Exhalant air temperatures in the Virginia opossum

1. 1.Nasal exhalant air temperature in the adult Virginia opossum averages 20.9°C at ambient temperatures near 20.8°C (relative humidity: 47%) and 15.1°C at ambient temperatures near 9.2°C (RH: 78%). Exhalant air temperature is well below deep body temperature (34.5–35.6°C), indicating counterecurrent cooling of the exhalant air in the nasal passages.

2. 2.The extent of cooling of exhalant air is similar in juvenile (15-week-old) and adult opossums.

3. 3.As judged from exhalant air temperature, the effectiveness of countercurrent cooling is similar in the opossum to that seen in small and medium-sized placental mammals. The question is discussed of whether cooling of the exhalant air in these animals represents an adaptation or a physically inevitable, fortuitous effect.

Ciliary elongation in blastulae of Arbacia punctulata induced by trypsin

Hatched sea urchin blastulae, which have primarily short 25-μm cilia except for some long 40-to 70-μm cilia at the apical tuft, were induced to form long (40- to 70-μm) cilia around most of their circumference when treated with trypsin (0.008–0.1%) or concanavalin A. Other animalizing agents did not induce the formation of long cilia when applied to the normal blastulae. The formation of long cilia by trypsin was both time and concentration dependent. The long cilia first appeared around the apical tuft after 6–8 hr in trypsin (21°C), and by 18–22 hr most of the blastula was covered with the long cilia. Length distribution studies on cilia isolated at various times showed that the percentage of long cilia increased from approximately 10% in the normal blastula to over 66% in the 22-hr trypsin-treated embryo, and indicated that the long cilia formed by the elongation of the original short cilia. Only the blastulae and gastrulae could be induced to form long cilia; the prisms and plutei could not. Once development was inhibited by the trypsin and the first long cilia appeared, the trypsin effect could not be reversed. When blastulae with long cilia were removed from the trypsin for 10 hr, the cilia remained long; when the long cilia were detached, the blastulae regenerated long cilia in the absence of trypsin. The induced long cilia moved poorly, similar to the long, apical tuft cilia of normal embryos. The formation of long cilia by trypsin treatment of sea urchin blastulae provides a model system for studying the mechanisms of ciliary length control.     

The mussel filter–pump – present understanding,with a re‐examination of gill preparations

Filter feeding in mussels is a secondary adaptation where the gills have become W‐shaped and greatly enlarged, acting as the mussel filter–pump. Water pumping and particle capture in the blue mussel, Mytilus edulis, have been studied over many years. Here, we give a short status of the present understanding of ciliary structure and function of the mussel filter–pump, supplemented with new photo‐microscope and scanning electron microscopy (SEM) pictures of gill preparations. Pumping rate (filtration) and pressure to maintain flow have been extensively studied so the power delivered by the mussel pump to the water flow is known (1.1% of total respiratory power), but the actual cost based on gill respiration is much higher (19%), implying that the cost of maintaining of the large gill pump is considerable and that only relatively little energy can be saved by stopping or reducing the activity of the water‐pumping cilia so that continuous feeding with a ‘minimal scaled’ pump is cheaper than discontinuous feeding with a correspondingly larger pump. According to the present view, the pump proper is the beating lateral cilia (lc) on the gill filaments and particle capture is accomplished by the action of laterofrontal cirri (lfc) transferring particles from the main water current to the frontal gill filament currents driven by frontal cilia (fc). Unexplained aspects include retention efficiency according to particle size and the role of pro‐laterofrontal cilia (p‐lfc) placed between the lfc and fc. The structure of cilia and the mode of ciliary beating have been re‐examined in this study by new high‐resolution light and scanning electron microscopy of isolated gill preparations exposed to serotonin (5‐HT) stimulation which can activate the lc and lfc at low concentrations (10^?6 M), but removes the lfc from the interfilament canals at higher concentrations (10^?5 M).     

