Mating-induced loss of sex pheromone and sexual receptivity in insects with emphasis on Helicoverpa zea and Lymantria dispar

Mating in most species of insects leads to a transient or permanent loss in sexual receptivity of the females. Among moths, this loss of receptivity is often accompanied with a loss of the sex pheromone in the absence of calling, which also could be temporary or permanent. Most of the earlier work on changes in reproductive behavior after mating was done with Diptera in which sperm and/or male accessory gland secretions were shown to be responsible for termination of receptivity. In the corn earworm moth, Helicoverpa zea, mated females become depleted of pheromone and become nonreceptive to further mating attempts, but only for the remainder of the night of mating. A pheromonostatic peptide isolated from the accessory glands of males may be responsible for the depletion of pheromone, while the termination of receptivity is independently controlled. In the gypsy moth, Lymantria dispar, the changes in behavior following mating are permanent. In this species, the switch from virgin to mated behavior involves three steps: a physical stimulation associated with mating, transfer of viable sperm to the spermatheca, and commencement of oviposition. Signals generated by these factors operate through neural pathways and, unlike in H. zea, accessory gland factors seem not to be involved. © 1994 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Substrate specificities of lipases in view of kinetic resolution of unsaturated fatty acids

Several commercially available lipases have been evaluated with regard to their substrate specificity in the esterification of fatty acids having specific positions of cis double bonds, e.g. petroselinic acid (n-12 18:1), alpha-linolenic acid (n-3 18:3), gamma-linolenic acid (n-6 18:3), stearidonic acid (n-3 18:4), dihomogamma-linolenic acid (n-6 20:3), eicosapentaenoic acid (n-3 20:5) and docosahexaenoic acid (n-3 22:6), with n-butanol. A common feature of most lipases, e.g. those from Penicillium cyclopium, Candida cylindracea, Mucor miehei, Rhizopus arrhizus and Penicillium sp. is that fatty acids having the first double bond from the carboxyl end as a cis-4 (n-3 22:6), cis-6 (n-12 18:1, n-6 18:3, n-3 18:4) or a cis-8 (n-6 20:3) double bond are strongly discriminated against compared to the other fatty acids, such as myristic acid (14:0), the reference standard, and n-3 18:3. In the case of the lipase from porcine pancreas, however, the discrimination against the above fatty acids is not as strong as with the other lipases. In contrast, the lipase from Chromobacterium viscosum shows a preference for n-12 18:1, n-6 18:3 and n-3 18:4. The observed substrate specificities can be utilized for enrichment of particular fatty acids by lipase-catalysed kinetic resolution from fatty acid mixtures, derived from naturally occurring fats and other lipids.Dedicated to Prof. David A. Walker, Robert Hill Institute, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK, on the occasion of his sixty-fifth birthday on 18 August 1993 Correspondence to: K. D. Mukherjee     

Effect of time delay in specific growth rate on the periodic operation of bioreactors with input multiplicities

The effect of time delay in specific growth rate () on the periodic operation of bioreactors with input multiplicities is theoretically analyzed for productivity improvement. A periodic rectangular pulse is applied either in feed substrate concentration (S_f) or in dilution rate (D). Periodic operation under feed substrate concentration cycling gives improvement in productivity at lower value of ¯S_f of the two steady-state multiplicities of S_f only when the time delay in is larger. Whereas the larger value of ¯S_f gives improvement in average productivity for all values of time delay. Dilution rate (D) cycling gives an improvement in average productivity particularly for larger time delay in . This improvement in average productivity is obtained only at smaller value of dilution rate out of the two steady-state input multiplicities of D.List of Symbols D 1/h dilution rate - F memory function - g dummy variable - K_i g/l substrate inhibition constant - K_m g/l substrate saturation constant - P g/l product concentration - P_m g/l product saturation constant - Q g/(hl) product cell produced per unit time - S g/l substrate concentration - S_f g/l feed substrate concentration - S_f,p g/l feed substrate concentration during fraction of a period - X g/l biomass concentration - Y_X/S g/g cell mass yield - w variable either S or Z - Z g/l weighted average of substrate concentration Greek Letters 1/h time delay parameter - ₁ , ₂ product yield parameters, g/g and 1/h - pulse width expressed as a fraction of a period - 1/h specific growth rate - _m 1/h maximum specific growth rate - h period of oscillation - – average value     

