The biochemical composition of the pyloric caeca and its relation to DNA levels in the female starfishAsterias rubens during the reproductive cycle

Summary The biochemical composition of the pyloric caeca of femaleAsterias rubens was studied during the annual reproductive cycle. The amounts of nucleic acids, DNA and RNA were measured in addition to the amounts of lipids, glycogen, other reducing carbohydrates, free amino acids and proteins.A positive correlation of the pyloric caeca index to the biochemical constituents at the cellular level was established. The total DNA content of the pyloric caeca was found to increase with the pyloric caeca index.The relation of the biochemical composition of the pyloric caeca to the size changes of the organ is discussed. The hypothesis that the changes in size of the organ are due to changes both in the number and size of the cells is confirmed. The biochemical composition of the pyloric caeca and its relation to the reproductive cycle is discussed.Abbreviations GI gonad index - CPI pyloric caeca index     

An autoradiographic investigation of the proliferative activity of pyloric caeca and gondas of Asterias rubens

The proliferative activity of the pyloric caeca of Asterias rubens was investigated. Autoradiographic experiments using intracoelomically injected (methyl-³H)-thymidine were performed throughout the year and incorporation into pyloric caeca and into gonads was studied. Tritiated thymidine was found to be incorporated mainly in the coelomic lining of both organs. Cell divisions in the coelomic lining may be necessary for the growth of these organs, for the production of coelomocytes or, in the case of the pyloric caeca, for growth of the digestive epithelium. Proliferative activity of the digestive epithelium of the pyloric caeca was only observed in the median duct. It is hypothesized that new cells, arising from mitosis, grow from the median duct to the side lobes and differentiate into storage cells, for example. The existence of a mitosis-inducing or mitosis-stimulating substance is discussed. In the ovaries follicle cells were found to incorporate (methyl-³H)-thymidine; in the testis, proliferation of the germinal epithelium occurred simultaneously in all spermatogenic columns. First, the spermatogonia and then later the spermatocytes became labeled. Absorption of substances from the coelomic fluid is discussed.     

Allocation of nutrients during the reproductive cycle of Ophidiaster ophidianus (Echinodermata: Asteroidea)

The reproductive cycle of Ophidiaster ophidianus (strictly protected status) from São Miguel Island, in the Azorean Archipelago was studied. The reproductive strategy; the energy allocation of each sex during the reproductive cycle and the nutritional condition of the population were analyzed. Gonadal index (GI) showed a clear seasonal pattern with spawning between August and October but histological examination revealed that gamete release can occur throughout the entire year. The pyloric caeca index (PCI) showed little annual variation but with an inverse relationship with the GI. Allocation of energy to the gonads and to the pyloric caeca reflected the seasonal reproductive strategy of this species. Individuals were able to simultaneously develop gonads, pyloric caeca, and quickly regenerate lost arms. There was a major expenditure of energy by females compared to males but, sexual size dimorphism was not observed. The reproductive pattern observed in O. ophidianus combining rich food availability and seawater temperatures characteristic of a temperate zone may be the key to the success of this species in the Azorean oceanic Island.     

The reproductive cycle of the asteroid Coscinasterias muricata in Port Phillip Bay, Victoria, Australia

The reproductive cycles of two populations of Coscinasterias muricata from Port Phillip Bay, Victoria, Australia are described in terms of organ indices, oocyte development and progesterone levels. Both Governor's Reef and South Channel Fort populations exhibited clearly defined reproductive cycles with two spawning periods, during summer and during spring. In both populations, the pyloric caecal index and gonadal index showed inverse cycles suggesting nutrient translocation from the pyloric caeca to the gonads for gametogenesis. Physiological changes, such as decreases in pyloric caecal index, and increases in gonadal index and oocyte diameter were observed following the months of increased progesterone concentrations in the female pyloric caeca. These results indicate a role for this steroid in the reproductive cycle. The results from the Governor's Reef population suggest that the influence of progesterone on the reproductive cycle of female C. muricata is regulated by photoperiod. Results also provide evidence of a role for seawater temperature in the reproductive process of this species.     

The annual pyloric cycle of Asterias rubens L. (echinodermata: Asteroidea)

Observations of biochemical changes in the pyloric caeca of Asterias rubens L. in different nutritional states and at different stages of the reproductive cycle show the existence of an annual cycle in the pyloric caeca. This pyloric cycle is closely related to that of the gonads. During the gonadal rest (May to September, when the gonads are barely visible) the pyloric caeca grow and store glycogen. During gonadal activity (October to April), they progressively autolyse and first accumulate, then liberate, lipid reserves. This winter pyloric autolysis provides the gonads with the structural material necessary for their annual growth. The summer pyloric growth must be interpreted as the accumulation of the structural material. Under normal conditions, during gonadal rest, the pyloric glycogen reserves ensure the survival of the animal. Pyloric lipid reserves appear only at the beginning of gonadal activity. Their synthesis is intimately related to the start of the gonadal activity of which they are the principal energy source. We believe that the pyloric cycle is under control of hormones that could be transported through the haemal system.The pyloric caeca are the only reserve organs of starfish. Neither the other digestive organs nor the body wall accumulate energy reserves. During starvation of medium duration (2 to 4 weeks) the pyloric caeca suffice to ensure the survival of the animal by liberating their reserve material and simultaneously starting to autolyse. During prolonged starvation, general autolysis occurs and the size of the starfish diminishes.     