Effect of anthropogenic feeding regimes on activity rhythms of laboratory mussels exposed to natural light

Anthropogenic disturbance may affect animal behaviour and should generally be minimised. We examined how anthropogenic disturbance (24 h food deprivation) affected circadian rhythms in laboratory mussels Mytilus edulis exposed to natural light in the absence of tides. Repeated measures data were collected on mussel gape angle, exhalant pumping and valve adduction using a Hall sensor system over eight consecutive 24 h periods when exposed to two feeding conditions after 24 h food deprivation. Mussels (fed once per day at either midday or midnight) exposed to natural light showed a clear day–night rhythm with increased nocturnal activity: significantly greater gape angle, increased exhalant pumping and had significantly higher valve adduction rates. However, circadian rhythms were less clear directly after anthropogenic food deprivation, in terms of the circadian rhythm in gape angle becoming significantly more apparent over the following days. Unlike mussels fed at midnight, those fed at midday displayed no significant change in gape angle from the hour before to the hour after they were fed, i.e. mussels given food at midday reacted to this food less than mussels fed at midnight. We suggest that independent of feeding time, laboratory mussels exposed to natural light and free from anthropogenic disturbance increase feeding activity at night because their circadian rhythms are strongly influenced by light levels. This study emphasises that the behaviour of animals in the laboratory and in the wild can be altered by anthropogenic disturbances such as vibrations caused by experimental setups and artificial illumination at night.     

Opposite modulation of capsaicin-evoked substance P release by glutamate receptors

Substance P and glutamate are present in primary afferent C-fibers and play important roles in persistent inflammatory and neuropathic pain. In the present study, we have examined whether activation of different glutamate receptor subtypes modulates the release of substance P evoked by the C-fiber selective stimulant capsaicin (1 μM) from rat trigeminal nucleus slices. The selective NMDA glutamate receptor agonist L-CCG-IV (1–10 μM) enhanced capsaicin-evoked substance P release about 100%. This facilitatory effect was blocked by 0.3 μM MK-801, a selective NMDA receptor antagonist. The metabotropic glutamate receptor agonists L-AP4 (group III) and DHPG (group I) (30–100 μM) inhibited capsaicin-evoked substance P release by approximately 60%. These inhibitory effects were blocked by the selective metabotropic glutamate receptor antagonist (±)-MCPG (5 μM). On the other hand, AMPA and kainate (0.1–10 μM), did not significantly affect capsaicin-evoked substance P release. Thus, substance P release from non-myelinated primary afferents, and possibly nociception, may be under the functional antagonistic control of some metabotropic and ionotropic glutamate receptor subtypes.     

Influence of lignin and its degradation products on enzymatic hydrolysis of xylan

The influence of lignin, lignin model compounds, and black liquor from the kraft pulping process on the hydrolysis of xylan by xylanase was investigated. Addition of vanillic acid, acetovanillone, and protocatechuic acid increased the rate of hydrolysis of xylan by as much as 18–50% at low concentrations, but reached maxima at about 0.05% concentration. Addition of vanillin caused a 15% improvement in xylan hydrolysis, while addition of guaiacol more than doubled the hydrolysis rate. Increasing concentrations of either lignin or black liquor also increased the hydrolysis rate of xylan. Circular dichroism spectroscopy indicated a change in the structure of xylanase in the presence of black liquor.     

The differential effects of short-time glutaraldehyde treatments on light-induced thylakoid membrane conformational changes, proton pumping and electron transport properties

A rapid quench technique utilizing the addition of excess buffer containing free amine groups (Tris, glycylglycine) to the reaction medium has enabled a detailed study of the time-course of glutaraldehyde inactivation on the spinach thylakoid membrane to be undertaken. The following light-induced parameters were inactivated in the sequence: slow transmittance changes (0–5 s) > coupling factor activity (5–20 s) > narrow angle 90° scattering changes (30–60 s). About 20% of PS II activity was lost by this treatment. No effect on activity, proton pumping and proton gradient formation was observed over the time-course studied. A consideration of these effects led to the proposal that the slow, light-induced transmittance changes reflect reversible thylakoid structural changes (unstacking, membrane flattening) in response to electron transport and the consequent proton pumping. The narrow angle 90° scattering changes were considered to reflect directly microconformational structural changes in response to the light-driven proton translocation as previously concluded from other workers.     

