Role of light, carbon dioxide and nitrogen in regulation of buoyancy, growth and bloom formation of Anabaena flos-aquae

The availability of light, CO₂ and NH₄-N interacted to controlbuoyancy and growth of the gas vacuolate blue-green alga, Anabaenaflos-aquae. At high light intensities algal growth rates werehigh; however, the alga was non-buoyant regardless of the availabilityof CO₂ or NH₄-N. The mechanism for buoyancy loss involved increasedcell turgor pressures at higher light intensities which resultedin collapse of gas vacuoles. At lower light intensities algalgrowth rates and cell turgor pressures were reduced and buoyancywas controlled by the availability of CO₂ and inorganic nitrogen.Carbon dioxide limitation increased buoyancy, while reducedinorganic nitrogen availability reduced buoyancy. Mechanismsfor buoyancy regulation at low light intensities involved changesin cellular C/N ratios which appeared to affect the rate ofsynthesis and accumulation of protein-rich gas vacuoles. Algalspecific growth rates were combined with buoyancy data to forma single index (µ_bloom) to the rate of surface bloom formationof A.flos-aquae as a function of the availability of light,CO₂ and NH₄-N. The bloom formation index was enhanced with decreasedavailability of light and CO₂, and increased availability ofNH₄-N.     

Two-site exchange revisited: a new method for extracting exchange parameters in biological systems.

A new analysis is presented which links real volume fractions, relaxation rates, and intracompartmental exchange rates directly with apparent volume fractions and relaxation rates obtained from biexponential fits of transverse magnetization decay curves. The analysis differs from previous methods in that measurements from two paramagnetic doping levels are used to close the two-site exchange equations. Both the new method and one previously described by Herbst and Goldstein (HG) have been applied to paramagnetically doped whole-blood data sets. Significant differences in the calculated exchange parameters are found between the two methods. A small dependence of the intracellular relaxation rate on extracellular paramagnetic agent concentration, assumed nonexistent with the HG method, is inferred from the new analysis. The analysis was also applied to published data on perfused rat hearts, and we obtained a limited assessment of two-site exchange in this system.     

Isolation and characterization of the cDNA for pulmonary surfactant-associated protein-B (SP-B) in the rabbit

Pulmonary surfactant contains phospholipids including dipalmitoyl-phosphatidylcholine and three surfactant-associated proteins designated SP-A, SP-B and SP-C. A cDNA for rabbit SP-B has been isolated from a fetal (30 days gestation) rabbit lung cDNA library constructed in lambda gt11. The cDNA and deduced amino acid sequences show strong homology with the cDNAs and predicted 40 kDa proproteins for human and canine SP-B. Strong homology is also observed with the amino acid sequences directly determined for the mature 8 kDa bovine and porcine SP-B isolated from lung lavage. SP-B is remarkable for its high cysteine and proline content and for the hydrophobic nature of the organic solvent-soluble, mature protein. In vitro translation of sense but not antisense RNA transcribed from the cDNA led to the production of 40 kDa and 32 kDa proteins. These proteins were immunoprecipitated by an antibody raised against bovine SP-B. Northern blot analysis revealed the mRNA for rabbit SP-B appears in fetal rabbit lung late in gestation and falls slightly in the neonate.     

Genes for tRNAAsp,tRNAPro, tRNATyr and two tRNAsSer in wheat mitochondrial DNA

We have begun a systematic search for potential tRNA genes in wheat mtDNA, and present here the sequences of regions of the wheat mitochondrial genome that encode genes for tRNA^Asp (anticodon GUC), tRNA^Pro (UGG), tRNA^Tyr (GUA), and two tRNAs^Ser (UGA and GCU). These genes are all solitary, not immediately adjacent to other tRNA or known protein coding genes. Each of the encoded tRNAs can assume a secondary structure that conforms to the standard cloverleaf model, and that displays none of the structural aberrations peculiar to some of the corresponding mitochondrial tRNAs from other eukaryotes. The wheat mitochondrial tRNA sequences are, on average, substantially more similar to their eubacterial and chloroplast counterparts than to their homologues in fungal and animal mitochondria. However, an analysis of regions 150 nucleotides upstream and 100 nucleotides downstream of the tRNA coding regions has revealed no obvious conserved sequences that resemble the promoter and terminator motifs that regulate the expression of eubacterial and some chloroplast tRNA genes. When restriction digests of wheat mtDNA are probed with ³²P-labelled wheat mitochondrial tRNAs, <20 hybridizing bands are detected, whether enzymes with 4 bp or 6 bp recognition sites are used. This suggests that the wheat mitochondrial genome, despite its large size, may carry a relatively small number of tRNA genes.     

Industrial yeast strain improvement: construction of strains having the killer character and capable of utilizing starch

Summary A hybrid of Saccharomyces cerevisiae with the ability to utilize starch and to produce the killer toxin was constructed by the protoplast fusion technique. The hybrid was obtained in two steps. In the first, a wild killer strain was fused with a laboratory strain (S. cerevisiae STA2). A fusion product which carried the killer factor and the ability to grow on starch was selected. In the second step, this hybrid was fused with a baker's yeast.     