Progesterone and oestrone levels in the gonads and pyloric caeca of the male sea star Asterias rubens: A comparison with the corresponding levels in the female sea star

• 1.1. Levels of progesterone and oestrone were estimated by means of RIA in the gonads and pyloric caeca of male specimens of Asterias rubens throughout the reproductive cycle.
• 2.2. The patterns obtained appeared to be sex-specific on comparison with those of female specimens of A. rubens and it was concluded that progesterone and oestrone in the testes are involved in the regulation of gametogenesis.
• 3.3. The levels of progesterone in the pyloric caeca were about ten times higher than those in the testes; in the same sequence levels of oestrone were only slightly higher.
• 4.4. The onset of a new reproductive cycle, taking the abrupt decrease of the pyloric caeca-index as a marker, coincides with a strong decrease of the progesterone level (P < 0.001) and an increase of the oestrone level (P < 0.01) in the pyloric caeca.
• 5.5. It is supposed that progesterone and oestrone in the pyloric caeca are concerned with making available the materials required for gametogenesis.

     

Trace metal burdens and expression of heat stable low molecular mass proteins in the female asteroid Coscinasterias muricata--Fluctuations throughout the reproductive cycle

Concentrations of the essential trace metals copper and zinc were measured in the pyloric caeca of female Coscinasterias muricata sampled from Port Phillip Bay, Victoria, Australia at monthly intervals for 15 months. Results indicate that the concentrations of these metals appear to be regulated by the reproductive cycle. Peaks in zinc concentration occurred simultaneously with peaks in progesterone concentration in the pyloric caeca. These findings suggest that zinc plays a role in gametogenesis and ovarian development. Fluctuations in pyloric caeca copper concentration appear inversely related to the pyloric caecal index and associated with oocyte diameter, indicative of a role for this metal in oogenesis. The levels of cytosolic heat stable low molecular mass (LMM) proteins were examined throughout the sampling period. Heat stable LMM proteins (metallothionein-like) of 12 kDa and 7.5 kDa (apparent molecular mass) and the concentrations of copper appear to be related; although the exact nature of these proteins remains unknown. No such relationship was observed between the levels of heat stable LMM proteins and zinc.     

Physiological correlates of growth and condition in the yellow perch (Perca flavescens)

This study on yellow perch (Perca flavescens) examines a series of enzymatic markers and the relative weights of pyloric caeca and visceral lipids, their response to changes in feeding regime and their potential use to infer recent changes in growth rate and fish condition. Fish were exposed to four different feeding regimes for 12 weeks resulting in specific growth rates ranging from 0.3% to 3.5% (%/day). Growth and condition responded rapidly to changes in ration and the weight of pyloric caeca and visceral lipids reflected increased feed intake. Growth rate was correlated with muscle citrate synthase and caecal nucleoside-diphosphate kinase activities, whereas condition was correlated with muscle citrate synthase and lactate dehydrogenase activities and with caecal glucose-6-phosphate dehydrogenase activity. Results showed that enzyme activities and biometric parameters responded rapidly to increased feed intake, but the response was slower when food intake decreased. Plateaus were attained for both condition and visceral lipid index, but the relative weight of pyloric caeca continued to increase throughout the experimental period. Results from this study could, in principle, be used to infer recent growth and energy status in wild yellow perch and thus provide an indicator of food availability in their environment.     

Seasonal variations in the levels of polyhydroxysteroids and related glycosides in the digestive tissues of the starfish Patiria (Asterina) pectinifera

Seasonal variations in the levels of polar steroids including polyhydroxylated steroids and related glycosides in digestive organs of the starfish Patiria (=Asterina) pectinifera have been studied. The concentration of polar steroids is related to the annual reproductive cycle of the starfish and periods of active feeding. Two peaks in concentrations of polar steroids in pyloric caeca and stomach were found, the first in winter during reorganization and the second in summer during intensive gametogenesis before spawning. Probable biological functions of polyhydroxysteroids and related glycosides are discussed. The data support the hypothesis these compounds are involved in digestion in the starfish.     