Dissolution of sulphur particles by Thiobacillus ferrooxidans: substrate for unattached cells

The growth of Thiobacillus ferrooxidans on sulphur is known to proceed through the attachment of cells to the sulphur particles. Experiments, However, show that the cells in the liquid phase, which are not attached to the sulphur particles, also grow. It has been shown through the use of a two-compartment membrane reactor that this increase is partially due to the release of ions, corresponding to partially oxidized of sulphur, into the solution by the attached cells. The main soluble ion has been found to the thiosulphate, but traces of sulphite have also been detected. (c) 1993 John Wiley & Sons, Inc.     

Pentosan polysulfate,a potent anti HIV and anti tumor agent,inhibits protein serine/threonine and tyrosine kinases

The effect of nicotinamide-adenine dinucleotides (NAD⁺ and NADP⁺) on Ca²⁺ transport in rat liver nuclei was investigated. Ca²⁺ uptake and release were determined with a Ca²⁺ electrode. Ca²⁺ uptake was dependent on adenosine triphosphate (ATP; 2mM). The presence of NAD⁺ (2mM) or NADP⁺ (1 and 2mM) caused a significant inhibition of Ca²⁺ uptake following addition of 2mM ATP. Ca²⁺, which accumulated in the nuclei during 6 min after ATP addition, was significantly released by the addition of NAD⁺ (0.5–2mM) or NADP⁺ (0.1–2mM). However, the effect of NADH (2mM) or NADPH (2mM) on Ca²⁺ uptake and release clearly weakened in comparison with the effects of NAD⁺ and NADP⁺. Meanwhile, ryanodine (10M), thapsigargin (10M) or oxalate (0.5mM) had no effect on Ca²⁺ uptake and release in rat liver nuclei. These reagents did not significantly alter the effects of 2mM NAD⁺ on Ca²⁺ uptake and release. Thus, NAD⁺ and NADP⁺ had a potent effect on Ca²⁺ transport in rat liver nuclei. The present findings suggest that the liver cytosolic NAD⁺ (NADP⁺) is a factor in the regulation of the nuclear Ca²⁺ concentration. (Mol Cell Biochem121: 127–133, 1993)     

The effects of terminal heterologies on gene targeting by insertion vectors in embryonic stem cells.

We have examined the effects of placing nonhomologous DNA on the ends of an insertion-type gene targeting vector. The presence of terminal heterologies was found to be compatible with insertion targeting, and the terminal heterologies were efficiently removed. Terminal heterologies reduced the frequency of gene targeting to variable extents. The degree of inhibition of targeting was dependent on the length and the position of the heterology: 2.1kb heterologous sequences were more inhibitory than shorter regions of heterology, and heterology placed on the end of the long (4.8kb) arm of homology was more inhibitory than heterology positioned on the end of the short (0.8kb) arm. When heterology was placed on both arms of the targeting vector the targeting efficiencies were similar to or higher than when heterology was present on the long arm only. These results suggest that terminal sequences are removed simultaneously from both ends of targeting vectors. The removal of terminal sequences probably occurs by exonucleolytic degradation of both strands at each end, and removal of at least one of the strands is intimately coupled with the process of homologous recombination. These findings have implications for the design of gene targeting vectors.     

Self-cleavage activity of the genomic HDV ribozyme in the presence of various divalent metal ions.

