A prestaining method for the quantitative assay of proteins on polyacrylamide gels

Dyes have been synthesised¹, which make it possible to prestain proteins prior to electrophoresis on polyacrylamide gels. After discussing the criteria which have to be fulfilled by the dyes, their method of application is described. The method has been tested on a number of selected acidic and basic proteins and also on peptide obtained by the digestion of bovine serum albumin with cyanogen bromide. Excellent reproducibility, stoichiometry and a sensitivity of 0.2 μg with some proteins has been obtained.     

Alteration of liver plasma membrane protein conformation by bovine growth hormone in vitro

The response of liver plasma membranes prepared from hypophysectomized, bovine growth hormone-treated hypophysectomized, and normal rats to addition of bovine growth hormone in vitro were studied by circular dichroism and spectrofluorometry. Membranes of hypophysectomized but not normal or treated rats showed increased negative ellipticity in the presence of bovine growth hormone (10^?9) without any change in trough position; at higher concentrations (10^?7?10^?6, m) there was less negative ellipticity. Membranes of hypophysectomized, normal, and growth hormone-treated rats all showed decreased emission of fluorescence and a small shift of the emission peak from 333 to 338 nm in the presence of bovine growth hormone (10^?17?10^?7, m). The excitation of fluorescence was quenched by bovine growth hormone. Polarization of excitation of fluorescence was unchanged.     

Effect of a bifunctional imidoester on dissociation of 70S ribosomes in Escherichia coli

Treatment of the 70S ribosome from $\text{Escherichia coli}$ with diethyl malonimidate dihydrochloride, a bifunctional imidoester, was found to result in the formation of crosslinkage between the two subunits. The 70S complex thus obtained no longer dissociates into 50S and 30S particles at 0.5mM Mg²⁺ concentration, but do so at lower concentrations (0.1mM), suggesting the release of protein(s) involved in the inter-particle cross-linkage from one or both ribosomal subunits.     

Biochemistry of mosquito infection: Preliminary studies of biochemical change in Culex pipiens quinquefasciatus following infection with Lagenidium giganteum

The effect of infection of larvae of the mosquito Culex pipiens quinquefasciatus by the fungus Lagenidium giganteum has been studied from a biochemical standpoint. Methods were developed to analyze larval extracts that were essentially free of parasitic material. Biochemical parameters investigated on a per larva basis were protein, and the enzymes o-diphenol oxidase, glutamate transaminase, alkaline phosphatase, trehalase, and chitobiase. The behavior of the total amino acid and sugar pools were also examined. In general it was found that the infected larvae exhibited a significant decrease in rate of synthesis of most of the parameters studied and that the rates eventually fell to zero when compared to healthy control organisms. The progress of mycosis was correlated with visual evidence and it was concluded that the larvae were dying from starvation as a consequence of the utilization of their endogenous reserves by the parasite. Death of the larvae occurred as a general rule, in laboratory conditions, some 48 hr after initiation of infection by the fungus.     

The ontogeny of maternal responsiveness in female Rockland-Swiss albino mice

Twenty-two-day-old female Rockland-Swiss albino mice ignored 1-day-old young. As age increased there was a decrease in the percentage of animals that ignored pups. Pup-killing, exhibited by a significant number of 32- and 42-day olds, declined as age increased. Furthermore, the number of females exhibiting maternal behavior increased with advancing age. Olfactory bulb removal and testosterone propionate treatment, each of which elicit pup-killing in adult females, did not induce killing behavior in 22-day olds. Finally, ovariectomy performed on Day 18 reduced the number of animals that displayed maternal behavior on Day 62.     

The properties of trehalase from the mosquito-parasitizing water mold, Lagenidum sp

The soluble trehalase from the phycomycete Lagenidium sp., a parasite of many species of mosquitoes, was purified by acid titration, acetone precipitation, and Sephadex G-200 chromatography to give a 170-fold increase in specific activity over the crude extract. The enzyme was specific for trehalose. A β-glucosidase was copurified with the trehalase, but did not interfere with its characterization. Lagendium trehalase had a K_m of 1.43 mm, and E_a of 11.4 kcal/mole, and a pH of optimum activity of 5.5–6.5, and a molecular weight of 72,000. It was denatured by 30 min incubation at temperatures above 50°C, severely inhibited by heavy metals, and competitively inhibited by sucrose. No other reported inhibitors, including mannitol and ATP, were effective. Suggested physiological roles for the enzyme include the breakdown of stored trehalose in the mycelium and zoospores, and the digestion of hemolymph trehalose in infected mosquito larvae.