Level,content, and caloric equivalents of the lipid,carbohydrate, and protein in the body components of Luidia clathrata (echinodermata: asteroidea: platyasterida) in Tampa bay

The body components of the primitive platyasterid starfish, Luidia clathrata (Say) have been characterized according to season, reproductive, and nutritional condition. The animal has been ‘reconstructed’ in terms of the wet and dry weights, the weight of organic matter, and the caloric equivalents of the body components in early summer (when there are no gonads and the pyloric caeca are small), in autumn (just prior to initiation of gonadal development and at maximal caeca size), and in early spring (at maximal gonad size). The body wall is always the most significant component in terms of wet and dry weights. In terms of organic matter and calories, the pyloric caeca are the most significant compartment in the fall and, together with the gonads, in the spring. On starvation for one month, the decrease in the size of the pyloric caeca is calculated to have produced 2.048 kcal. The energy requirement over the period, calculated from Q_o2 values, is 2.112 kcal. There was no change in biochemical composition of the pyloric caeca with starvation, suggesting that energy production came about through cell destruction rather than preferential utilization of cellular nutrient stores. Lack of extreme change in the composition of the pyloric caeca with size through the year also suggests that energy deposition in the organ is primarily by change in cell number and not by cell size.     

Effects of oestradiol-17 beta on the synthesis of RNA, proteins and lipids in the pyloric caeca of the female starfish Asterias rubens

1. The effects of oestradiol-17 beta on processes of synthesis in the pyloric caeca of female Asterias rubens were studied. 2. In vitro treatment with 2.5 X 10(-7) M oestradiol-17 beta resulted in significantly higher RNA levels. 3. In vivo treatment with oestradiol-17 beta resulted in higher lipid levels in the pyloric caeca, but RNA levels, protein levels and the incorporation of 6-[14C]orotic acid, L-leucine-[14C] and sodium 1-[14C] acetate into RNA, proteins and lipids, respectively were not affected, neither were the indices of the gonads and pyloric caeca.     

Carbohydrases in the digestive tract of the African bony-tongue Heterotis niloticus (Pisces: Osteoglossidae)

The presence of amylase and maltase in the stomach, intestine and pyloric caeca of Heterotis niloticus is demonstrated. Amylase activity was highest in the fore-gut, followed by the pyloric caeca, while the lowest activity was in the hind-gut. Optimum pH for intestinal amylase was 8.45. Sucrase, lactase and cellulase were not detected.     

Pancreatic bile salt dependent lipase from cod (Gadus morhua): purification and properties.

The enzymatic basis for cod digestive lipolysis has been investigated. Lipase activity was found in aqueous extracts from pyloric caeca as well as in pancreatic tissue surrounding the caeca and the bile duct. A bile salt-dependent lipase (BSDL) was purified from either defatted powder of cod pyloric caeca or aqueous pancreatic extracts by combined affinity chromatography on cholate-Sepharose and gel filtration on Sephacryl S-200 HR. By SDS-PAGE analysis the molecular weight of purified cod BSDL was estimated to 60 kDa. The enzyme was totally dependent on bile salts for hydrolysis of insoluble fatty acid esters. Antiserum raised against purified cod BSDL reacted specifically with selected mammalian pancreatic BSDLs by Western blot analysis. Results presented in this paper strongly suggest that the bile salt-dependent lipase is the only pancreatic enzyme involved in lipid digestion in cod. The enzyme has been characterized and compared to human pancreatic BSDL with respect to substrate specificity, temperature- and pH-dependence and inhibitors. Both soluble and insoluble fatty acid esters were hydrolysed and the enzyme was 1,3-specific in hydrolysis of triolein. The enzyme was inhibited by di-isopropyl fluorophosphate and phenyl boronic acid, but not significantly by phenyl methyl sulfonyl fluoride. The cod BSDL is probably homologous to mammalian pancreatic BSDLs.     

Triloborhynchus psilastericola n. sp., a parasitic turbellarian (Fam. Pterastericolidae) from the starfish Psilaster andromeda (Müller and Troschel)

The turbellarian Triloborhynchus psilastericola n.sp. (family Pterastericolidae) occurs in the starfish Psilaster andromeda. On approaching maturation it moves from the host's coelom into the glandular pockets of the pyloric caeca with simultaneous loss of almost the entire ciliation. Mature turbellarians feed on the tissue of the pyloric caeca.     

