Volume 98, Issue 1
January 1989, pages 1-76
pp 1-13 January 1989
The ‘S’ shaped duplex gland, the shortest among the male reproductive glands, ultrastructurally exhibits only a single cell type, characterized by the presence of multishaped rough endoplasmic reticulum, polymorphic Golgi bodies and vesicles. The frequent mode of secretion appears apocrine, with occasional merocrine and holocrine. Continuous with the height of secretory activity, the epithelia degenerates leaving only basement membrane and muscle layers.
pp 15-25 January 1989
Concurrent occurrence of holocrine type-degeneration along with high reproductive function in the secretory epithelia of the duplex of two Noctuid species,Spodoptera litura (F) andHeliothis armigera (H) (Lepidoptera: Noctuidae)
Ductus ejaculatorius duplex is the major sperm storage organ in male reproductive tract of Noctuid species. Although seminal vesicles and duplex are functionally sperm storage organs, duplex plays an important role in sperm functions on its transport from male to female. At the zenith of the reproductive function, duplex exhibits holocrine type-degeneration (secretion) concurrent with the height of secretory activity wherein the duplex secretion facilitates the transport of the spermatozoa into the female via spermatophore and contributes rich materials for spermatozoa maturity and physiological activity.
pp 27-33 January 1989
Effects of refrigeration (5±1°C) of newly hatched silkworm larvae on survival rate, growth and egg production were studied in two multivoltine races, Pure Mysore and Hosa Mysore. When refrigerated for 10 days, moth emergence (males: 83·3% vs 89·4% and females: 92% vs 90·2%) and fecundity (465·5 vs 458·3) did not differ significantly from the control. Reductions in cocoon weight by 4% (1·323 g vs 1·271 g) and 10·7% (1·323 g vs 1·181 g) were caused by 5 and 10 days of refrigeration. Marked increase in early stage (I and II instar), loss of larvae (12·9% vs 48·8%), decrease in effective rate of rearing (77·1% vs 33·5%), pupation rate (92·4% vs 65%) and reproductive rate (137·7 vs 36·9) were observed, when refrigerated for 10 days. Results on reproductive rate indicated one day’s refrigeration as safe period in Hosa Mysore but not in Pure Mysore. In December season, both races showed higher tolerance and possibility of safe refrigeration upto 2 days.
pp 35-39 January 1989
In vitro studies on uptake, storage and disappearance of norepinephrine were conducted on spleen slices of chicken. Uptake process was found to be time and concentration dependent. Maximum uptake of norepinephrine occurred at 10−4 M concentration after 45 min of incubation. Cocaine, metanephrine, phenoxybenzamine and a-combination of cocaine and metanephrine, all inhibited the accumulation of norepinephrine, the last being most effective, indicating that both uptake, and uptake, processes are operative simultaneously and independently in disposition of amine. Disappearance studies following maximum accumulation indicated that the release was monophasic from a single pool. Reserpine pretreatment significantly reduced the accumulation and enhanced the release of norepinephrine.
pp 41-49 January 1989
The gonadotropic function of the neurosecretory system of brain and thoracic ganglion in the adult female crab,Potamon koolooense is examined. The type A-cells of brain and thoracic ganglion display marked annual cyclic changes of synthesis and release of cytoplasmic material in association with the ovarian cycle. Administration of the thoracic ganglion extract during early oogenesis induced oocyte growth and precocious vitellogenesis, with an increase in the ovarian weight or gonad index and oocyte diameter. However, the brain extract injection did not produce marked changes in the immature ovary. The results suggest that the ovarian activity, particularly growth and vitellogenesis, depend on the neurosecretion of the thoracic ganglion, especially on the activity of A-cells. The neurosecretion of A-cells of the brain seems to be involved in the process of mating and ovulation.
pp 51-55 January 1989
Endosulfan, a chlorinated hydrocarbon insecticide was tested against the fishOreochromis mossambicus. The median lethal concentrations for 24, 48, 72 and 96 h were 0·02, 0·012, 0·007 and 0·006 ppm respectively. The fish were exposed to sublethal concentrations for about 10 days and the protein, carbohydrate and lipid contents in the liver tissue during this period was estimated. There is a general decline in the level of protein, carbohydrate and lipid which is due to the increasing length of exposure to endosulfan.
pp 57-64 January 1989
Croton bonplandianum invites a set of ant species to its extrafloral nectaries. The composition and frequency of these nectariferous ants on the plant were distinctly different from those on the ground. We have investigated the factors that govern visitation pattern of the ant species to the plant.
The available pattern of nectar, and the age-related increase in the nectar content influence the ant visitation. Availability of nectar in small dispersed units specifically encourages the visits of individual foragers and discourages the group foragers. Increase in the nectar content of the plant with aging, favours the host occupation by the nomadic ants,Tapinoma melanocephalum F. A few species such asPheidole woodmasoni Forel could not harvest the nectar in the plant due to their inability to climb. Differences in the habitat preferences of ants affect their composition on the host plants.
pp 65-76 January 1989
The dreissenid musselMytilopsis sallei (Recluz) settles on man made structures in confined harbour waters. The mussel unlike some mytilids is never found to have settled on coastal sea bed. It shows a good capacity to produce a byssus apparatus and develops a new one every time it settles afresh. Younger mussels develop byssus apparatus at shorter intervals and therefore move more often. Adults are relatively passive. Byssal thread development is influenced by the environmental factors and also by the quality of surface. The mussel achieves better adhesion on polar surfaces like slate and glass than on teflon. Tensile strength of adhesive threads is very poor as compared to other mytilids. This possibly is one of the reasons for its absence on sea beds where sea water turbulence is very high.