To identify the divalent metal ions that can support the self-cleavage activity of the genomic ribozyme of human hepatitis delta virus (HDV), we tested the activity of various divalent metal ions in the ribozyme reactions catalyzed by HDV88 (683-770 nt) and 88DI3 (HDV88 with the sequence from 740-752 nt deleted). Among various metal ions tested, Mg2+, Mn2+, Ca2+ and Sr2+ efficiently supported the self-cleavage reactions of the HDV88 and 88DI3 ribozymes. In the case of the 88DI3 ribozyme, other divalent metal ions, such as Cd2+, Ba2+, Co2+, Pb2+ and Zn2+, were also able to support the self-cleavage reaction to some extent (< 10%). In the presence of spermidine (0.5 mM), the cleavage reaction was promoted at lower concentrations of effective divalent metal ions. The HDV ribozyme represents the only example of ribozyme to date of a ribozyme that catalyzes the self-cleavage reaction in the presence of Ca2+ ions as efficiently as it does in the presence of Mg2+ ions.     

Identification of a UDP-glucosyltransferase conferring deoxynivalenol resistance in Aegilops tauschii and wheat

Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley.     

Crystallographic,morphological and photoluminescent investigations of Tb3+-doped YAlO3 perovskites for lighting applications

Terbium(III)-doped yttrium aluminate perovskite (YAP:xTb³⁺) (x = 0.01–0.08 mol) was synthesized using a simple gel-combustion method. Structural elucidations were performed using X-ray diffraction (XRD) and Rietveld analysis. Fourier-transform infrared spectral studies validated the efficient synthesis of designed doped samples. Transmission electron microscopic images showed the agglomerated irregular dimensions of the synthesized nanocrystalline materials. When excited at 251 nm, a strong emissive line attributed to ⁵D₄ → ⁷F₅ electronic transition was observed at 545 nm (green emission). The maximum luminescence was found at the optimized concentration (0.05 mol) of Tb³⁺ ions; this emission was quenched by dipolar–dipolar (d–d) interactions. Chromaticity (x and y) and correlated colour temperature parameters were obtained by analysing the emission profiles. Finally, the colour coordinates of nanophosphors were closer to the National Television Standards Committee green coordinates, which replicates their potency in the design and architecture of R-G-B-based white LEDs.     

Noncytotoxic Dy3+-activated glass emits cool white light for near ultraviolet-based white light-emitting diodes,visible lasers,and biomedical applications

Using the melt quenching technique, a lithium zinc borate glass (LZB) system with trivalent dysprosium ions (Dy³⁺) was synthesized, and the luminescence and lasing properties of these materials were examined for the generation of white light. Structural investigation through X-ray diffraction revealed that the prepared glass had an amorphous nature. The optimized glass containing 0.5 Dy³⁺ had a direct optical band gap of 2.782 eV and an indirect optical band gap of 3.110 eV. A strong excitation band at 386 nm (⁶H_15/2→⁴I_13/2) was recognized in the ultraviolet (UV) light region of its excitation spectrum. Emission bands could be seen in the photoluminescence spectrum at 659, 573, and 480 nm under the 386 nm excitation. These transitions of emission resembled electronic transitions such as (⁴F_9/2→⁶H_11/2), (⁴F_9/2→⁶H_13/2), and (⁴F_9/2→⁶H_15/2). In a pristine glass matrix, the higher intensity ratio of yellow to blue can result in the production of white light. The optimized Dy³⁺ ion concentration was observed to be 0.5 mol%. In addition, an analysis of lifetime decay was conducted for all synthesized glasses, and their decay trends were systematically investigated. Noticeably, we assessed the photometric parameters and found that they were close to the white light standard. Furthermore, a cytotoxicity study was carried out using lung fibroblast (WI-38) cell lines for the optimized 0.5Dy³⁺-doped LZB glass and it appeared to be noncytotoxic. It is clear from the results that the noncytotoxic LZB glass doped with 0.5 Dy³⁺ ions could be a suggestive choice for the manufacture of white light-emitting diodes and lasers using near-UVs.