Vestured pits and vestured vessel member walls in some Indian dicotyledonous woods

NAIR, M. N. B. AND MOHAN RAM, H. Y., 1989. Vestured pits and vestured vessel member walls in some Indian dicotyledonous woods. The woods of 144 taxa belonging to 38 families of angiosperms were examined for vestured pits and vestured vessel member walls using scanning electron microscopy. Vestured pits are present in 66 taxa (belonging to ten families) and vestured vessel member walls occur in only six taxa (belonging to three families). In Ehretiaceae and Euphorbiaceae vestures are present only in certain vessel members. In Wrighlia tinctoria , perforation plates containing vestures have been observed in addition to the presence of vestured pits. A classification of vestured pits based on their morphology and distribution is proposed by us. In all the types of vestured pits, vestures are present on the margin of the outer pit aperture or on the pit chamber wall. Occasionally, they are present in the pit canal, on the margin and in the vicinity of the inner pit aperture and rarely over the inner walls of the vessel members. The functions of vestured pits are not clear, although several suggestions are made. Whether or not these structures affect wood processing is not presently understood. It appears that vestured pits and vestured vessel member walls have diagnostic rather than phylogenetic value.     

Nitrogen Metabolism of the Upper Three Leaf Blades of Wheat at Different Soil Nitrogen Levels

Upper three leaf blades on the mainshoot of wheat cultivar, cv. Pusa Lerma, grown under three soil nitrogen levels (0, 30 and 120 kg ha^-1), were examined for changes in total reduced nitrogen and protease activity at pH 4.0 and 7.0. No net loss of reduced nitrogen takes place prior to and around anthesis. The protease activity is low during this period. At later stages there is rise in the loss of nitrogen which is paralleled by enhancement in protease activity. From amongst the leaf blades, nitrogen concentration is significantly high in the flag and penultimate as compared to the values in the third leaf blade. There were significant differences in protease activity (pH 4.0) amongst the leaf blades. At pH 7.0, however, the differences between the flag and penultimate leaf blades were not significant. Highest enzyme activity was in the flag followed by penultimate and then third leaf blade. Soil N application significantly enhanced the nitrogen content of all the leaf blades. At pH 4.0, the protease activity (g fr. wt.^-1) increased significantly due to soil N application (N₃₀ over N₀). There was, however, decline in the enzyme activity at pH 7.0, though the differences at different soil N levels were not significant. Analysis in terms of μmol N (reduced form) accumulated in the grains (ear)^-1 revealed that two-thirds of N is translocated by 28-day stage and the rest between 28-day and final harvest. The three leaf blades together contributed 22.7, 32.6 and 48.5% of the grain N (ear)^-1 at N₀, N₃₀ and N₁₂₀- respectively. Most of the nitrogen applied to the soil is reduced by these leaf blades.     

Transfer and fate of male ejaculate in female Queensland fruit flies

Abstract Insect seminal fluid commonly comprises a complex cocktail of proteins and other biochemical components that migrate away from the female reproductive tract to sites elsewhere in the female body and elicit changes in female reproductive behaviour. The transfer of male seminal fluid molecules to reproductive and somatic tissues of the female Queensland fruit fly (‘Q‐fly’) Bactrocera tryoni is examined and some putative target sites identified. Male Q‐flies are fed a diet containing radiolabelled (³⁵S) amino acids, which are incorporated into male accessory gland products. Radioactivity diminishes within the accessory glands and increases in all assessed parts of the female body during copulation, indicating the transfer of these products into the female soma via the reproductive tract. There are significant changes in the absolute and proportional radioactivity profiles among female tissues over the next 22 h, with substantial reductions in the thorax and increases in the head. This is consistent with accumulation of behaviour‐modifying male products at binding sites in the female head. Parallels can be drawn between the data in the present study and seminal fluid distribution profiles and receptor binding documented in other insects.     

Restoration options for potential persistence of submersed aquatic vegetation: combining ecological, hydrodynamic and sediment transport modelling

1. Restoration of shallow turbid lakes to promote growth of submersed aquatic vegetation (SAV) requires knowledge of the environmental factors affecting SAV growth and persistence, and a means to predict the success of SAV reestablishment under different management scenarios to improve these environmental conditions. We used a dynamic ecological modelling approach relating SAV responses to changes in physical and chemical conditions, with information on water level, flow and transparency being provided by hydrodynamic and sediment transport models. 2. The potential persistence of Vallisneria americana was similar under simulated environmental conditions in 1946 and in 1954, as was the potential persistence of Potamogeton pectinatus, indicating that the disappearance of V. americana from Peoria Lake (U.S.A.) previously attributed to an extended spring flood in 1954, may have been related to the combined effects of changes in water level, flow and water transparency as well as possibly other factors. 3. Recent environmental conditions (for 2000) proved not to be conducive for the colonization and persistence potential of V. americana, but would allow colonization by P. pectinatus. The construction of a hypothetical levee along the eastern descending line of the navigation channel in Upper Peoria Lake, which was expected to reduce fetch‐ and navigation‐related turbidity, did not improve the situation for V. americana and overall deteriorated the situation for P. pectinatus. Thus, such a hydraulic alteration, generally considered as beneficial for SAV restoration, may not always be successful. 4. The results of the simulations indicated that the environmental conditions for potential persistence in Peoria Lake were generally less favourable for V. americana than for P. pectinatus. Measures suggested to restore SAV communities in such a lake should aim at reducing concentrations of total suspended solids at the point of inflow by a factor of three to four and limiting fetch‐ and navigation‐related resuspension.     

Lipid metabolism of Pleurotus sajor caju

The biosynthesis of lipids in the mycelium and sporophore of Pleurotus sajor caju was studied. Whereas in the mycelium the biosynthesis of lipids was directly primarily towards storage (e.g. tri-acylglycerols), in the sporophore it was directed towards structural components (e.g. sterols). The incorporation of ¹⁴C precursors into non-polar and polar lipid fractions was generally similar for ¹⁴C acetate, ¹⁴C palmitate, ¹⁴C oleate and ¹⁴C linoleate in the case of mycelium and sporophore. It appears that linoleic acid was utilised as a source of acetate for lipid biosynthesis in the sporophore. A significantly higher incorporation of label was seen in sporophore sterol than in mycelial sterol. Malate dehydrogenase activity increased in the mycelium grown in the presence of lipids. Lipase of P. sajor caju was inducive. The growth of P. sajor caju was enhanced by increased lipid utilisation. The implications of these results on commercial cultivation of this fungus are discussed.