Influence of a loblolly pine (Pinus taeda L.). Culture medium and its components on growth and somatic embryogenesis of the wild carrot (Daucus carota L.)

A new culture medium, originally designed and shown to grow cell suspensions from a variety of loblolly pine (Pinus taeda L.) explants, was used to study growth and somatic embryogenesis of the wild carrot (Daucus carota L.) in cell suspensions. The new loblolly pine medium (LM) differed from the standard wild carrot medium (WCM) in having very low Ca²⁺, very high Mg²⁺, and enrichment with PO _inf4 ^sup3– and microelements. When WCM was altered to contain levels of Ca²⁺ or Ca²⁺ and Mg²⁺ equivalent to LM, it supported neither growth nor embryogenesis of the wild carrot. However, growth and embryogenesis in LM was superior to WCM. The phosphate level in WCM was found to be suboptimal.     

Isolation and characterization of the membrane envelope enclosing the bacteroids in soybean root nodules

The membrane envelope enclosing the bacteroids in soybean root nodules is shown by ultrastructural and biochemical studies to be derived from, and to retain the characteristics of, the host cell plasma membrane. During the early stages of the infection process, which occurs through an invagination, Rhizobium becomes surrounded by the host cell wall and plasma membrane, forming the infection thread. The cell wall of the infection thread is degraded by cellulolytic enzyme(s), leaving behind the enclosed plasma membrane, the membrane envelope. Cellulase activity in young nodules increases two- to threefold as compared to uninfected roots, and this activity is localized in the cell wall matrix of the infection threads. Membrane envelopes were isolated by first preparing bacteroids enclosed in the envelopes on a discontinuous sucrose gradient followed by passage through a hypodermic needle, which released the bacteroids from the membranes. This membrane then sedimented at the interface of 34--45% sucrose (mean density of 1.14 g/cm3). Membranes were characterized by phosphotungstic acid (PTA)-chromic acid staining. ATPase activity, and localization, sensitivity to nonionic detergent Nonidet P-40 (NP-40) and sodium dodecyl sulfate (SDS) gel electrophoresis. These analyses revealed a close similarity between plasma membrane and the membrane envelope. Incorporation of radioactive amino acids into the membrane envelope proteins was sensitive to cycloheximide, suggesting that the biosynthesis of these proteins is primarily under host-cell control. No immunoreactive material to leghemoglobin antibodies was found inside or associated with the isolated bacteroids enclosed in the membrane envelope, and its location is confined to the host cell cytoplasmic matrix.     

Genome organization of RNA tumor viruses II. Physical maps of in vitro-synthesized Moloney murine leukemia virus double-stranded DNA by restriction endonucleases.

Physical maps of the genome of Moloney murine leukemia virus (M-MLV) DNA were constructed by using bacterial restriction endonucleases. The in vitro-synthesized M-MLV double-stranded DNA was used as the source of the viral DNA. Restriction endonucleases Sal I and Hind III cleave viral DNA at only one site and, thus, generate two DNA fragments. The two DNA fragments generated by Sal I are Sal IA (molecular weight, 3.5 x 10(6)) and Sal IB (molecular weight, 2.4 x 10(6)) and by Hind III are Hind IIIA (molecular weight, 3.6 x 10(6) and Hind IIIB (molecular weight, 2.3 x 10(6)). Restriction endonuclease Bam I generates four fragments of molecular weights of 2.1 x 10(6) (Bam IA), 2 X 10(6) (Bam IB), 1.25 X 10(6) (Bam IC), and 0.24 x 10(6) (Bam ID), whereas restriction endonuclease Hpa I cleaves the M-MLV double-stranded DNA twice to give three fragments of molecular weights of 4.4 x 10(6) (Hpa IA), 0.84 X 10(6) (Hpa IB), and 0.74 x 10(6) (Hpa IC). Digestion of M-MLV double-stranded DNA with restriction endonuclease Sma I produces four fragments of molecular weights of 3.9 x 10(6) (Sma IA), 1.3 X 10(6) (Sma IB), 0.28 X 10(6) (Sma IC), and 0.21 x 10(6) (Sma ID). A mixture of restriction endonucleases Bgl I and Bgl II (Bgl I + II) cleaves the viral DNA at four sites generating five fragments of approximate molecular weights of 2 x 10(6) (Bgl + IIA), 1.75 X 10(6) (Bgl I + IIB), 1.25 X 10(6) (Bgl I + IIC), 0.40 X 10(6) (Bgl I + IID), and 0.31 x 10(6) (Bgl I + IIE). The order of the fragments in relation to the 5' end and 3' end of the genome was determined either by using fractional-length M-MLV double-stranded DNA for digestion by restriction endonucleases or by redigestion of Sal IA, Sal IB, Hind IIIA, and Hind IIIB fragments with other restriction endonucleases. In addition, a number of other restriction endonucleases that cleave in vitro-synthesized M-MLV double-stranded DNA have also been listed.     

