Volume 58, Issue 1
July 1963, pages 1-63
pp 1-10 July 1963
1. A quantitative chromatographic analysis of the free and bound aminoacids of warm-(36° C.) and cold-(20° C.) acclimated earthworms (Lampito mauritii) was carried out.
2. Cold acclimation resulted in a decrease in the free amino acids and increase in the bound amino acids, while warm acclimation resulted in an increase in free amino acids and decrease in bound amino acids.
3. It is suggested that there is increased protein synthetic activity in cold acclimation. The turnover of proteins by catabolic release of bound amino acids and resynthesis is envisaged to result in changes in enzyme systems. The patterns of protein turnover appear to be different in cold- and warm-acclimated worms.
4. Changes observed in the individual amino acids like lysine, arginine, aspartic acid, glutamic acid and the phenolic amino acids are discussed in the light of our present knowledge on amino acid metabolism.
pp 11-13 July 1963
There is an increase in the nucleic acid phosphorus in the tissues of cold acclimated individuals as compared to normal mussels. This increase is greatest in the hepatopancreas (82% over normal) and less in the ctenidium (22·2%) and the foot (15·6%). It is suggested that this increase in the nucleic acid during acclimation to low temperature is associated with increased protein synthesis.
pp 14-18 July 1963
Physiology of low temperature acclimation in tropical poikilotherms - V. Changes in the activity of neurosecretory cells in the earthworm,Lampito mauritii, and evidence for a humoral agent influencing metabolism
Acclimation of the earthworm,Lampito mauritii, to low temperature (19° C.) results in increased activity of the neurosecretory cells in the brain. Addition of body fluids of cold-acclimated worms to the perfusion fluid causes increased (25%) oxygen consumption of normal worm (29° C.) tissues as well as warm (35° C.) acclimated worm tissues.
The results are discussed and it is suggested that the physiological changes resulting in acclimation to low temperature are triggered by the neurosecretory release of one or more humoral agents which cause systemic changes and induce increased synthesis of enzyme proteins and perhaps also directly act on tissues to raise their metabolic level. Attention is drawn to the similarity of the sequence of events occurring in connection with moulting in insects.
pp 19-27 July 1963
The qualitative and quantitative aspects of the proteins of the silkworm blood were studied by the technique of agarophoresis. The blood of larvae at the final stage revealed the presence of six different protein zones. Considerable differences in the patterns were observed at different stages of growth. There was an increase in the total nitrogen of the blood up to the 5th instar and then came a sudden decrease in the one-day old pupae. Nitrogen concentration was at its highest in egg 1 stage and the electrophoretic pattern closely corresponded to the final larval pattern. Results indicate to the involvement of silk glands in the synthesis and breakdown of a protein designated as protein 5.
pp 28-35 July 1963
The taxonomic interest of sclereid types as an aid in the identifications of species ofMemecylon and the utility of sclereid morphology in the problems of synonymy in the systematic treatment ofMemecylon is considered in this paper.
pp 36-44 July 1963
pp 45-50 July 1963
The thick-walled lignified, pitted cells found in the stem and leaf ofAvicennia may be placed under the category of “Brachysclereids” or “stone-cells” of Tschrich (1885) and Foster (1949). These are transformed parenchyma cells in the stem, a hypodermal or mesophyll cell in the petiole and lamina of the leaf. They are formed by the “secondary sclerosis” of these parenchyma cells.
pp 51-56 July 1963
Interspecific crosses between the cultivatedA. hypogaea and a vegetatively propagated species were effected and the cytology of the hybrids was studied.
Details of meiosis in the wild species have been worked out. A number of phenomena in the nature of (i) extrusion, (ii) non-disjunction and (iii) delayed-separation bridges, were exhibited. The similarity of the genomes ofA. hypogaea with those of the seed-propagated and asexually multiplied wild species has been brought out. The probable evolutionary mechanisms concerned in the origin and differentiation of species have been indicated.
pp 57-63 July 1963
The morphology and ctyology of synthetic tetraploids resulting from the cross,A. hypogaea × (A. hypogaea × A. sp. A. 329) is described. These are genetically variable and revealed a low degree of meiotic lability. The probable origin of the tetraploids as well as the basis for the variability has been discussed. The role of allotriploids as an intermediate stage in the experimental gene transference from related diploid species to the tetraploids and in facilitating gene introgression in nature has been indicated. Xenia is suggested as a possible explanation for the variation in the pod characters of crossed plants and hybrids.