodium ions across emusculated sheets of tench mid-intestine were determined in flux chambers.
• 2.2. No net sodium flux was detectable, but phenylalanine was preferentially transferred from the mucosal to the serosal fluid.
• 3.3. There was also a net movement of β-methyl-glucoside towards the serosal medium, but it was much smaller than that of phenylalanine.
• 4.4. This transport was accompanied by an accumulation of each substrate from the mucosal medium into the tissue to a similar level and against a concentration gradient.
• 5.5. The poor transfer of the monosaccharide into the serosal medium could therefore be attributed to a low permeability of the baso-lateral membrane of the enterocyte for this substance.
• 6.6. The influx of L-phenylalanine and of β-methyl-d-glucoside into the epithelial cells of tench midintestine was examined by incubating slices of emusculated intestine in radioactively-labelled solutions of the substrate for 2 min.
• 7.7. The steady-state uptake was assessed after similar incubations lasting 45 min.
• 8.8. Phenylalanine influx obeys the Michaelis-Menten equation with a K_m of 2.9 mM and is dependent on the presence of sodium ions in the incubation medium.
• 9.9. β-Methyl-glucoside influx reveals the same characteristics with a K_m of 2.0 mM but a considerably lower V_max; in addition, it is inhibited by galactose.
• 10.10. The influx of both substrates is reduced by harmaline, which also inhibits the uptake of radioactive sodium by this preparation.
• 11.11. The steady-state uptake of β-methyl-glucoside is also inhibited by ouabain and by 2.4-dinitrophenol.
• 12.12. These results suggest that the mechanisms for sodium-dependent influx of monosaccharides and neutral amino-acids in the tench intestine are similar to those found in mammalian tissues.
• 13.13. The principal difference appears to involve the release of monosaccharides across the baso-lateral membrane of the enterocyte.

     

Changes in high-energy phosphate metabolism in the water scorpion,Ranatra chinensis,under cold water-warm water stress

• 1.1. To evaluate changes in high-energy phosphate metabolism in the water scorpion (Ranatra chinensis) under restraint and cold water-warm water stresses, in vivo [³¹P]NMR spectra were obtained.
• 2.2. Under restraint stress, arginine phosphate (Arg-P) decreased by 10% after 1 hr and remained at that level thereafter, while β-ATP showed negligible changes over 6 hr.
• 3.3. As the water temperature gradually increased or decreased, the relative concentration of Arg-P decreased due to enzyme regulation.
• 4.4. Repeated cold water-warm water stress, which consisted of repeated 15 min exposures to cold water (5°C) followed by 15 min exposures to warm water (30°C) caused distinct decreases in Arg-P and β-ATP concentration. These decreases were dependent on the frequency of exposure.
• 5.5. Phosphomonoesters (PME) increased not only with restraint stress but also with cold water-warm water stress.
• 6.6. The effect of cold water-warm water stress on high-energy phosphate metabolism was greater than that of restraint stress.

     

Sodium and potassium balance of captive meadow voles (Microtus pennsylvanicus) fed laboratory chow and vegetation diets

• 1.1. Mineral balance was studied in meadow voles (Microtus pennsylvanicus) maintained in the laboratory.
• 2.2. Urine and fecal Na⁺ contents of voles on low-Na⁺ diets were comparable to those reported for other herbivore species, but urine and fecal K levels were higher.
• 3.3. Voles approached Na⁺ balance (input = output) on diets with Na⁺ content as low as 56 ppm.
• 4.4. There was not a clearcut hypertrophy of the adrenal-gland zona glomerulosa in voles maintained on low-Na⁺ diets.
• 5.5. Plasma K content and bone water content were higher in voles maintained on high-Na ⁺ vegetation diets, suggesting expansion of extracellular fluid volume.

     

Effect of eyestalk ablation on oxygen consumption of callinectes similis exposed to salinity changes

• 1.1. The effect of eyestalk ablation on preadults of Callinectes similis exposed to a constant salinity (30%.) and to simulated tidal changes in salinity (30-11 to 30%.) were measured.
• 2.2. In constant salinity, crabs showed a persistent respiratory rhythm, with a maximum oxygen consumption during the day. Under these conditions, ablation significantly increased the respiratory rate but not the rhythm.
• 3.3. In variable salinities, the highest respiratory rates occurred in salinities of 11 and 16%. during the night. In these crabs, ablation of eyestalks and subsequent injection of eyestalk extracts did not alter the respiration rate rhythm.
• 4.4. The circadian rhythm is controlled by the periodicity of environmental changes instead of the influence of eyestalk hormones.
• 5.5. Regulation of metabolism in C. similis associated with osmoregulation involves other neurosecretory organs.