Burrow ventilation and associated porewater irrigation by the polychaete Marenzelleria viridis

Burrow ventilation of benthic infauna generates water currents that irrigate the interstices of the sediments surrounding the burrow walls. Such activities have associated effects on biogeochemical processes affecting ultimately important ecosystem processes. In this study, the ventilation and irrigation behavior of Marenzelleria viridis, an invasive polychaete species in Europe, was analyzed using different approaches. M. viridis showed to perform two types of ventilation: (1) muscular pumping of water out of the burrow and (2) cilia pumping of water into the burrow. Flowmeter measurements presented muscular pumping in time averaged rates of 0.15 ml min⁻¹. Oxygen needle electrodes positioned above the burrow openings revealed that muscular undulation of the worm body pumps anoxic water out of the burrow. On the other hand, microscope observations of the animal showed that ventilation of oxygen-rich water in the burrow occurs by ciliary action. The volume of water irrigated by M. viridis appears to vary linearly within the first 24 h incubation, with rates ranging from 0.003 to 0.01 ml min⁻¹. From those rates we could estimate that the time averaged rate of cilia ventilation should be about 0.16 ml min⁻¹. Since the cilia pumping into the burrow occurs in periods of 24 ± 12 min and at 50-70% of the measured time, considerable amounts of water from deeper sediments may percolate upwards to the sediment surface. This water is rich in reduced compounds and nutrients and may have important associated ecological implications in the ecosystem (e.g. affecting redox conditions, organic matter degradation, benthic recruitment and primary production).     

Structure and properties of starch-based foams prepared by microwave heating from extruded pellets

The physical properties of microwave-foamed starch-based pellets, including density, porosity, cell structure, water absorption characteristics and mechanical properties were characterized. It was found that the physical properties of these starch-based foams produced by microwave heating are highly dependent on the raw materials and additives. Foam density decreased significantly after addition of 5.5–10.5% w/w salts, while foams containing nucleation agent (talc) were denser than the control with reduced cell size. A proprietary blowing agent did not affect the foam density markedly. Addition of salts also increased the water sorption of foams and plasticized cell walls. Mechanical behaviour of foamed pellets can be adjusted effectively by controlling the cell structure through using different additives. Mechanical properties of the foamed pellets in the elastic region as well as under large deformation (up to 40% strain) all follow a power–law relationship with foam density.     

Preparation of an (−)-ephedrine intermediate through asymmetric reduction of 1-phenyl-1,2-propanedione by anaerobically pre-treated baker’s yeast

The influence of using an anaerobically pre-treated baker’s yeast on the reduction of (R)-1-hydroxy-1-phenyl-2-propanone (2) and (S)-2-hydroxy-1-phenyl-1-propanone (4) was investigated in comparison with non-pre-treated baker’s yeast reduction (control experiments). We observed that there is no significant difference between the anaerobically pre-treated yeast and the control experiment on the reduction rates of 2. On the other hand, the rate of reduction of 4 mediated by the anaerobically pre-treated yeast is much slower than the aerobic experiment. To improve the regioselectivity of reduction of 1-phenyl-1,2-propanedione (1), a baker’s yeast suspension was pre-treated with nitrogen (60 min) followed by oxygen (20 min), to give 2 in 28–31% of yields (96% e.e.) and 3 in 42–62% (>99% e.e.) after 75–90 min of reaction.     