The relation between feeding and reproduction in Anasterias minuta (Asteroidea: Forcipulata)

Anasterias minuta is an oral-brooding sea star and one of the main predators of intertidal benthos in Patagonia, Argentina. The aims of this study were to: (1) assess the temporal pattern of feeding and brooding, (2) evaluate the effect of body size, tidal height and temperature on feeding and brooding, (3) evaluate temporary changes in digestive and sexual organs and (4) investigate the relationships between the predatory and brooding activities. Females do not feed during the brooding period. Spawning proceeded during March. The brooding period was from March to November, with a maximum in May. The population feeding rate varied seasonally, with a maximum in December and a minimum in May. The feeding rate was positively related to water temperature and sea star size; but not with tidal height. An annual cycle exists for pyloric caeca weight in both sexes; lowest values were found during winter, due to brooding female starvation, and a possible decrease in feeding rate of non-brooding females and males. No inverse relationship was found between the pyloric caeca and gonad weights in females, but a lag of 1 month was observed in males, being the maximal pyloric caeca development before the maximum gonad weight, suggesting nutrient translocation.     

The response of digestive proteases to abrupt salinity decrease in the euryhaline sparid Sparus aurata L

The response of the digestive proteases to abrupt salinity change was studied in juvenile gilthead sea bream (Sparus aurata) for 15 days after transfer from 33 per thousand to 21 per thousand. Salinity decrease affected significantly neither the activity of total acid proteases in stomach, nor the activities of total alkaline proteases and major serine proteases--trypsin and chymotrypsin--in the alkaline part of the intestine. The activity of the major proteases was significantly different between the alkaline segments of the intestine, with the posterior intestine presenting the highest activities followed by the pyloric caeca. This distribution pattern remained unaffected by salinity decrease. Notably, salinity change led to significant alterations in elastase and carboxypeptidase activity. The changes were more prominent in the upper part of the intestine (pyloric caeca and anterior intestine) than in the posterior intestine. In pyloric caeca significant alteration of carboxypeptidase A and B activities was observed, elastase changes were confined to anterior intestine together with alterations in carboxypeptidase B activity, while in posterior intestine the changes were restricted to carboxypeptidase A activity. The results are discussed in relation to the osmoregulatory action of the intestinal segments and dietary protein digestion.     

Fate of ingested leucine and glucose in the sea star,Asterias rubens,during its annual reproductive cycle

• 1.1. The distribution of radiolabel from L-leucine [¹⁴C-UL] and D-glucose [¹⁴C-UL] was measured in the sea star Asterias rubens at 1, 6 and 24 hr after oral administration.
• 2.2. Incorporation of the label from both compounds was observed in pyloric caeca, coelomocytes and ovaries even after an incubation time of 1 hr.
• 3.3. Highest incorporation from both precursors was found in proteins, while substantial radioactivity was present in the amino acids, organic acids and neutral components. Lipids were hardly labelled from leucine and only slightly from glucose.
• 4.4. Radioactivity in proteins and lipids increased with increasing incubation time. No significant differences were found in the distribution patterns of radiolabel during the reproductive cycle.
• 5.5. The data obtained are discussed in terms of current knowledge on the translocation of nutrients in echinoderms.

     

Determination of polyamines in digestive and reproductive tissues of adult Asterias vulgaris (Echinodermata: Asteroidea)

1. The polyamines spermine, spermidine and putrescine were extracted from tissues of Asterias vulgaris and quantitated using thin layer chromatography. 2. In the pyloric caeca, mean (+/- SE) levels of spermine, spermidine and putrescine were 138(15), 86(24) and 415(77) nmol/g wet wt tissue, respectively. In the testes, levels were 95(12), 13(6) and less than 6 nmol/g wet wt. In the ovaries, levels were 105(9), 11(0.8) and 15(8) nmol/g wet wt. 3. High levels of polyamines in the pyloric caeca may be related to secretion or excretion in this tissue. 4. We hypothesize that polyamines will be important in the regulation of cellular activity in these tissues during the annual reproductive cycle.     

Phosphatase activity in the larva of the euryhaline mosquito, Aëdes togoi Theobald,with special reference to sea-water adaptation

The alkaline and acid phosphatases in larvae of the euryhaline mosquito, Aëdes togoi Theobald, were measured and the distribution of alkaline phosphatase was examined histochemically. The optima pH for alkaline and acid phosphatases in the larvae were ≈9.0 and 3.2. respectively. The thorax region showed the highest activity of alkaline phosphatase. The enzyme activity of the thorax of seawater adapted larvae was about twice as high as that of freshwater larvae. When the larvae were transferred from fresh water to sea water, the alkaline phosphatase activity of the thorax increased greatly for 3 days, and thereafter decreased to the normal level of sea-water adapted larvae within seven days. In larvae transferred from sea water to fresh water, the activity of the thorax decreased gradually and after 7 days remained at the level of freshwater adapted larvae. No change in acid phosphatase activity was detected following transfer of the larvae from fresh water to sea water or vice versa. A strong alkaline phosphatase reaction was found only in the luminal border of the gastric caeca in the thorax region. The locality of this enzyme did not vary according to the salinity of environmental water.The activity change of alkaline phosphatase of the gastric caeca is discussed in relation to the absorption of the ingested medium from the gastric caeca.