Effect of continuous application of manures and fertilizers on rhizosphere microflora in arecanut palm

Summary The rhizosphere microflora of arecanut palm under continuous application of organic manures and inorganic fertilizers was studied. The nutrients applied are 100 g N, 40 g P₂O₅ and 140 g K₂O/palm/year in the form of organics and inorganics. The application of organic manure increased the microbial population. The increase in microbial population was observed between the rhizosphere samples collected at 0–30cm and 30–60 cm depths. The surface cultivation of soil increased the microbial population.Trichoderma sp. andAspergillus sp. dominated in therhizosphere of arecanut palm. Contribution No. 208. Central Plantation Crops Research Institute, Vittal-574243, Karnataka, India.     

Effect of polymyxins on the lipopolysaccharide-defective mutants of Proteus mirabilis

The effects of polymyxins (Pmx) B and E on smooth and rough Proteus mirabilis strains were investigated. P. mirabilis mutant R4/028 which completely lacked 4-amino-4-deoxy-L-arabinose was sensitive towards both polymyxins, and the other P. mirabilis strains investigated were resistant. Lipopolysaccharide (LPS) from Pmx-sensitive R4/028 strain, binds 50% more Pmx B than LPS derived from resistant P. mirabilis strains. The presence of iodoacetamide, N-ethylmaleimide and chloramphenicol rendered the Pmx-resistant P. mirabilis strains sensitive towards both polymyxins.     

Altered flower/fruit clusters of the kitul palm used as roosts by the short-nosed fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae)

The short-nosed fruit bat (Cynopterus sphinx) creates bell-shaped cavities in flower/fruit clusters of the kitul palm (Caryota urens) by chewing and severing flower and fruit strings. These cavities (stem tents) in which the bats roost are usually about one metre deep and 30 cm in diameter. We observed groups of bats roosting in fully-formed stem tents during the daytime, and the construction and subsequent occupancy of newly formed tent cavities. Stem tents are similar in principle to leaf tents except, instead of being formed when bats chew veins and the surrounding tissues of leaves, stem tents are formed in C. urens when bats completely cut several of the central flower/fruit strings. Flower/fruit strings are mostly severed when they are in an immature stage, at times when they are thin and widely spaced. Once these strings thicken and become heavily-laden with mature fruits, bats cannot penetrate the cluster to sever them. Our observations suggest that a single male enters an immature flower or fruit cluster either from below or the sides and severs the central strings along the peduncle. In early phases of stem-tent construction, C. sphinx severs flower/fruit strings at a rate of about one or two per day, and cluster alteration may continue upwards to two months. Only one immature flower/fruit cluster on a C. urens tree is available for alteration by bats at any given time. That this bat does not roost in the fruit/flower cluster during the day, when a tent is under construction, and the accumulation of chewed flower and fruit strings beneath such a cluster in the morning, suggests that tent construction by C. sphinx is a night-time activity.     

Physiological responses of mules on prolonged exposure to high altitude (3 650 m)

Eight healthy male animals were inducted and kept for 2 1/2 years at 3 650 m altitude and subjected to normal work schedules. Physiological measurements viz. heart rate, blood pressure, minute ventilation, oxygen consumption, respiration rate, hemoglobin, packed cell haematocrit volume and eosinophil count were made on these animals at periodic intervals. On acute induction to an altitude of 3 650 m these animals demonstrated a sudden increase in tidal volume, a decrease in Rf and no change in V_E, suggesting a decreased dead space/tidal volume ratio at altitude.However, all these changes stabilised within 3 weeks but on prolongation of stay, the physical state of these animals was adversely affected. The respiratory adjustments occurring on return to sea level appear to be a response to thermal stress. The initial increase in heart rate and blood pressure stabilised by the 2nd week.     

Human ETS1 oncoprotein. Purification, isoforms, -SH modification, and DNA sequence-specific binding.

The human ETS1 proto-oncogene proteins have been isolated from the T-cell leukemia line, CEM, by immunoaffinity chromatography and their identity confirmed by NH2-terminal amino acid sequencing. Incubation of CEM cells with N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) indicates that ETS proteins can be modified in their cellular context and that pretreatment of the cells with N-ethylmaleimide (NEM) protects ETS1 proteins from TLCK modification. These data show that ETS1 proteins can exist in at least two different states, -SH-available and -SH-protected. Renatured human ETS1 has DNA sequence-specific binding to the PEA3 (CAGGAAGT) motif. The ETS1.PEA3 complex can be observed by electrophoretic mobility shift assays (EMSA). Purified ETS1 retards a band which is exactly the same size as a complex that is retarded from nuclear extracts prepared from CEM cells. Reduced ETS1 is required to form the ETS1.PEA3 complex, however; modification of the ETS1 -SH groups by either NEM or by TLCk does not inhibit formation of the complex. The ETS1.PEA3 complex formed with TLCK-modified ETS1 has a slower mobility than the complex formed with unmodified ETS1. Zone sedimentation analysis of purified ETS1 indicates that it is the monomer of ETS1 which binds to the PEA3 oligonucleotide.     

A novel technique to overcome browning in tissue culture

Experiments conducted using Dioscorea alata L. revealed that an exudate from the cut end of the explants was responsible for browning of the culture medium. Browning did not affect growth of roots and shoots when explants were cultured in a large volume of medium, but in a small volume it was lethal. Sealing the cut ends with paraffin wax was found to control browning by preventing exudation. This simple technique permitted establishment of cultures in a small volume of medium in about 90 percent of the cases, while in unsealed cultures lethal browning was recorded in 80 percent of the cases. The advantages of this technique over other methods of controlling browning are discussed.     

Diffusion of phosphate to plant roots in soil

Summary A method is described for computing the theoretical distribution of solutes around a root with root hairs. The P concentration profile around the primary root of a rape seedling with root hairs, growing in a low-P soil, showed considerably greater depletions than predicted by this method, using the relationship between P in soil and in solution obtained from a desorption isotherm experiment. This suggests an enhanced release of soil P into solution in the rhizosphere.Soil Science Laboratory, Department of Agricultural Science, University of Oxford