Lipase-catalyzed acylation of naringin with palmitic acid in highly concentrated homogeneous solutions

Acylation reactions of naringin with palmitic acid were performed by a lipase after formation of highly concentrated homogeneous solutions. Their initial naringin concentration was 840–950 mM, which is 20–60 times greater than that in organic solvent media. The overall productivity of highly concentrated solutions was more than 15 times greater than those of organic phase media. The addition of DMSO (20–40%, w/w) to substrate mixtures lowered the melting temperature of a naringin–palmitic acid mixture (1:1 molar ratio) to about 40 °C. Reactions at 80 °C apparently followed Michaelis–Menten kinetics despite extremely high substrate concentrations. As the temperature increased from 60 °C to 80 °C, the apparent viscosity of the highly concentrated solution decreased remarkably from 4.31 Pa s to 0.063 Pa s. An activation energy of 7.65 kcal/mol obtained in a range of 60–75 °C suggests a diffusion-control. On the other hand, an activation energy of 17.09 kcal/mol in a range of 75–90 °C indicates a reaction-control. The highest product conversion yield of 33% (mol/mol) was obtained in a 10 h reaction at 80 °C. Addition of activated molecular sieves to the highly concentrated solution increased the product conversion yield by 7% (mol/mol), suggesting that the original equilibrium was disrupted by removing water and then a new equilibrium was reached.     

High moisture twin-screw extrusion of sago starch: 1. Influence on granule morphology and structure

Effects of barrel temperature (81–149°C) and screw speed (315–486rpm) on extrusion processing of sago starch in a co-rotating twin-screw extruder under a high moisture system (34–47%) were investigated using response surface methodology. Structural changes were characterised by measuring water solubility index (WSI), water absorption index (WAI), degree of gelatinisation (DG), dextrose equivalent (DE) and high performance size-exclusion chromatography (HPSEC) profiles of the extradates. Thermomechanical processing of sago starch in the twin-screw extruder at the high moisture (34–47%) system led to shearinduced limited degradation and starch phase transitions (a composite melting gelatinisation process). Strong positive correlations between WAI, WSI and DG showed that gelatinisation was the fundamental mechanism in this high moisture system rather than dextrinisation. Processing-induced solubility increased at the expense of water absorption. Low WSI (4.5–18.1%) is ascribed to the presence of structures of either granular crystallite remnants or rearrangement of bonds during extrusion.     

Retention efficiencies of the coral reef sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis determined by Coulter counter and plate culture analysis

Sponges are the dominant organisms on many coral reefs and through feeding they may greatly reduce the concentration of suspended food particles. Retention efficiencies of the tubular sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis were examined on a coral reef located in the Florida Keys. Replicate ambient and exhalant water samples were collected in situ from individuals of each species and analysed using two methods. Retention efficiencies of suspended particles (0.75-18 µm) examined using Coulter counter analysis were similar among the three sponge species, averaging 86%. For all sponges, particle retention decreased as particle size increased from 0.7 to 18 µm. Water samples plated on to Marine Agar produced 54 microbial types. Retention efficiencies of culturable microbes were similar among the three species, averaging 82%. This study suggests that the coral reef sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis play an important role in the transfer of energy between the pelagic and benthic environments.     

The role of calcium channels in substance P-induced contractile response in the rat iris

This study was undertaken to assess the role of calcium channels in the contractile response induced by substance P in the isolated rat iris. Substance P produced graded and sustained contraction in the rat iris. Pre-incubation of preparations with thapsigargin (1 μM), verapamil (1 μM), isradipine (1 μM) or with ω-conotoxin MCIIA (0.1 μM) did not significantly inhibit substance P-mediated contraction in the isolated rat iris. However, pre-incubation of the preparations with nicardipine (1 μM) or ruthenium red (1 mM) caused parallel displacement to the right of the substance P concentration–response curve without affecting its maximal response. In contrast, amiloride (1 μM), markedly inhibited substance P-mediated contraction (73±5%), while econazole (1 mM) also significantly inhibited (44±11%) substance P-mediated contraction in the isolated rat iris. Collectively, these results suggest that substance P-mediated contractile response in the isolated rat iris depends largely on the influx of external Ca²⁺, by a mechanism which might involve the T-type calcium channels.     

