摘要:

AbstractThe concentration of plasma nonhaem iron and the concentration and weight of all nonhaem iron in the whole body and selected organs, together with its partitioning into ferritin and haemosiderin iron, have been measured during the metamorphosis and upstream spawning migration of the Southern Hemisphere lampreyGeotria australis. Some nonhaem iron was lost from the animal during metamorphosis. However, the concentration and weight of nonhaem iron in the liver rose sharply at this time, following its release from important storage sites in adipose tissue and the degradation of larval haemoglobins. The nephric fold of larval and metamorphosing stages contained over 40% of all nonhaem iron in the body at the commencement of metamorphosis. This was predominantly in the form of haemosiderin. While the rise in liver iron during the transition from larva to adult primarily reflected an increase in the weight of ferritin iron, the amount of iron stored as haemosiderin rose conspicuously towards the end of metamorphosis. The rise in ferritin iron in the liver was accompanied by a decrease in ferritin iron in the plasma, which implies that changes in the liver during metamorphosis result in a greater filtering of circulating ferritin. Such a process would account for the very much lower plasma nonhaem iron concentrations which characterise later adult stages. The weight of nonhaem iron increased markedly in the liver and adult opisthonephros and in the whole animal during the nontrophic upstream spawning migration. This was primarily due to a marked rise in ferritin which in turn could be related to the degradation of adult haemoglobins. The concentration of nonhaem iron (54,700 μg/g) and of its ferritin component (52,300 μg/g) in the liver of animals approaching sexual maturity are apparently by far the highest yet recorded for any vertebrat

ISSN:0022-104X    

DOI:10.1002/jez.1402370202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractGroups of rainbow trout (Salmo gairdneri, Richardson) were continuously swum at 20 cm s−1(1.0 body lengths s−1) for 0, 3, 30, and 200 days. No significant changes in fish condition factor, combined red and white muscle mass, muscle fibre size or fibre size distribution were observed. After 200 days of swimming there was a significant 2.2 fold increase in red muscle mass.Number of capillaries per red muscle fibre increased significantly in each group by a maximum of 27% after 200 days exercise. Number of capillaries per white muscle fibre increased significantly by 95% after 200 days exercise. Blood lactate, haemoglobin (Hb) concentration haematocrit, erythrocyte adenosine triphosphate, and whole blood oxygen affinity P50were unchanged by swimming. After 30 and 200 days swimming there was a shift in expression of white muscle lactate dehydrogenase (LDH) isozymes from LDH‐A to LDH‐B. Within the duplicated LDH‐B isozyme complex, there was a shift in expression from LDH‐B to LDH‐B′ subunits. These results suggest that sustained swimming at 1−1bl s−1increased the aerobic capacity of red and particularly white (fast) muscle of rainbow trout but did not alter the gas transport character

ISSN:0022-104X    

DOI:10.1002/jez.1402370203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractUnequivocal demarcation between immature, nonmigratory yellow eels and migratory silver eels of greater sexual maturity is possible by measuring eye diameter and retial capillary length, which undergo a 1.5‐ and 2.3‐fold increase during metamorphosis, respectively. Anatomical arrangement of trunk musculature is similar in the two groups except for an increased depth of slow muscle in silver eel. Histochemical analysis reveals a progressive increase in numbers of “displaced” fast fibres within slow muscle of the lateral line triangle in maturing eels, although these are unlikely to affect recruitment pattern of muscle fibre types. Previous studies have suggested greater involvement of fast muscle in locomotion of migratory eels. In contrast, estimates of enzyme activity in fast muscle suggest an inadequate aerobic capacity to fuel sustained activity. Myoglobin content is extremely low, around 0.4 nM g wet wt−1. Prolonged anaerobic metabolism is also discounted as a migratory strategy. Increased energy provision for migration is apparently derived from increased capacity for both aerobic carbohydrate metabolism and mitochondrial fatty acid oxidation within slow muscle of silver eels. Activity of hexokinase (HK) shows a 1.6‐fold increase (to 0.51 μM g wet wt−1) and carnitine palmitoyltransferase (CPT) a 3.1‐fold increase (to 0.22 μM g wet wt−1min−1), suggesting a maximal flux through these pathways of 18 and 14 ATP equivalents, respectively. However, the fatty acyl transferase system of skeletal muscle mitochondria displays up to threefold greater activity with palmitoleoyl CoA (C16:1) as substrate than with the usual palmitoyl CoA (C16:0). Slow muscle of silver eel is therefore capable of deriving aerobic energy from free fatty acids and carbohydrate in the ratio 2.3:1. Differences in aerobic enzyme activities are not paralleled by myoglobin content of slow muscle, being 15 and 16 nM g wet wt−1for yellow and silver eel, respectively. Structural reorganization of muscle fibres during metamorphosis, however, results in a twofold elevation of cytoplasmic myoglobin concentration in silver eel. It would appear that dramatic differences in metabolic capacity between life history stages of eel is required to overcome locomotory inefficiency of yellow eels and to “preadapt” silver eels for migratory activity. This increased locomotory capacity may be amplified by a s

