Low Hemolymph Research Articles

Dietary Sugars, Hemolymph Trehalose Levels, and Supernumerary Molting of Manduca sexta Larvae

The influence of selected dietary factors on the prevention of starvation-induced supernumerary larval molt was studied. The incidence of supernumerary molting was greatly reduced when larvae were provided with sucrose during the starvation period. Neither casein nor a diet deficient only in sugar had such an effect. Among the various sugars tested, sucrose and fructose were the most effective in suppressing the supernumerary molt. Mannose and sorbose reduced supernumerary molting to a lesser extent. The percentage of larvae undergoing a supernumerary molt was inversely related to the concentration of sucrose, with 100% of those fed on 1% sucrose and 10% of those fed on 7% sucrose molting into sixth instars. The incidence of supernumerary molting was inversely correlated with hemolymph trehalose concentration but was not correlated with protein concentration. A hypothesis relating low hemolymph trehalose titers with activation of the brain-corpora allata system is proposed to explain the JH titer changes after starvation and during molting cycles.

EFFECTS OF DIMETHYLNAPHTHALENE AND FLUCTUATING TEMPERATURES ON ESTUARINE SHRIMP

ABSTRACT The biological effects of a naturally occurring perturbation were compared with those of a perturbation that may be induced by human activities in the coastal zone. The estuarine shrimp Palaemonetes pugio was exposed for 32 days to fluctuating (18 to 22°C) temperatures (FT), to food contaminated with 2,6-dimethylnaphthalene (DMN) at a concentration to wet weight food of 0.24 microgram per gram, or to both. Relative survival rates were evaluated in a matrix of environmental challenge tests. Resistance to hypoxia plus reduced salinity was significantly reduced by exposure to FT and DMN-contaminated food. The influence of FT was much stronger and obscured the effects of DMN-contaminated food when shrimp were exposed to both perturbations at the same time. The persistent, residual effects of FT and DMN-contaminated food in reducing resistance of Palaemonetes pugio to hypoxia was evaluated after a 16-day recovery period with stable temperatures and uncontaminated food. The harmful effects of FT appeared to be reduced by the period of stable temperatures. On the other hand, shrimp that had ingested DMN-contaminated food before the clean food showed increased resistance to hypoxia. A number of sublethal measurements related to aerobic metabolism were made in order to find an index that would be useful in discriminating the effects of FT from DMN-contaminated food and to determine the affected mechanism(s) that lead to altered survival in hypoxia. No measurement examined could satisfactorily explain the observed effects of FT on resistance to hypoxia, independent of diet regime. However, shrimp exposed to both FT and DMN-contaminated food had increased respiratory rates and oxygen to nitrogen rates decreased metabolic independence from external oxygen, and low hemolymph copper concentrations. Measurements that may be useful in detecting stress resulting from DMN-contaminated food, independent of temperature regime, include nitrogen excretion rates, hemolymph copper, and the relation, between oxygen consumption and external oxygen. After the shrimp had ingested contaminated food for 32 days, the concentration of DMN in their tissues was significantly greater than that in the food. Shrimp kept in FT had higher concentrations of DMN than shrimp held at stable temperatures. Feeding uncontaminated food to contaminated shirimp for 16 days resulted in a significant reduction of DMN in the tissues.

Urine production in the shore crab, Hemigrapsus nudus

Urine production was determined for the crab, Hemigrapsus nudus from an estuarine habitat with a seasonal pattern of high salinity – low temperature in winter and low salinity – high temperature in summer. Urine production was measured in crabs collected during winter and summer and held in two salinities, 25 and 75% seawater. Methods used were (1) blockage of nephropores with the physiological adhesive, methyl 2-cyanoacrylate monomer, and measurement of subsequent weight increase, and (2) rate of inulin excretion over four time periods: 6, 12, 18, and 24 h. Blockage and inulin excretion gave urine production rates of 15 to 17% body weight day−1 in 25% seawater. In 75% seawater urine production was estimated by blockage to be 6% body weight day−1 and by inulin excretion to be 12% body weight day−1. Summer crabs in 25% seawater produced urine at a slightly lower rate than did winter crabs. In 75% seawater, no seasonal difference was apparent. Urine production was independent of wet weight of crab. It is suggested that the lower rate of urine production by summer crabs in 25% seawater compared with winter crabs in that salinity is related to their lower haemolymph – seawater osmotic gradient and is an adaptation to lowered summer salinity.

The Effect of Calcium on Cadmium Uptake by the Shore Crab Carcinus Maenas

ABSTRACT The accumulation of cadmium by the shore crab Carcinus maenas (L.) is to some extent dependent upon the calcium concentration of the external medium. This effect is apparently independent of the overall salinity of the external medium and may at least partially explain previous reports of a ‘salinity effect’. Haemolymph cadmium has a highly significant inverse relationship with the external calcium concentration. This effect is less obvious with other tissues, although the whole body cadmium has a significant inverse correlation with the external calcium concentration. Both the haemolymph and gill show a significant inverse relationship between tissue cadmium and calcium. When postmoult animals were exposed to 20 μ-mol l− 1 Cd in 100% s.w., high concentrations of both calcium and cadmium appeared in the haemolymph. Postmoult animals in cadmium-free sea water generally had a lower haemolymph calcium concentration than intermoult animals, and the rise in haemolymph calcium seen in the presence of cadmium may indicate some degree of competition for ‘deposition sites’ between these two metals.