Heteroduplex Analysis of the Sequence Relationships Between the Genomes of Kirsten and Harvey Sarcoma Viruses, Their Respective Parental Murine Leukemia Viruses, and the Rat Endogenous 30S RNA

The sequence relations between Kirsten murine sarcoma virus (Ki-SV), Harvey murine sarcoma virus (Ha-SV), and a rat endogenous 30S RNA were studied by electron microscope heteroduplex analysis. The sequence relationships between the sarcoma viruses and their respective parental murine leukemia viruses (Kirsten and Moloney murine leukemia viruses), as well as between the two murine leukemia viruses, were also studied. The only observed nonhomology feature of the Kirsten murine leukemia virus/Moloney murine leukemia virus heteroduplexes was a substitution loop with two arms of equal length extending from 1.80 +/- 0.18 kilobases (kb) to 2.65 +/- 0.27 kb from the 3' end of the RNA. It is believed that this feature lies in the env gene region of the viral genomes. The Ha-SV and Moloney murine leukemia virus genomes (respective lengths, 6.0 and 9.0 kb) were homologous in a 1.0 +/- 0.05-kb region at the 3' end and possibly over a 200-nucleotide region at the 5' ends; otherwise, they were nonhomologous. Ha-SV and Ki-SV (length, 7.5 kb) were homologous in the first 4.36 +/- 0.37-kb region from the 3' end and in a 0.70 +/- 0.15-kb region at the 5' end. In between, there was a nonhomology region, possibly containing a short (0.23-kb) region of partial or total homology. The heteroduplex analysis between rat endogenous 30S RNA and Ki-SV shows that there are mixed regions of sequence homology and nonhomology at both the 5' and 3' ends. However, there is a large (4-kb) region of homology between Ki-SV and the rat 30S RNA in the center of the genomes, with only a small nonhomology hairpin feature. These studies help to define the regions of homology between the Ha-SV and Ki-SV genomes with each other and with the rat endogenous 30S RNA. These regions may be related to the sarcoma genicity of the viruses. In particular, the 0.7-kb region of homology of Ha-SV with Ki-SV at the 5' ends may be related to the formation of a 21,000-dalton phosphoprotein in cells transformed by either virus.     

Characterization of Ca2+-ATPase activity in Streptomyces griseus.

Ca2+-ATPase activity has been characterized in Streptomyces griseus. The enzyme has a pH optimum of 8.5 at 37 degrees C. Its Ca2+ requirement can be substituted by Cd2+, Zn2+ and Mn2+. Mg2+ inhibits the enzyme non-competitively.     

Preparation of a complementary DNA for leghaemoglobin and direct demonstration that leghaemoglobin is encoded by the soybean genome

In soybean root nodules, leghaemoglobin (Lb) accounts for 25--30% of the total soluble protein but is not detected in other tissues. In order to determine whether the Lb genes are plant or bacterial in origin a cDNA probe for Lb was prepared from 9S poly (A) containing mRNA of root nodules. Although this 9S mRNA directed synthesis of predominantly three forms of Lb in vitro, the kinetics of hybridisation of cDNA and the 9S mRNA showed a transition at about 30% hybridisation which suggested that the 9S-cDNA was not pure Lb-cDNA. The abundant, Lb-cDNA was prepared by two cycles of hybridising 9S mRNA and cDNA to a Rot of 3 X 10(-3) and isolation of the hybridised cDNA on hydroxyapatite. The Lb-cDNA was homogeneous in hybridisation analysis with 9S mRNA and electrophoresis in 98% formamide gels. This cDNA hybridised with soybean DNA and not with Rhizobium DNA, thus directly demonstrating that Lb genes are of plant origin. Titration of Lb-cDNA with soybean DNA showed that Lb genes are reiterated about forty-fold per haploid genome.     

Structural vaccinology approach to investigate the virulent and secretory proteins of Bacillus anthracis for devising anthrax next-generation vaccine

Abstract

Communicated by Ramaswamy H. Sarma     

First mammal evidence from the Late Cretaceous of India for biotic dispersal between India and Africa at the KT transition

The Late Cretaceous record of mammals from India assumes great significance in view of the fact that it is the only Gondwanan landmass that has yielded definitive eutherian mammals. These mammals have variously been assigned to palaeoryctids, archontans or Eutheria incertae sedis. Well preserved lower molars recovered from a new mammal-yielding Deccan intertrappean site near Kisalpuri village, Dindori District, Madhya Pradesh (state), India, are described here under a new species Deccanolestes narmadensis sp. nov. The new fossil material indicates close phylogenetic relationship between Deccanolestes from India and Afrodon (Adapisoriculidae) from the Late Palaeocene of Africa and Europe. In view of older age and more primitive state of Deccanolestes teeth, it is inferred that Deccanolestes represents an ancestral morphotype from which the African/European adapisoriculid Afrodon may have been derived. This is the first compelling terrestrial fossil evidence for an early dispersal between India and Africa. Such a dispersal possibly involved an East African contact with India at the KT transition.