ISSN:0022-104X    

DOI:10.1002/jez.1402370204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe level of body hydration in the terrestrial slugLimax maximusmodifies several aspects of behavior such as pneumostome activity, feeding responsiveness, huddling, and contact‐rehydration. The relationship between water balance and pneumostome activity and respiratory function suggested that cardiac activity might also be affected. To pursue this possibility, intact slugs and isolated heart‐central nervous system (CNS) preparations were used to investigate cardiac responses to the increase in hemolymph osmolality which occurs during dehydration. In intact animals, heart rate increased in response to progressive air‐dehydration and to increases in hemolymph osmolality resulting from injections of hyperosmotic solutions of mannitol or NaCl. In isolated preparations, the heart or CNS were separately exposed to hyperosmotic saline. Exposure of the heart alone to hyperosmotic saline resulted in decreased heart rate while exposure of only the CNS resulted in an increase in heart rate. These observations suggest that the increase in heart rate that is observed in intact air‐dehydrated slugs is primarily mediated by

ISSN:0022-104X    

DOI:10.1002/jez.1402370205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractDuring mastication the adult pig masseter contracts with a complex pattern involving a wave of electromyographic (EMG) activity moving from the ventro‐rostral corner to the dorso‐caudal corner. The present study was undertaken to ascertain the ontogeny of that contraction pattern. Anatomical measurements were made on masseters from fetal, infant, and juvenile pigs. EMG activity from different parts of the masseter was recorded along with oral movements in infant and juvenile pigs as they suckled, drank, and chewed on food and non‐food objects. The basic arrangement of muscle fibers and tendinous aponeuroses was found to be the same in all ages. The longest and most vertical fibers were found rostrally and ventrally, whereas the shortest and most horizontal fibers were found caudally and dorsally. The length of fasciculi decreased with age, relative to muscle weight. Variance in length among different parts of the muscle increased with age. Fetal masseters were oriented generally more horizontally than the masseters of older animals, except that the dorso‐caudal corner, usually the most horizontal portion, is not developed in fetuses. The contraction patterns within the infant masseter were less complex than those of older animals; only the dorso‐caudal corner was distinct. The further development of intramuscular differences in activity may be associated with the increasing anatomical complexity of the masseter, which augments its functional cap

ISSN:0022-104X    

DOI:10.1002/jez.1402370206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractMoth wing epithelium has a well‐defined apicobasal polarity expressed in the positioning of specialized junctions and microfilament bundles. This cytoarchitecture predisposes epithelial monolayers to fold with their basal surfaces outermost. However, a given epithelial population appears not to be constrained by its cytoarchitecture to fold in a particular direction. Direction of folding—either with basal surfaces or apical surfaces outermost—is determined by environmental factors and is correlated with changes in lateral cell contacts as well as dimensions of the apicalmost epithelial junctions (belt desmosomes). These configurational changes of epithelial sheets are accomplished without altering the intrinsic polarity of individual epithelial

