Sexual differentiation in quail: Conversion of androgen to estrogen mediates testosterone-induced demasculinization of copulation but not other male characteristics

Previous research has shown that administration of either testosterone or estradiol to male quail embryos will demasculinize behavior and morphology. Six experiments in which embryos were treated were conducted to test the hypothesis that this testosterone-induced demasculinization is due to conversion of testosterone to estrogen (aromatization). In Experiment 1, dihydrotestosterone propionate, a nonaromatizable androgen, failed to demasculinize copulatory behavior, but did demasculinize crowing, strutting, and proctodeal glands. In Experiment 2, injection of the aromatizable androgens testosterone propionate (TP), testosterone, or androstenedione demasculinized copulatory behavior, the nonaromatizable androgen androsterone failed to have such an effect, and all androgens demasculinized proctodeal glands. In Experiment 3, Silastic implants of testosterone demasculinized all male characteristics, whereas implants of androsterone demasculinized only proctodeal glands. In Experiment 4, the antiestrogen tamoxifen prevented TP from demasculinizing copulatory behavior, but had no such effect with respect to crowing and strutting. In Experiments 5 and 6, the aromatization inhibitor 1,4,6-androstatrien-3,17-dione (ATD) prevented TP but not estradiol benzoate from demasculinizing copulatory behavior. Thus (1) in quail, testosterone-induced demasculinization of copulatory behavior is due to androgen aromatization, whereas testosterone-induced demasculinization of crowing, strutting, and proctodeal glands is not; (2) the distinct components of normal male reproductive behavior exhibit different patterns of steroid specificity during the organizational period, as was previously shown for the activational period; (3) the steroid specificity of crowing, strutting, and proctodeal glands changes between the organizational and activational periods. During organization, there is little specificity, whereas during activation, these characteristics respond only to androgens, never to estrogens. This difference suggests that developmental changes have occurred in the underlying biochemical substrates.     

Formation of heterophile antibodies by human tonsilar lymphocytes: II. In vitro stimulation with allogeneic cells

Short-term cultures of human tonsilar lymphocytes (HTL), 5 × 10⁶ cells/culture, in medium RPMI 1640 supplemented with human group AB serum were studied for the production of plaque-forming cells (PFC) against sheep (SRBC) and bovine (BRBC) red blood cells following in vitro stimulation by various allogeneic lymphoid cells. Of 55 HTL specimens examined, 48 produced a significant number (50–300/culture) of PFC against SRBC and/or BRBC following the in vitro stimulation. The optimal doses of the stimulator HTL and peripheral blood lymphocytes (PBL) were 10⁷ and 5 × 10⁶/culture, respectively. After the stimulation, PFC appeared in significant numbers on the third day, reached the peak number on the sixth day, and decreased sharply in number thereafter. Removal of E-rosetting cells from both stimulator and responder populations abolished the PFC formation. PFC formation against SRBC was inhibited by solubilized Forssman antigen, while PFC formation against BRBC was inhibited strongly by Hanganutziu-Deicher antigen, hardly by Paul-Bunnell antigen and not at all by Forssman antigen. Supernatants of mixed lymphocyte culture of PBL were shown to enhance PFC formation of HTL cultures stimulated by allogeneic lymphocytes. The results of this study indicated that in vivo primed B cells of the HTL were triggered in vitro by allogeneic stimulation for the heterophile antibody formation. Since these antibodies are apparently directed against Forssman and Hanganutziu-Deicher antigens, the “allo” nature of these antigens as well as their relationship to the previously described heterophile transplantation antigens have to be clarified.     