Structure-activity studies with fragments and analogues of salmonid melanin-concentrating hormone

A number of cyclic and linear fragments and analogues of MCH were synthesized and their biological potencies tested using the isolated carp scale melanophore assay. In this system, the cyclic portion MCH(5–14) exhibited only 0.1% bioactivity, which was markedly enhanced by the addition of the exocyclic sequences MCH(15–17) and MCH(1–4). The exocyclic sequence itself, MCH(1–4, 15–17), had minimal activity, however. Substitution of Tyr¹¹ with phenylalanine reduced the potency of the ring structure MCH(5–14) by about 4-fold. Substitution of Gly⁸ with D-alanine reduced the potency of MCH(5–14) 16-fold, while both substitutions together caused a still more marked reduction (200-fold) in bioactivity. Linearized fragments of MCH, extending from MCH(15–17) to [Cys(Acm)^5,14]MCH(1–17), showed a progressive increase in potency. The linearized forms of MCH, MCH(5–17) and MCH(5–14), were approximately 100-fold or less potent than their cyclic forms. The significant increases in bioactivity produced by the addition of the C- and N-terminal exocyclic sequence even to these linearized forms further emphasizes the importance of these regions for interaction at the receptor site.     

Differential processing of substance P and neurokinin A by plasma dipeptidyl(amino)peptidase IV, aminopeptidase M and angiotensin converting enzyme

In addition to plasma metabolism of substance P (SP) by angiotensin converting enzyme (ACE; EC 3.4.15.1) (<1.0 nmol/min/ml), the majority of SP hydrolysis by rat and human plasma was due to dipeptidyl(amino)peptidase IV (DAP IV; EC 3.4.14.5) (3.15–5.91 nmol/min/ml), which sequentially converted SP to SP(3–11) and SP(5–11). In turn, the SP(5–11) metabolite was rapidly hydrolyzed by rat and human plasma aminopeptidase M (AmM; EC 3.4.11.2) (24.2–25.5 nmol/min/ml). The K_m values of SP for DAP IV and of SP(5–11) for AmM ranged from 32.7 to 123 μM. In contrast, neurokinin A (NKA) was resistant to both ACE and DAP IV but was subject to N-terminal hydrolysis by AmM (3.76–10.8 nmol/min/ml; K_m=90.7 μM. These data demonstrate differential processing of SP and NKA by specific peptidases in rat and human plasma.     

Testosterone and hydrocortisone-stimulated responses of reduced pyridine nucleotide fluorescence in prostates cultured from castrate rats

1. Addition of testosterone to prostate organ cultures containing 0.1% glucose is followed after 40 to 60 min by a gradual increase in reduced pyridine nucleotide fluorescence. In several experiments oscillations were superimposed upon the increasing steady-state fluorescence level. The average increase in fluorescence was 8.5%.

2. When a similar experiment was done in medium containing 0.05% glucose only a 2% increase in fluorescence was seen.

3. A single addition of glucose to the testosterone-pretreated prostate resulted in an increase in reduced pyridine nucleotide fluorescence of 6%. Stepwise additions of both equal and larger amounts of glucose produced similar but smaller change in fluorescence.

4. Hydrocortisone addition to prostates produced a cycle of fluorescence which began within 2 min, attained a maximum within 5–12 min and was complete within 20–30 min. Addition of testosterone after the hydrocortisone response is complete stimulates an immediate increase in fluorescence to a level 10 to 15% higher than that seen before testosterone addition.

5. N₂-air cycles before hydrocortisone and testosterone showed a change in fluorescence of 4%. After hydrocortisone and testosterone the change in fluorescence in response to N₂ was 9%. This indicated that a doubling of the amount of pyridine nucleotide linked to respiration occurred. However, the increase in the steady-state fluorescence was 15%, indicating that there was an equivalent increase in glycolytic pyridine nucleotide.

6. The addition of 17β-estradiol produced an immediate small increase in the fluorescence signal which can be explained by its intrinsic fluorescence.     

A realistic evaluation of the action of ozone on whole human blood

We have clarified the role of the ozone concentration in relation to the resistance of human erythrocytes in whole human blood or in blood diluted either in saline or in distilled water.

