MEIOSIS IN THE OOMYCETES: I. A MICROSPECTROPHOTOMETRIC ANALYSIS OF NUCLEAR DEOXYRIBONUCLEIC ACID IN SAPROLEGNIA TERRESTRIS

A cytological and cytochemical examination of Saprolegnia terrestris Cookson was undertaken to resolve the conflict of opinion regarding the life cycle of fungi in the Saprolegniaceae, i.e., whether meiosis is zygotic or gametic. Microspectrophotometric analysis reveals that pre-divisional oogonial and antheridial nuclei are 4C; a subsequent reduction division in the sex organs produces 1C male and female gametes. These division products coexist in the developing oospore and presumably fuse to produce the diploid zygote. Analysis of the somatic hyphal nuclei shows a 2C DNA content, with the characteristic skew and bimodal character indicative of predominantly G1, and some S-period and G2 types. The evidence is completely consistent with gametic meiosis, i.e., a predominant diploid vegetative phase and short haploid phase, and refutes the notion of zygotic meiosis. Further ramifications of the work are discussed along with preliminary results of related work in progress.     

An Improved Diluent for Rubella Hemagglutination and Hemagglutination-Inhibition Tests

Rubella hemagglutinating (HA) antigen was prepared in BHK-21 tissue as 5% cell suspensions and from unconcentrated and 20× concentrated infected supernatant fluids. In some instances, unconcentrated fluids were treated with Tween 80 and ether; cell suspensions were treated with ether alone. Preparations were tested for HA activity in dextrose-gelatin-Veronal (DGV) buffer solutions; 0.85% NaCl; Sorenson's phosphate-buffered saline, pH 7.2; and a diluent of 0.9% NaCl, 0.1% CaCl₂ (anhydrous), and 0.1% MgSO₄·7H₂O. HA titers were consistently two- to fourfold higher in the saline with added Ca⁺⁺ and Mg⁺⁺ than in DGV. Hemagglutination-inhibition titers of paired human sera were the same in either diluent. It is suggested that the interaction between rubella HA antigen and the red cells of young (less than 1-day-old) chicks may be at least partially ion dependent and that titers are enhanced by increased quantities of divalent cations.     

Inhibitory Effects of Dichlorophenoxyacetones on Auxin-induced Growth of Avena Coleoptile Sections

Six dichlorophenoxyacetones were synthesized and examined as potential metabolic antagonists utilizing Avena coleoptile sections and the straight growth assay procedure. Supplements of indoleacetic acid promoted growth of the sections which were inhibited by the analogs; the most inhibitory derivatives were 2,3-; 2,4-; 2,5-; and 3,4-dichlorophenoxyacetone which produced half-maximal growth responses (relative to the unaug-mented control growth) at concentrations of 106, 86, 80, and 62 μg/ml, respectively. A Lineweaver-Burk plot of the data for the inhibition by 2,4-dichlorophenoxyacetone and its reversal by indoleacetic acid appeared to represent an uncompetitive-like inhibition.     

Structure/activity relationships in the arginine taste pathway of the channel catfish

To characterize the molecular/structural requirements for activationor antagonism of the arginine taste pathways in catfish, Ictaluruspunctatus, structure/activity studies were performed using integratedmultiunit responses and cross-adaptation. Of all the guanidinium-containingcompounds tested, only L-arginine, L--amino-ß-guanidinopropionic acid (L-AGPA) and L-arginine methyl and ethyl esterswere strong stimuli. Results of functional group substitutionsand modification of the L-arginine parent molecule indicatedthat: (i) stereospecificity was observed with D-arginine beinga much less effective stimulus than L-arginine; (ii) an L-aminogroup must be present and unblocked (-chloro-guanidino-N-valericacid and N-acetyl L-arginine were weak or inactive stimuli);(iii) a free carboxylic acid group was not necessary for activity;(iv) the distance between the anomeric carbon and the guanidiniumgroup was not critical (L-AGPA, having two methylene groupsless than L-arginine was a moderately strong stimulus as wasL-canavanine) and (v) modification or substitution of the guanidinumgroup by other basic groups including amine, methyl or dimethylamineor by an isosterc (ureido) resulted in loss of stimulatory ability.In general, those stimuli and analogs that were good cross-adaptersof L-arginine stimulation were also good competitors for L-[³H]argininebinding to a partial membrane fraction (P2) from catfish tasteepithelium. On the other hand, compounds that were poor cross-adaptingstimuli were also poor binding competitors. While D-argininewas a poor stimulus, it did cross-adapt L-arginine and competedwell with L-[³H]arginine for binding to fraction P2.     