Schistosoma mansoni: Electrophoretic characterization of strains selected for different levels of infectivity to snails

Individual adult Schistosoma mansoni from strains selected for high or low infectivity to specific strains of the snail intermediate host, Biomphalaria glabrata, were subjected to enzyme electrophoresis on starch gels. Fourteen enzyme systems were analyzed in an attempt to find electrophoretic markers associated with genes for infectivity to snails. The S. mansoni strains were selected from different isolates from Puerto Rico in several strains of B. glabrata. Of an estimated 18 loci, 3 were polymorphic and the remainder monomorphic. For 1 of the 3 polymorphic enzyme loci, lactate dehydrogenase (Ldh, EC 1.1.1.27), phenotype frequencies were correlated with infectivity to snails. In schistosome strains of low infectivity, frequencies of the Ldh-N phenotype ranged between 0.56 and 0.69, while in strains of high infectivity, Ldh-N frequencies were typically 0.91 to 1.00. Whether the correlation is accidental or due to some form of association, such as chromosomal linkage, between the locus responsible for variation in lactate dehydrogenase and a gene for infectivity to snails remains to be determined.     

Mutagenic effect on L5178Y mouse lymphoma cells by growth in ethylene oxide-sterilized polycarbonate flasks

Summary The mutation frequency of L5178Y mouse lymphoma cells to resistance to 5′-bromo-2′-deoxyuridine increased 6-to 14-fold after growth in ethylene oxide-sterilized polycarbonate culture flasks compared to growth in glass flasks. No comparable increase was observed when L5178Y cells were growth in identical polycarbonate culture flasks sterilized by autoclaving.     

Estrogen-dependent trypsin-like activity in the rat uterus. Localization of activity in the 12,000g pellet and nucleus.

Direct evidence was obtained for the presence of hormone-stimulated trypsin-like protease activity in the rat uterus. Ovariectomized rats were either untreated (U), treated with estradiol (E), or estradiol plus progesterone (EP). The uteri were excised and subcellular fractions were prepared. Each fraction was assayed for protease activity using protamine as substrate, the cleavage products being quantitated fluorometrically following reaction with 4-phenylspiro[furan-2(3H),1′-phthalan]-3,3′dione (Fluram). Fractions from U rats yielded negative results, whereas the 12,000g pellets and nuclei from the uteri of E and EP rats exhibited appreciable activities. No significant increase in protease activity was observed in thymus and diaphragm following hormone treatment, indicating organ specificity. The enzyme (or enzymes) from the 12,000g pellet was solubilized and some characteristics were determined. The apparent K_m is about 1.0 × 10^?6m, the temperature optimum is about 44 °C and maximum velocity is achieved in the alkaline range (pH ~ 8.5). The protease is a plasminogen activator and is inhibited by diisopropyl fluorophosphate, Antipain, and Leupeptin. These properties resemble those of trypsin.     

Deuterium oxide effects on excitation-contraction coupling of skeletal muscle

²H₂O (99.8%) Ringer's solution greatly reduces the twitch and tetanus of frog sartorius muscle and, as specially shown here, slows the onset features of the mechanical output of the twitch by: (a) increasing the time (L_R) from stimulus to start of latency relaxation; (b) slowing the developmet of the latency relaxation, and (c) greatly decreasing the rate of onset of tension development. These changes reflect effects of ²H₂O on excitation-contraction coupling and they represent the critical direct effects of ²H₂O on muscle since it does not depress either the action potential or the intrinsic myofibrillar contractility. The increase in L_R is attributed to slowed inward electrical propagation in the T-tubule. But the critical effect of ²H₂O on frog muscle is to greatly depress mobilization of activator Ca²⁺. The depression of the Ca²⁺ mobilization and of its effects on the activation of contraction evidently result from (a) a lowered rate of release of Ca²⁺ from the sarcoplasmic reticulum, as indicated by the slowed development of the latency relaxation, (b) a decreased amount of Ca²⁺ released in a twitch, and (c) a reduced speed of diffusion of the Ca²⁺ to the contractile filaments. The depressed mobilization of Ca²⁺ is apparently the essential cause of ²H₂O's general depression of twitch and tetanus output.     

