Gametogenesis in Chlamydomonas II. Effect of cycloheximide on the induction of sexuality

An inhibitor of protein synthesis, CHI, was used to study therelation of protein synthesis to the induction of sexualityin Chlamydomonas. (1) Freshly prepared CAP and DSm did not inhibitinduction, but CAP solution which had been illuminated causedstrong inhibition. (2) CHI inhibited the induction of sexualityremarkably, but not completely. The induction of sexuality maybe of two types, CHI-sensitive and CHI-insensitive. (3) Vigorousagitation of gametogenic cultures resulted in a marked inhibitionof induction in the presence of CHI, and less in its absence.(4) The amounts of light required for CHI-sensitive and CHI-insensitiveinduction differed; respectively, 5 min of illumination at ca.8,000 lux and 3 hr of illumination at the same intensity. (5)For complete blockage of CHI-sensitive induction, the additionof CHI 50 min before illumination was needed. (6) The activitiesof CHI-sensitive and CHIinsensitive induction changed with theage of the culture. (7) It was supposed that some material(s)inhibiting gametogenesis was present in the medium of the agedculture. Based on these results, a hypothetical scheme for gametogenesisis presented. (Received March 7, 1973; )     

Reconstitution of photosynthetic charge accumulation and oxygen evolution in CaCl2-treated PS II particles: II: EPR evidence for reactivation of the S1 → S2 transition in CaCl2-treated PS II particles with the 17-, 23-, and 34-kDa proteins

Extraction of PS II particles with 1 M CaCl₂ caused complete disappearance of the light-induced signal of the possible Kok S₂ state of the water-splitting complex and total loss of the O₂, evolving activity, concomitant with perfect removal of the 17-, 23- and 34-kDa proteins from the particles. The recovery of the multiline signal in the CaCl₂-treated PS II was performed by reinserting the 34-kDa protein, when CI^? was present in the solution for the EPR measurement. However, in the absence of Cl^?, besides the 34-kDa protein, the 17- and 23-kDa proteins were required for the recovery of the signal. These results are compared with the results on the recovery of the O₂, evolution in the reconstituted PS II to examine the role of these three proteins on the water splitting.     

Radiolaria: Sinking population,standing stock,and production rate

A method is presented for estimating sinking population, rate of production, and residence time in the living zone for Radiolaria. This method employs vertical flux measurements from PARFLUX sediment traps and laboratory sinking speed measurements of the radiolarian skeletons.The estimated population sinking through the oceanic water column is approximately equal to the standing stock at several hundred meters depth reported from direct measurements by other workers. The rate of production of total Radiolaria was estimated to be approximately 80 shells m^?3 day^?1 in the western equatorial Atlantic (E) and central Pacific (P₁) stations and 230 shells m^?3 day^?1 in the Panama Basin (PB). The production of Nassellaria is greater than that of the other suborders. The average residence time for Radiolaria in the living zone (0–200 m) was estimated to be between 16 and 42 days.     

A 460-kb DNA Sequence of the Escherichia coli K-12 Genome Corresponding to the 40.1-50.0 min Region on the Linkage Map

The 465,813 base pair sequence corresponding to the 40.1–50.0min region on the genetic map of Escherichia coli K-12 (W3110)was determined. Analysis of the sequence revealed that thisregion contained at least 466 potential open reading frames,of which 187 (40%) were previously reported, 105 (23%) werehomologous to other known genes, 103 (22%) were identical orsimilar to hypothetical genes registered in databases, and theremaining 71 (15%) did not show a significant similarity toany other gene. At the 45.2–46.0 min region, we founda very large cluster of about 30 genes, whose functions areinvolved in the biosynthesis of polysaccharides as the componentsof outer membranes. In addition, we identified anew asn-tRNAgene, designated asnW, between the asnT and asnU genes and anew lysogenic phage attachment site as the cis-element.     

Comparison of properties of leaf and root glutathione reductases from spinach

Glutathione reductase (GR; EC 1.6.4.2) was purified from spinach roots (rGR) to homogeneity in terms of SDS-PAGE, and its properties were compared with those of the enzyme from spinach leaves (IGR). The two enzymes had similar native molecular (118000) and subunit masses (58000) and immunochemical properties, but different pH optima (ca pH 7.8 for IGR, ca pH 7.2 for rGR) and amino acid compositions. Peptide maps of two GRs showed that they differed from each other. The N-terminal amino acid of the IGR was glycine and that of the rGR was blocked. The partial amino acid sequence of the N-terminal region of the IGR was determined to the 11 th residue and it was found that the sequence of 8 amino acids of the IGR had 100% homology with that of the putative chloroplast GR from Arabidopsis and pea.     

Particle selectivity of pelagic tintinnid agglutination

Scanning electron microscopic observation reveals that several agglutinated, pelagic tintinnid taxa apparently possess a capability of incorporating specific mineral grains, such as monospecific coccoliths, for their loricae. Since the ocean water generally contains other coccolith taxa, as well as diatoms and clays, it seems possible that the tintinnids can single out a particular coccolithophore species from the variety of suspended matter for their loricae-building.