Änderungen im muster der Haemolymphproteine von adulten Königinnen der Hummelart Bombus terrestris

The soluble proteins of haemolymph during the life cycle from adult bumblebee queens ( Bombus terrestris) were separated by disk electrophoresis on polyacrylamide gels. Twenty-three fractions stainable with amido black were detected. Every phase of the bee's adult life is characterized by a specific pattern of haemolymph proteins. Newly emerged queens have a low haemolymph protein concentration which increases in the first 5 days to a maximum. The high concentration is probably connected with the synthesis of hibernation reserves. Before the beginning of hibernation the concentration of some protein fractions seems to decrease; the concentration of these fractions is low also after hibernation. During the spring the first oöcytes begin to grow and the activity of corpora allata, hypopharyngeal glands, and wax glands reaches a maximum at the time of starting nests. A large increase in the concentration of haemolymph proteins is correlated with the activity of these glands. This high concentration does not change during the whole egg-laying period; however, the concentration decreases to a minimum in old queens with degenerating ovaries. In the protein pattern of ovary homogenate we detected three fractions with an RF identical to haemolymph fractions. Investigations on queens parasitized with the nematode Sphaerularia bombi confirmed that these fractions are yolk material (vitellogenin) taken up by ovaries. In parasitized queens oöcytes do not grow and the fractions are of a much lower concentration than in nonparasitized queens with maturing eggs. Therefore it appears that the parasite injures primarily the corpora allata known to stimulate the synthesis of yolk protein.

The suitability of Melanoplus differentialis for electrophysiological investigation based on hemolymph ionic and anatomical studies

1. 1. Inorganic ionic concentrations of hemolymph were determined, and histological features of the nerve cord investigated in adult female Melanoplus differentialis. 2. 2. Hemolymph ionic concentrations are as follows (in mM) : Na +, 64·9 ± 3·7; K +, 10·6 ± 0·5; Ca 2+, 23·3 ± 5·5; Mg 2+, 9·9 ± 0·4; Cl −, 85·6 ± 1·2. 3. 3. The mean nerve cord weight of females with the body mass range of 1·13–1·95 g was 7·00 ± 1·11 mg; histological studies of the abdominal nerve cord revealed eight giant axons (diameter, 13–20 μ). 4. 4. We conclude that M. differentialis has the following characteristics which make it suitable for microelectrode studies: a low hemolymph Na + concentration, and giant axons in the nerve cord.

The endocrine control of protein metabolism as related to reproduction in the fleshfly Sarcophaga bullata

Females of the fly Sarcophaga bullata require a dietary source of proteins or amino acids to support egg maturation. At emergence the haemolymph protein levels were low and dropped still farther in sugar-fed females during the next 10 days. However, after meat was added to the diet the haemolymph protein concentrations rose and yolk was deposited in the eggs of these females. Ovariectomized (OV −) females had high haemolymph protein levels and large corpora allata. Allatectomy (CA −) after emergence prevented yolk deposition in 30 per cent of the females. Those CA − females which did not deposit yolk had low haemolymph protein levels, whereas those which did deposit yolk had high concentrations. All females CA − at pupation matured eggs and had high haemolymph protein levels. Haemolymph protein concentrations of females after the neurosecretory cells of the pars intercerebralis were removed (NSC −) were similar to those of unoperated females of the same age. The haemolymph of sugar-fed females and that of all males contained six proteins as shown immunologically. Meat-fed, egg-maturing females contained these six proteins plus a seventh protein (the ‘female’ protein). All seven proteins were present in the haemolymph of OV − and NSC − females as well as in those CA − females which deposited yolk. Of the CA − females which did not deposit yolk, the ‘female’ protein was absent in 64 per cent of the cases, but this protein was present in low concentration in the remaining 36 per cent. It is concluded that in Sarcophaga bullata the allatum hormone may be involved in the regulation of protein metabolism and that neurosecretion from the pars intercerebralis serves as a gonadotropin.

Neurosecretory control of haemolymph protein concentration during ovarian development in the desert locust

The changes in haemolymph protein concentration were measured during ovarian development. A high haemolymph protein concentration was found to be correlated with an ‘active’ neurosecretory system and developing ovaries. Cautery of the neurosecretory cells of the brain resulted in a low haemolymph protein concentration; implantation of full corpora cardiaca, and hyperactivity, which releases neurosecretory material, elevated the haemolymph protein concentration. Rearing females with mature males was found to speed up maturation, and increase the build-up of haemolymph protein. The haemolymph amino acid concentration decreased when the protein concentration was high and increased when it was low, which suggests that it acts as a pool for protein synthesis. Three haemolymph protein fractions were demonstrated by electrophoresis; one of these increased greatly after ovariectomy and during yolk deposition and thus seems to be concerned in overian development. A neurosecretory control of protein synthesis is postulated.

Studies On Salt and Water Balance in Caddis Larvae (Trichoptera)

ABSTRACT Survival and regulation in sea-water media was studied in the freshwater caddises Limnephilus stigma and Anabolia nervosa. The majority of larvae did not survive for more than a few days at external salt concentrations greater than about 60 mM./l. NaCI. In sea-water media the haemolymph osmotic pressure increased to remain slightly hyper-osmotic to the medium. The haemolymph sodium level also increased to remain slightly hypertonic to the medium, but the chloride level was maintained hypotonic until just prior to death of the larvae. When the haemolymph chloride concentration was raised above the normal level, the Malpighian tubule-rectal system elaborated fluid in which the chloride concentration was hypertonic to the haemolymph. The system is highly sensitive to changes in the haemolymph chloride level. The regulation of body-fluid composition in the freshwater caddises is compared with that found previously in the euryhaline larvae of Limnephilus affinis. It is suggested that the maintenance of a low haemolymph sodium concentration L. affinis larvae is an important part of the adaptation for survival in salt water.