The effect of larval nutrition on egg production in Rhodnius prolixus

Rhodnius prolixus adults which had fed to repletion at each larval instar were frequently autogenous, while those allowed to take only partial blood meals at the 3rd, 4th and 5th larval instars were always anautogenous.Bugs fed to repletion at each larval instar had large abdominal fat bodies throughout adult life. In such bugs, the quantity of blood associated with the production of one egg was small and constant during the course of several blood meals.Bugs fed partial blood meals as larvae had small abdominal fat bodies following ecdysis to the adult; the quantity of blood associated with the production of one egg was large following the first adult feed because some of the blood meal was used to increase the size of the abdominal fat bodies.     

An improved method for studying the condition of fish, with an example using Pacific sardine Sardinops sagax (Jenyns)

The statistical treatment of condition used in many previous studies has been to determine a predicted weight for a fish, and to calculate a ratio of actual to predicted weight. The ratios obtained, known as condition factor K , are then further analysed using analysis of variance or other techniques to relate changes in K to other independent variables. It is suggested that condition can be studied better by using a single model to analyse the response of fish weight to a number of factors simultaneously. This approach affords benefit from the simplicity of using an integrated analysis and avoids problems with skewed distributions of ratios. An example using data on the Pacific sardine, Sardinops sagax (Jenyns), is given. Changes in condition of this fish due to monthly, yearly and temperature effects are calculated.     

STEROLS OF DICTYOCHA FIBULA (CHRYSOPHYCEAE) AND OLISTHODISCUS LUTEUS (RAPHIDOPHYCEAE)1

Sterols from cultured Dictyocha fibula Ehrenberg and Olisthodiscus luteus Carter were extracted and identified for comparison with sterols from other Chromophycota species. Although orientation at C-24 was not absolutely determined, the sterols of Dictyocha, a silicoflagellale, appeared to consist of only 24-methyl-22-dehydrocholesterol and 24-methylenecholesterol, a sterol composition not known in any other alga. This is in keeping with the taxonomic isolation Dictyocha has among algae. On the other hand, Olisthodiscus luteus contained 24-ethylcholesterol, 24-ethylcholestanol, 24-methylcholesterol, and cholesterol. This composition is in accord with sterols of members of the Xanthophyceae and Raphidophyceae.     

Synthesis of viruslike particles by expression of the putative capsid protein of Leishmania RNA virus in a recombinant baculovirus expression system.

The putative capsid open reading frame (ORF2) of the Leishmania RNA virus LRV1-4 was expressed in a baculovirus expression system. The expressed protein was identified by Western immunoblot analysis with polyclonal antiserum raised to purified LRV1-4 virus. Electron microscopy and sedimentation analysis indicated that the expressed protein self-assembles into empty viruslike particles of similar size and shape to authentic virus particles, thus confirming that ORF2 encodes the viral capsid. The expressed particles are present exclusively in the cytoplasm of infected SF9 cells and are able to assemble in the absence of LRV1-4 RNA, viral polymerase, or any Leishmania host factors.     

Three CA/GT repeat polymorphisms from loci D21S414 and D21S1234 on human chromosome 21

We report three new polymorphic CA repeat microsatellites (ABM-21, ABM-C37A, and ABM-C37B) in two different loci (D21S414 and D21S1234), located in bands q21 and q11.2 of human chromosome 21 (HC21) and that were isolated from a HC21 phage library (LA21NS01). Heterozygosities for ABM-21, ABM-C37A, and ABM-C37B were 0.74, 0.50, and 0.67 respectively. These three CA repeat markers should be useful in the construction of a high resolution genetic map of this region of HC21.     

Association of a DNA marker with Hessian fly resistance gene H9 in wheat

The Hessian fly [Mayetiola destructor (Say)] is a major pest of wheat (Triticum aestivum L.) and genetic resistance has been used effectively over the past 30 years to protect wheat against serious damage by the fly. To-date, 25 Hessian fly resistance genes, designated H1 to H25, have been identified in wheat. With near-isogenic wheat lines differing for the presence of an individual Hessian fly resistance gene, in conjunction with random amplified polymorphic DNA (RAPD) analysis and denaturing gradient-gel electrophoresis (DGGE), we have identified a DNA marker associated with the H9 resistance gene. The H9 gene confers resistance against biotype L of the Hessian fly, the most virulent biotype. The RAPD marker cosegregates with resistance in a segregating F₂ population, remains associated with H9 resistance in a number of different T. aestivum and T. durum L. genetic backgrounds, and is readily detected by either DGGE or DNA gel-blot hybridization.Purdue University, Agric. Exp. Stn. Journal paper No. 14440     

Effects of membrane potential on just detectable movement in rat skeletal muscle: Effects of denervation

The potential, Vt, at which a brief test depolarization first elicited movement was determined using two-microelectrode point voltage clamp. We expected that inactivation of excitation-contraction coupling at conditioning potentials between ?60 and 0 mV would shift Vt to more positive potentials, and that fibers would become inactivatable with less conditioning depolarization in EDL than soleus. The curve relating Vt to conditioning potential had a negative slope (which was insensitive to addition of 1 mm cobalt or replacement of calcium with 20 mm CaEGTA) between ?60 and ?35 mV and a steep positive slope with further depolarization. Unexpectedly, fibers became inactivatable with less conditioning depolarization in soleus than in EDL when Vt was measured with 50 msec test pulses. However, the positive shift in Vt became less steep as test pulse duration lengthened in soleus fibers. When Vt obtained with test pulses approaching rheobase (10 msec in EDL and 500 msec in soleus) was compared, EDL fibers became inactive with less conditioning depolarization than soleus fibers. The increase in Vt became steeper with 1 mm cobalt or 20 mm CaEGTA and was shifted to more positive potentials by denervation in soleus fibers. We conclude that inactivation (i) does not strongly influence threshold contractions at conditioning potentials between ?60 and ?40 mV and (ii) influences Vt between ?40 and 0 mV in a manner that depends on test pulse duration.