A novel and remarkably thermostable ferredoxin from the hyperthermophilic archaebacterium Pyrococcus furiosus.

The archaebacterium Pyrococcus furiosus is a strict anaerobe that grows optimally at 100 degrees C by a fermentative-type metabolism in which H2 and CO2 are the only detectable products. A ferredoxin, which functions as the electron donor to the hydrogenase of this organism was purified under anaerobic reducing conditions. It had a molecular weight of approximately 12,000 and contained 8 iron atoms and 8 cysteine residues/mol but lacked histidine or arginine residues. Reduction and oxidation of the ferredoxin each required 2 electrons/mol, which is consistent with the presence of two [4Fe-4S] clusters. The reduced protein gave rise to a broad rhombic electronic paramagnetic resonance spectrum, with gz = 2.10, gy = 1.86, gx = 1.80, and a midpoint potential of -345 mV (at pH 8). However, this spectrum represented a minor species, since it quantitated to only approximately 0.3 spins/mol. P. furiosus ferredoxin is therefore distinct from other ferredoxins in that the bulk of its iron is not present as iron-sulfur clusters with an S = 1/2 ground state. The apoferredoxin was reconstituted with iron and sulfide to give a protein that was indistinguishable from the native ferredoxin by its iron content and electron paramagnetic resonance properties, which showed that the novel iron-sulfur clusters were not artifacts of purification. The reduced ferredoxin also functioned as an electron donor for H2 evolution catalyzed by the hydrogenase of the mesophilic eubacterium Clostridium pasteurianum. P. furiosus ferredoxin was resistant to denaturation by sodium dodecyl sulfate (20%, wt/vol) and was remarkably thermostable. Its UV-visible absorption spectrum and electron carrier activity to P. furiosus hydrogenase were unaffected by a 12-h incubation of 95 degrees C.     

Sex differences in the behaviour of immature captive lowland gorillas

Studies of the behaviour of 26 (12 males and 14 females) captive infant and juvenile lowland gorillas showed clear sex differences. Females showed greater interest in young infants and were more active in nest building as well as in solitary and social grooming. Males were more active in locomotive, dominance, and aggressive behaviour and in social play. Hand-rearing further increased aggression. Males were more aggressive when they lived with only one partner, and they rose in rank even above older females, a pattern that has not been observed in naturally reared gorillas.     

Effect of nucleotide cofactor structure on recA protein-promoted DNA pairing. 2. DNA renaturation reaction.

We have examined the effects of the structurally related nucleoside triphosphates, adenosine triphosphate (ATP), purine riboside triphosphate (PTP), inosine triphosphate (ITP), and guanosine triphosphate (GTP), on the recA protein-promoted DNA renaturation reaction (phi X DNA). In the absence of nucleotide cofactor, the recA protein first converts the complementary single strands into unit-length duplex DNA and other relatively small paired DNA species; these initial products are then slowly converted into more complex multipaired network DNA products. ATP and PTP stimulate the conversion of initial product DNA into network DNA, whereas ITP and GTP completely suppress network DNA formation. The formation of network DNA is also inhibited by all four of the corresponding nucleoside diphosphates, ADP, PDP, IDP, and GDP. Those nucleotides which stimulate the formation of network DNA are found to enhance the formation of large recA-ssDNA aggregates, whereas those which inhibit network DNA formation cause the dissociation of these nucleoprotein aggregates. These results not only implicate the nucleoprotein aggregates as intermediates in the formation of network DNA, but also establish the functional equivalency of ITP and GTP with the nucleoside diphosphates. Additional experiments indicate that the net effect of ITP and GTP on the DNA renaturation reaction is dominated by the corresponding nucleoside diphosphates, IDP and GDP, that are generated by the NTP hydrolysis activity of the recA protein.     

Wendell Stanley's dream of a free-standing biochemistry department at the University of California, Berkeley

Conclusion Scientists and historians have often presumed that the divide between biochemistry and molecular biology is fundamentally epistemological.¹⁰⁰ The historiography of molecular biology as promulgated by Max Delbrück's phage disciples similarly emphasizes inherent differences between the archaic tradition of biochemistry and the approach of phage geneticists, the ur molecular biologists. A historical analysis of the development of both disciplines at Berkeley mitigates against accepting predestined differences, and underscores the similarities between the postwar development of biochemistry and the emergence of molecular biology as a university discipline. Stanley's image of postwar biochemistry, with its focus on viruses as key experimental systems, and its preference for following macromolecular structure over metabolism pathways, traced the outline of molecular biology in 1950.Changes in the postwar political economy of research universities enabled the proliferation of disciplines such as microbiology, biochemistry, biophysics, immunology, and molecular biology in universities rather than in medical schools and agricultural colleges. These disciplines were predominantly concerned with investigating life at the subcellular level-research that during the 1930s had often entailed collaboration with physicists and chemists. The interdisciplinary efforts of the 1930s (many fostered by the Rockefeller Foundation) yielded a host of new tools and reagents that were standardized and mass-produced for laboratories after World War II. This commercial infrastructure enabled basic researchers in biochemistry and molecular biology in the 1950s and 1960s to become more independent from physics and chemistry (although they were practicing a physicochemical biology), as well as from the agricultural and medical schools that had previously housed or sponsored such research. In turn, the disciplines increasingly required their practitioners to have specialized graduate training, rather than admitting interlopers from the physical sciences.These general transitions toward greater autonomy for biochemistry and allied disciplines should not mask the important particularities of these developments on each campus. At the University of Caliornia at Berkeley, agriculture had provided, with medicine, significant sponsorship for biochemistry. The proximity of Lawrence and his cyclotrons supported the early development of Berkeley as a center for the biological uses of radioisotopes, particularly in studies of metabolism and photosynthesis. Stanley arrived to establish his department and virus institute before large-scale federal funding of biomedical research was in place, and he courted the state of California for substantial backing by promising both national prominence in the life sciences and virus research pertinent to agriculture and public health. Stanley's venture benefited significantly from the expansion of California's economy after World War II, and his mobilization against viral diseases resonated with the concerns of the Cold War, which fueled the state's rapid growth. The scientific prominence of contemporary developments at Caltech and Stanford invites the historical examination of the significance of postwar biochemistry and molecular biology within the political and cultural economy of the Golden State.In 1950, Stanley presented a persuasive picture of the power of biochemistry to refurbish life science at Berkeley while answering fundamental questions about life and infection. In the words of one Rockefeller Foundation officer,There seems little doubt in [my] mind that as a personality Stanley will be well able to dominate the other personalities on the Berkeley campus and will be able to drive his dream through to completion, which, incidentally, leaves Dr. Hubert [sic] Evans and the whole ineffective Life Sciences building in the somewhat peculiar position of being by-passed by much of the truly modern biochemistry and biophysics research that will be carried out at Berkeley. Furthermore, it seems likely that Dr. S's show will throw Dr. John Lawrence's Biophysics Department strongly in the shade both figuratively and literally, but should make the University of California pre-eminent not only in physics but in biochemistry as well.¹⁰¹ Stanley, Sproul, Weaver, and this officer (William Loomis) all testified to a perceptible postwar opportunity to capitalize on public support for biological research that relied on the technologies from physics and chemistry without being captive to them, and that addressed issues of medicine and agriculture without being institutionally subservient. What is striking, given the expectation by many that Stanley would be able to drive his dream through to completion, was that in fact he did not. Biochemists who had succeeded in making their expertise valued in specialized niches were resistant to giving up their affiliations to joint Stanley's liberated organization. Stanley's failure was not simply due to institutional factors: researchers as well as Rockefeller Foundation officers faulted him for his lack of scientific imagination, which made it difficult for him to gain credibility in leading the field. Moreover, many biochemists did not share Stanley's commitment to viruses as the key material for the new biochemistry.In the end, Stanley's free-standing department did become a first-rate department of biochemistry, but only after freeing itself from Stanley's leadership and his single-minded devotion to viruses. Nonetheless, the falling-out with the Berkeley biochemists was rapidly followed by the establishment of a Department of Molecular Biology, attesting to the unabating economic and institutional possibilities for an authoritative general biology (or two, for that matter) to take hold. In each case, following Stanley's dream sheds light on how the possible and the real shaped the (re)formation of biochemistry and molecular biology as postwar life sciences.