Delayed fluorescence from Rhodopseudomonas viridis following single flashes

Delayed fluorescence from Rhodopseudomonas viridis membrane fragments has been studied using a phosphoroscope employing single, short actinic flashes, under conditions of controlled redox potential and temperature. The emission spectrum shows that delayed fluorescence is emitted by the bulk, antenna bacteriochlorophyll. The energy for delayed fluorescence, however, must be stored in a reaction-center complex including the photooxidized form (P⁺) of the primary electron-donor (P) and the photoreduced form (X^?) of the primary electron-acceptor. This is shown by the following observations: (1) Delayed luminescence is quenched (a) at low redox potentials which allow cytochromes to reduce P⁺ rapidly after the flash, (b) at higher redox potentials which, by oxidizing P chemically, prevent the photochemical formation of P⁺X^?, and (c) upon transfer of an electron from X^? to a secondary acceptor, Y. (2) Under conditions that prevent the reduction of P⁺ by cytochromes and the oxidation of X^? by Y, the decay kinetics of delayed fluorescence are identical with those of P⁺X^?, as measured from optical absorbance changes.The main decay route for P⁺X^? under these conditions has a rate-constant of approximately 10³ s^?1. In contrast, a comparison of the intensities of delayed and prompt fluorescence indicates that the process in which P⁺X^? returns energy to the bulk bacteriochlorophyll has a rate-constant of 3.7 s^?1, at 295 °K and pH 7.8. The decay kinetics of P⁺X^? and delayed fluorescence change little with temperature, whereas the intensity of delayed fluorescence increases with increasing temperature, having an activation energy of 12.5 kcal · mol^?1. We conclude that the main decay route involves tunneling of an electron from X^? to P⁺, without the promotion of P to an excited state. Delayed fluorescence requires such a promotion, followed by transfer of energy to the bulk bacteriochlorophyll, and this combination of events is rare. The activation energy, taken with potentiometric data, indicates that the photochemical conversion of PX to P⁺X^? results in increases of both the energy and the entropy of the system, by 16.6 kcal · mol^?1 and 8.8 cal · mol^?1 · deg^?1. The intensity of delayed fluorescence depends strongly on the pH; the origin of this effect remains unclear.     

Inductive activity and enduring cellular constitution of a supernumerary apical ectodermal ridge grafted to the limb bud of the chick embryo.

Apical ectodermal ridges (AERs) isolated from 3- to 4-day chick and quail embryos were prepared by means of trypsinization and microdissection and then were grafted to the dorsal or ventral side of a host chick wing bud. They induced supernumerary limb outgrowths from the host bud showing, respectively, a bidorsal or biventral organization, as determined by the patterns of feather germs. The grafted ridge cells persisted, as revealed by histological sections of supernumerary chick limb parts growing under the influence of quail AERs, whose cells are readily distinguished after application of the Feulgen reagent.These results show that the AER induces limb outgrowth regardless of whether it is associated with dorsal or ventral limb ectoderm and that its continued existence is not dependent on contributions of ectodermal cells from the opposed ectodermal faces of the limb bud. The AER is pictured as maintaining the subjacent mesoderm in a condition of developmental plasticity without specifying its differentiation with respect to the proximodistal axis. It remains uncertain whether the positional values of cells that develop under the influence of the AER arise within these cells themselves or appear in response to influences from proximal sources.     

Kinetic studies on the diaqua form of cis-platin and various nucleobases

Kinetic studies on cis-[Pt(NH3)2(OH2)2]2+ and various nucleobases show that this ion reacts more quickly with guanosine than with adenosine, cytidine, and thymidine, and that a monophosphoric acid unit considerably enhances the rate of reaction of guanosine; the kinetic preference of 5'-GMP over 5'-AMP may point to a greater thermodynamic selectivity.     

Computer simulation of cellular movements: cell-sorting, cellular migration through a mass of cells and contact inhibition

The motility rules for cellular movement proposed earlier by Goel &; Rogers for engulfment of two or more intact embryonic tissues have been used to simulate on a computer the phenomena of cell-sorting, migration of individual cells through a mass of cells and contact inhibition of overlapping. These simulations in the most part are found to be consistent with the observations with real cells.