ISSN:0022-104X    

DOI:10.1002/jez.1402370207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractEpidermal cells were dissociated from tails of the bullfrog tadpole,Rana catesbeiana, and cultured to investigate their response to steroid and thyroid hormones. Charcoal‐treated serum (CTS) was used in the growth medium when cells were to be grown in the absence of steroid and thyroid hormones. The cells could be maintained for 2 weeks with a small increase in cell number in medium that contained CTS (CTS medium). Addition of cortisol to CTS medium increased both cellular attachment to the culture dishes and the proliferation of the attached cells with an optimum concentration of 5 × 10−7M. The cells remained viable and attached for at least a week. Cortisol stimulated the rate of protein synthesis 1.8‐fold but did not alter the rate of DNA synthesis. The cells did not proliferate in the medium containing triiodothyronine (T3) and detached themselves from the dish within 5 days, which occurred in a dose‐dependent manner with a maximum effect at 10−8M. It drastically decreased the rate of DNA synthesis but did not influence the rate of protein synthesis. These responses of cells to cortisol and T3may reflect growth and death of tail epidermal cells in vivo at met

ISSN:0022-104X    

DOI:10.1002/jez.1402370208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractSeveral times throughout the year, changes in serum growth hormone (GH) levels over a 24‐h period were determined in goldfish maintained under photoperiods and temperatures simulating natural (Edmonton) environmental conditions. In the goldfish a reproducible daily rhythm in circulating GH levels was not present at any time of the year. The average serum GH level over the daily sampling period and the instantaneous relative growth rate in goldfish sampled at the various times of the year were also determined. The highest mean daily serum GH levels were found in March and June, whereas the lowest level was found in goldfish sampled in November. Changes in mean daily serum GH levels were closely correlated to seasonal changes in daylength. The highest growth rate was found in goldfish sampled in July, whereas the lowest growth rates were found in February and March. Female goldfish exhibited a faster growth rate than male goldfish at certain times of the year, but sexual differences in growth rate were correlated with sexual differences in serum GH levels only in November when female goldfish had a higher serum GH level than male goldfis

ISSN:0022-104X    

DOI:10.1002/jez.1402370209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractHistocompatibility in natural populations of individuals was examined for the following four Japanese species of freshwater sponges:Ephydatia fluviatilis,Ephydatia muelleri,Radiospongilla cerebellata, andEunapius fragilis. Gemmules were obtained from field‐grown specimens. Then, using juvenile sponges hatched from gemmules, fusibility was tested in the laboratory. Every interspecific combination among these four species displayed non‐fusion with no cytotoxic interaction. For all species, the occurrence of allogeneic histoincompatibility was assured, but manifestation of incompatibility was different from species to species. Among 36 specimens ofE. fluviatiliscollected from three localities, two strains nonfusible with each other were distinguished. Each locality was populated by a single strain. Specimens ofE. muelleriwere obtained from two localities. All combinations of specimens coming from the same locality were compatibly fusible, but those between specimens coming from different localities displayed conspicuous cytotoxic rejection reaction. This reaction occurred asymmetrically, resulting in the destruction of one partner. InR. cerebellata, two types of reactions, fusion and rejection, were also distinguished. In rejection, cytotoxic reaction occurred bilaterally and symmetrically in and around the contact zone. A total of 40 specimens, collected from a single pond, could be divided into 16 groups by their fusibility. As toE. fragilis, some combinations of specimens were compatibly fusible; the others displayed various degrees of incompatibility. In completely incompatible combinations, the paired sponges simply showed nonfusion with no sign of cytotoxic reaction. In more weakly incompatible combinations, the paired sponges were separated after initial fusion, the degree of which was variable depending on combination. A total of 59 specimens, collected from a single pond, could be classed into 14 groups by their fusibility. In bothR. cerebellataandE. fragilis, some intergroup combinations were compatible, giving rise to probable genetic chimeras. Such chimeric sponges persisted with no sign of segregation for more than 1 month in the fi

ISSN:0022-104X    

DOI:10.1002/jez.1402370210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIntracellular, loosely bound Ca+ +has been localized electron microscopically in freshly ejaculated boar spermatozoa by in situ precipitation with potassium antimonate. Ca+ +was identified as the cation precipitated by testing the EGTA‐sensitivity of the precipitates and by X‐ray microprobe analysis. The data obtained revealed that the outer acrosomal membrane is the preferential site for Ca+ +precipitation in the sperm h

ISSN:0022-104X    

DOI:10.1002/jez.1402370211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY