Reserve Organs Research Articles

Anti-shock effect of acth-(1–24): Influence of subtotal hepatectomy

Subtotally hepatectomized or sham-operated rats were bled to hypovolemic shock (mean arterial pressure = 18-25 mmHg) and then treated with an intravenous bolus injection of ACTH-(1-24), 160 ug/kg. The treatment caused a prompt and sustained reversal of hypotension, with survival of all sham-operated animals, at least for the first 2 h, while in hepatectomized rats the arterial pressure increase was negligible and there was a 50% mortality within 2 h after treatment. Moreover, the blood volume which could be drained from an arterial catheter prior to death, measured 15-20 min after ACTH injection, was 1.51 +/- 0.12 and 0.64 +/- 0.11 ml/100 g b.w. in sham-operated and hepatectomized rats, respectively. These results further support the idea that the effect of ACTH in haemorrhagic shock is due to the mobilization of blood pooled in peripheral reserve organs.

Food Habits of the Jamaican Lizard Anolis opalinus: Resource Partitioning and Seasonal Effects Examined

A stomach analysis of 340 lizards collected in 33 samples over a 12 month period showed that Anolis opalinus eats arthropods, primarily ants by number (70%). By volume, however, ants comprised only 12% of the food bulk, with lepidopteran larvae and orthopterans being the main food items (46%). The lizards fed predominantly on soft bodied prey, except for ants. We found almost no evidence for food niche partitioning in the size dimorphic A. opalinus. All age and sex classes of lizards had eaten similar sized prey and prey taxa. When a significant difference was detected among classes, it was frequently the smaller lizards which had eaten the larger prey. In fact, season had more effect on diversifying the diet than did size of the lizards' trophic structures (i.e., mouths) or any possible feeding preferences. Niche overlap indices for prey length (0.86-0.94) and prey taxa (0.82-0.93) among all age-sex classes ran higher than those reported for a mainland anole with almost no sexual size dimorphism. Comparison of variables between the seasons (dry-Nov.-Mar., wet-AprilOct.) showed that lizards tended to ingest about the same volume of food (approx. 17 mm3 of food/g of lizard body wt). However, lizards ate more, but smaller prey in the dry season and fewer, but larger prey in the wet season. Relative fat body and liver weights were highest in the dry season and lowest in the wet season. Adult males and especially adult females experienced the greatest weight loss in these energy reserve organs; this was attributed in part to breeding activities. Coefficient of condition calculations (body wt/SVL) showed no body weight loss between seasons for any age-sex class of lizards. For the population, the volume of food taken across seasons appeared sufficient to increase energy reserves during the dry season and maintain body weight during the wet season.

Nutrient Reserves in Seeds of Selected Proteaceous Species From South-Western Australia.

Seed reserves of eight species of Proteaceae from south-western Australia were examined by chemical analysis, microscopy and scanning X-ray microanalysis. Cotyledons were the principal reserve organs of all species. Seeds had 30-500 times the level of P, 8-100 times the level of N, Cu and Zn and, on most species, higher levels of Mg, K, Mn and S than leaves or woody parts of fruits. Levels of Ca, Fe, Na and Cl in leaves and fruit parts were the same as or higher than those in seeds. The K:Ca ratios of seeds were very low (1:2). Seeds had only 1-16% of total fruit dry matter but contained 83-98% of a fruit's P, 43-78% of its N and much of its Zn, Mn and Cu. Seeds had no more than 3% of a fruit's Na or Cl. Oil (14-31%) and protein (15-64%) were major organic reserves of seeds; starch was absent. Protein bodies occurred at high density throughout the parenchyma of cotyledons of all species, and in epidermal and provascular tissues of some species. Globoids occurred in some protein bodies; crystalloids were absent. Globoid-containing protein bodies were confined to central mesophyll layers of cotyledons of Hakea spp. and Grevillea annulifera, to subepidermal parenchyma of Banksia spp. and Xylomelum angustifolium, but occurred in most cotyledonary tissues of Grevillea leucopteris; X-ray microanalysis of cotyledon tissues suggested that the globoids were rich in P, Ca, S and Mg, and in some species also in Fe, Zn and K. The species of Proteaceae investigated were considered to be very effective in channelling essential nutrients to their seeds.

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.

Occurrence of ethanol in pea plants in the course of growth under normal and anaerobic conditions

1) At a so-called natural anaerobiosis during the first 48 hours of germination the concentration of ethanol in pea tissues increases (according to the cultivation conditions) up to 40 μmol per gram fresh weight. 2) In a nitrogen atmosphere the content of ethanol in pea seedlings increases as well, and after a 90 hour incubation in N2 it can reach even 100 μmol ethanol per gram fresh weight. In older plants the content increases the most markedly in cotyledons, but considerable amounts were revealed also in stems and roots. Its increase in vegetative organs of plants cultivated both in light and darkness is more or less identical. Ethylalcohol can be formed by the vegetative organs themselves, as proved by the increase of this metabolite in plants deprived of reserve organs; in addition, however, it is evidently transported into them from reserve parts. Ethanol formed under anaerobiosis is catabolyzed after transferring plants to the air.

Osmotic Pressure in Roots and in Leaves in Relation to Habitat Moisture

Various investigators have demonstrated the importance of osmotic pressure as a factor regulating the passage of water from cell to cell and its absorption from the soil. The fact that young leaves retain their freshness for a longer period of time than older ones has been explained by Pringsheim (10), for wilting succulents, as the result of the more intense osmotic pressure of younger leaves. Moreover he has found more concentrated cell-sap in developing buds than in reserve organs like bulbs and tubers which are able to produce shoots without any extraneous water supply. According to this author's view, not only the earlier wilting but also the complete drying of adult parts of plants may be explained by the comparatively low osmotic pressure in these parts. But it is hardly possible to explain exclusively by reduced osmotic pressure the complete drying of plants; this phenomenon may be connected with some secondary factors invoked by the wilting, which leads to the death of tissues. The cells with low sap concentrations will really show earlier wilting, but at the same time further concentration will take place and therefore arrest the loss of water; further loss of water is possible only in the case of simultaneous death of young as well as old organs, which apparently does not take place. Renner (11), who investigated the absorption of water by shoots, found that there may be developed within plants an absorbing power reaching 10-20 atmospheres of negative pressure. This power has been related by Nathanson (9) to the osmotic power of the leaf tissue, and.he has shown that its intensity may be expressed by the diflerence of the osmotic pressure in the roots and in the leaves. Hannig (4) made a number of determinations for the roots and leaves of xerophytes, mesophytes, hygrophytes and floating and submerged hydrophytes and expected to find the greatest difference in the former and the smallest in the latter; but the results he obtained, as summarised in Table I, show that the percentage of species showing equality