     

The multiplicity of neurotransmitters and neurohormones controlling mytilus muscle

• 1.1. The effects of various biogenic amines on contractions of the ABRM of M. edulis in response to repetitive electrical stimulation, ACh and high K⁺ concentration were examined.
• 2.2. Octopamine, serotonin, dopamine, noradrenaline, tyramine and phenylethanolamine potentiated the contractions of ABRM. Octopamine was found to be the most potent. Histamine did not potentiate.
• 3.3. Phentolamine blocked the potentiating action of octopamine and noradrenaline and partially blocked dopamine, but it did not block serotonin. Phentolamine also blocked the potentiating after-effect of repetitive electrical stimulation on subsequent contractions. It is suggested that octopamine is a neurotransmitter or a local neurohormone which potentiates contraction of the ABRM.
• 4.4. Under certain conditions, high concentrations of dopamine and serotonin inhibited contractions in response to ACh and high K⁺ concentration. Thus, these amines have not only potentiating but also inhibitory action on contraction of the ABRM, in addition to relaxing catch.
• 5.5. It is suggested that a wide spectrum of substances participates in the physiological control of contractility in the ABRM.

     

The Proteome of Pig Spermatozoa Is Remodeled During Ejaculation

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Highlights

• •Proteome of mature boar spermatozoa from cauda epididymal and ejaculated sources were analyzed by iTRAQ-based LC-MS/MS.
• •1,723 sperm proteins identified (974 of Sus scrofa taxonomy).
• •1,602 sperm proteins quantified (960 of Sus scrofa taxonomy).
• •32 Sus scrofa sperm proteins were differentially expressed among sperm sources.
• •The proteome of boar spermatozoa is remodelled during ejaculation.

     

Proteomics Reveals Multiple Phenotypes Associated with N-linked Glycosylation in Campylobacter jejuni

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Highlights

• •Protein N-glycosylation is essential for nitrate reductase (Nap) activity in C. jejuni.
• •Removal of N-glycosylation results in a metabolic switch from Asp to Pro uptake.
• •N-glycosylation is required for optimal chemotaxis towards several substrates.
• •Loss of N-glycosylation reduces survival following temperature and osmotic shock.

     

Chemical cross-links of proteins by using bifunctional reagents

• 1.1. The chemical identification of spatial arrangements of the subunits in oligomeric proteins is exclusively achieved by the analysis of the reaction products of the protein and bifunctional reagents.
• 2.2. Since the pioneer work of Hartman and Wold (Biochemistry6, 2439–2448, 1967) the bifunctional reagent such as bis-imido-esters was first introduced into protein chemistry.
• 3.3. We have listed the non-cleavable and cleavable bis-imido-esters, the N-hydroxy-succinimido-csters and the aryl azides which once photolyzed, become the highly reactive nitrene intermediates.
• 4.4. Different reagents classified as homo- and hetero-bifunctional reagents are also listed.
• 5.5. The advantages and limits of each group as well as their chemical properties are advanced and extensively discussed.

     

Multi-isotype Glycoproteomic Characterization of Serum Antibody Heavy Chains Reveals Isotype- and Subclass-Specific N-Glycosylation Profiles

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Highlights

• •nLC-MS/MS method to analyze immunoglobulin (Ig) N-glycopeptides from human serum.
• •Multi-isotype, site-specific characterization of immunoglobulin N-glycosylation.
• •IgA2 sequence and glycosylation-site variant analyses.
• •Platform to define disease-specific N-glycan signatures for different Ig isotypes.

     

Changes in size,hydration and low molecular weight osmotic effectors during meiotic maturation of Fundulus oocytes in vivo

• 1.1. Gains in the water content of the Fundulus heteroclitus follicle account for over 90% of the total wet weight increase, and consequentially most of the size increase, associated with meiotic maturation.
• 2.2. Increases in intracellular Na⁺ and K⁺ actually exceed the accompanying increases in oocyte water, resulting in net gains in the concentration of these solutes. Changes in oocyte osmolality during maturation are mostly closely paralleled by variations in the concentration of K⁺.
• 3.3. Concentrations of various free amino acids, including taurine, remain constant or decline during maturation.
• 4.4. Taken together, these results suggest that an influx of K⁺, followed by osmotically-obliged water, is a primary cause of water uptake during oocyte maturation in F. heteroclitus.

     

A New Tool to Reveal Bacterial Signaling Mechanisms in Antibiotic Treatment and Resistance

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Highlights

• •Quantitative (phospho)proteome analysis of antibiotic treatment in E. coli.
• •Largest bacterial phosphorylation catalogue.
• •Specific phosphorylation motifs changes during resistance development.
• •Phosphorylation mediated signaling could be a potential target for drug design.

     

Melatonin: A coupling device between oscillators in the circadian system of the ruin lizard Podarcis sicula

• 1.1. Chronic administration of melatonin (in silastic capsules) lengthened the free-running period of the locomotor rhythm and shortened the circadian activity time in Podarcis sicula held in constant temperature and darkness.
• 2.2. Lizards displaying a bimodal pattern of activity invariably became unimodal after melatonin administration.
• 3.3. The results support the hypothesis that melatonin acts as a coupling device between circadian oscillators driving the locomotor rhythm in Podarcis sicula.