Characterization of lymphoid tumors induced by a recombinant murine retrovirus carrying the avian v-myc oncogene. Identification of novel (B-lymphoid) tumors in the thymus

Lymphoid tumors induced by a recombinant murine retrovirus carrying the v-myc oncogene of avian MC29 virus were characterized. The Moloney murine leukemia virus myc oncogene (M-MuLV (myc], carried by an amphotropic MuLV helper, induced tumors in NIH Swiss and NFS/N mice after a relatively long latency (8 to 24 wk). Tumor masses appeared in the thymus, spleen, and lymph nodes. Flow cytometry of the tumor cells indicated that approximately 50% were positive for Thy 1.2. Most of these tumors also expressed one or more other cell surface markers of thymocytes and mature T cells (CD4, CD8). Southern blot hybridization revealed genomic rearrangements for the TCR beta genes. The TCR beta analysis suggested that the M-MuLV(myc)-induced Thy 1.2+ tumors were derived from somewhat less mature cells than tumors induced by M-MuLV, which is a classical non-acute retrovirus lacking an oncogene. The remainder of the M-MuLV(myc)-induced tumors were Thy 1.2-, but they were positive for Ly-5 (B220) and also for MAC-2. The Thy 1.2- tumors were characteristically located in the thymus. However, they were negative for TCR beta gene rearrangements. Some, but not all, of the Thy 1.2- tumors contained rearrangements for Ig genes. Additionally, they typically expressed mRNA specific for B but not for T cells. Thus, these thymic tumors had characteristics of the B cell lineage. Tumor transplantation experiments demonstrated that the Thy 1.2- tumor cells could reestablish in the thymus and spleen of irradiated hosts, and low level expression of the Thy 1 molecule was observed in the thymus but not the spleen on the first passage. After serial passage, one Thy 1- tumor altered its cell surface phenotype to Thy 1low B220-.     

Pulmonary paracoccidioidomycosis in immunized mice

Paracoccidioidomycosis was induced in immunized (IM) and non-immunized (NI) mice. The histopathology, the number of fungi in the lungs, the cellular (footpad test — FPT and macrophage inhibition factor assay — MIF) and humoral (immunodiffusion test) immune response were investigated serially postinfection. In the IM mice, at days 1 and 3, there was intense and predominant macrophagic-lymphocytic alveolitis with loose granulomatous reaction; at day 30, inflammation was mild. In the NI group, up to day 3, the lesions were focal; later there was formation of extensive epithelioid granuloma. The number of fungi in IM mice were always smaller than those of NI group. Immunization alone induced positive FPT and MIF indices with low titer of antibody. After infection, there was a significant decrease of the FPT indices in the IM group, which we interpreted as desensitization due to trapping of sensitized lymphocytes in the lungs. In conclusion, (1) The lesional pattern of pulmonary paracoccidioidomycosis in IM mice was similar to that of a hypersensitivity pneumonitis. This reaction was probably effective in reducing the extension of the infection and decrease the number of fungi. (2) In this model, pulmonary resistance against P. brasiliensis seems to be related to local and systemic delayed-type hypersensitivity reaction.     

Comparative effects of a recombinant and a mutein type of granulocyte colony stimulating factor on the growth of Meth-A fibrosarcoma with 5-fluorouracil chemotherapy

The present study was designed to evaluate the effects of a recombinant human G-CSF (rhG-CSF) and a mutein G-CSF(KW-2228) on leucopenia and tumor growth in mice treated with 5-fluorouracil (5-FU). In normal mice, the number of leucocytes (white blood cell, WBC) reached the peak 12 hours after a single injection of either type of G-CSF and decreased to the normal level after 24 hours. Daily administration induced a continuous increase in the WBC count, however, administrations at intervals did not. Meth-A fibrosarcoma was subcutaneously inoculated into the backs of syngeneic BALB/c mice. The mice were treated with 5-FU alone or with G-CSFs. Chemotherapy with 5-FU alone resulted in leucopenia and an insignificant inhibition of tumor growth. The conjunctive administration of G-CSFs with 5-FU resulted in a significantly augmented inhibition of tumor growth, and leukopenia was not seen. This augmenting effect was more prominent with KW-2228.These results suggest that in 5-FU chemotherapy G-CSFs may be beneficial in restoring the number of leucocytes from leucopenic state and in augmenting the tumor inhibitory effect. Furthermore, KW-2228 may be more beneficial than the natural type rhG-CSF.     

Rioarribasaurus,a new name for a Late Triassic dinosaur from New Mexico (USA)

The Late-Triassic-dinosaur generic nameCoelophysis Cope 1889 (type species C.bauri [Cope 1887]) is a nomen dubium because the lectotype of C.bauri, AMNH 2722, is four sacral vertebrae and a pubic process of the ilium that are not diagnostic. Dinosaur specimens from the famous Whitaker (“Coelophysis”) quarry in the Rock Point Member of the Chinle Formation at Ghost Ranch, New Mexico thus lack a valid name. We create a new genus and species name,Rioarribasaurus colberti, for these specimens.