Spectrophotometric data related to haemoglobin were evaluated by exposing samples of fresh human blood directly to ozone doses (ratio 1:1 volume), within the therapeutic range (0.21–1.68 mM) and to one toxic dose (3.36 mM). Furthermore, the same determinations have been carried out after previous dilution of the same blood with either pure water or physiological saline (1 ml blood + 29 ml diluent) followed by ozonation with the above reported ozone doses. Addition of either saline or water implies a dilution of plasma antioxidants and also total haemolysis after water dilution. Particularly the latter case represents a most unphysiological situation because the osmotic shock causes the solubilization of the erythrocytic content. While it is possible to demonstrate that after haemolysis there is an ozone-concentration dependent transformation of some oxyhaemoglobin to methaemoglobin, no such process occurs after ozonation of whole blood.

The results of this study fully confirm our previous data that judicious ozone doses neither damage erythrocytes, nor induce oxidation of intracellular haemoglobin. We hope that our conclusions will definitively clarify the absence of toxicity of ozonetherapy.     

CGRP antagonists and capsaicin on celiac ganglia partly prevent postoperative gastric ileus

The role of capsaicin-sensitive pathways and CGRP in postoperative gastric ileus was investigated. Abdominal surgery was performed under enflurane anesthesia, and 5 min later, the 20-min rate of gastric emptying was measured by the phenol red method in conscious rats. Surgery inhibited gastric emptying by 76–83% compared with rats receiving anesthesia alone. Capsaicin on the celiac/mesenteric ganglia (10–21 days before) reduced gastric ileus by 33 ± 8%, whereas perivagal capsaicin had no effect. The IV CGRP-induced inhibition of gastric emptying was completely reversed by the CGRP antagonist, CGRP(8–37) (30 μg, IV); CGRP(8–37) (15, 30, or 60 μg) or CGRP monoclonal antibody #4901 (2 mg protein) decreased the inhibition of gastric emptying by 11 ± 7%, 51 ± 13%, 47 ± 3%, and 45 ± 17%, respectively. These results indicate that CGRP and splanchnic capsaicin-sensitive afferents are involved in mediating part of the gastric ileus observed immediately after abdominal surgery.     

Transformation of ram spermatid chromatin

In order to investigate the sequence of changes in nuclear basic proteins throughout ram spermiogenesis, we have used different techniques to obtain populations of spermatid nuclei in specific stages of maturation. Sedimentation of testis cells at 1 gravity followed by treatment with Triton X-100 resulted in one population of round spermatid nuclei (steps 1–a), one of non-round spermatid nuclei (steps 8b-15), and one of elongated spermatid nuclei (steps 12–15). Populations of non-round spermatid nuclei were obtained by treatment with EDTA (steps 9–15), by sonication (steps 12–15) and digestion by DNase (steps 13–15). Nuclear proteins, extracted either directly with dilute acid or following a reducing treatment with 2-mercaptoethanol were characterized by polyacrylamide gel electrophoresis.The most striking alterations in protein composition occur during the elongation phase (steps 8–12). The five histones are displaced from chromatin at the same rate. When they are freed of histones (step 12), the nuclei start to accumulate the sperm-specific protein (BNSP) which is then partly extractable by dilute acid without a thiol that is required for its extraction from more mature nuclei. This stepwise replacement process is accompanied by a reduction of the basic protein amount bound to DNA. As soon as histones begin to disappear, eight spermatidal protein fractions are present in the nuclei until the BNSP synthesis reaches its maximum rate. Except for one, they all contain cysteine and are partially intermolecularly cross-linked in the chromatin. After in vivo and in vitro labelling experiments, they are synthesized in elongating spermatids (steps 8–11). None are degradation products of histones.Correlations of the times of onset of EDTA, sonication and DNase resistances with changes in the basic nuclear proteins point out that stabilization and condensation of spermatid chromatin is promoted through a progressive increase in disulfide bridges.