A TnphoA insertion within the Bradyrhizobium japonicum sipS gene, homologous to prokaryotic signal peptidases, results in extensive changes in the expression of PBM-specific nodulins of infected soybean (Glycine max) cells

Bradyrhizobium japonicum mutant 132 was obtained by random TnphoA mutagenesis of strain 110spc4. A 6.5 kb BamHI kanamycin-resistance-coding DNA fragment of mutant 132 was used as a hybridization probe to clone the corresponding wild-type fragment. DNA sequence analysis of a 3213 bp BamHI—ClaI fragment revealed that three open reading frames (ORFs) were encoded in the same orientation. Based on sequence similarities to other proteins in the database, the second ORF was called sipS (signal peptidase). The TnphoA insertion in mutant 132 was found to be in frame near the 3′ end of sipS. The resulting SipS—PhoA hybrid polypeptide was shown to be expressed in free-living B. japonicum and in Escherichia coli cultures. An immunoblot analysis with a polyclonal antibody directed against the alkaline phosphatase revealed the appearance of a weak signal of a 70 kDa polypeptide both in B. Japonicum and in E. coli, in agreement with the calculated size of the hybrid polypeptide. A much stronger 52 kDa band was also detected. Mutant 132 was specifically disturbed in the interaction with soybean (Glycine max) when the bacteria were released from the infection threads. The bacteroids were not stably maintained within the symbiosome. Numerous vesicles were found in the plant cytosol, which finally resulted in the formation of large vacuoles within the infected nodule cells. Immunohistochemical analyses with antibodies directed against nodulins of the peribacteroid membrane indicated a lower expression of these proteins. The mutant phenotype was genetically complemented by 4.4 kb BamHI fragment including sipS. Subfragments thereof also complemented a temperature-sensitive E. coli lepB mutant, demonstrating that the B. japonicum fragment was functionally replacing Lep^ts in E. coli. Genetic studies suggested that the three genes are organized in one common operon which is expressed from a promoter upstream of the sequenced region. Inactivation of the gene downstream of sipS did not result in a detectable phenotype.     

Late neogene biostratigraphy and paleoceanography of DSDP site 310 Central North Pacific and correlation with the Southwest Pacific

Late Neogene planktonic foraminifera have been examined at Site 310 in the Central North Pacific and their stratigraphic ranges and frequencies are presented here. Blow's (1969) zonation developed for tropical regions has been applied where applicable. Where tropical index taxa are rare or absent in this temperate region, Globorotalia crassaformis, and the evolutionary bioseries G. conoidea — G. conomiozea and G. puncticula — G. inflata have been found useful for zonal subdivisions. A correlation between stratigraphic ranges and frequency distributions of these species at Site 310 in the Central North Pacific, and Site 284 in the Southwest Pacific indicates that these species are relatively consistent biostratigraphic markers in temperate regions of both the North and South Pacific Oceans. An informal zonation for temperate latitudes of the Southwest Pacific has been established by Kennett (1973) and a similar zonal subdivision can be made at Site 310.Paleoclimatic/paleoceanographic interpretations based on coiling ratios, percent abundance, and phenotypic variations of Neogloboquadrina pachyderma indicate four major cold events during early, middle, and late Pliocene, and early Pleistocene. Faunal correlations of these events with similar events elsewhere in the Northeast and Southwest Pacific which have been paleomagnetically dated indicate the following approximate ages for these cold events: 4.7 Ma, 3.0 Ma, 2.6–1.8 Ma. and 1.2 Ma. Faunal assemblages have been divided into three groups representing cool, intermediate, and warmer water assemblages. Cool water assemblages are dominated by >60% N. pachyderma; intermediate temperature faunas are dominated by species of Globigerina and Globigerinita and contain between 20% and 30% N. pachyderma. Warmer water assemblages are dominated by species of Globorotalia and contain <10% N. pachyderma. Frequency oscillations within these groups, in addition to paleotemperature parameters evident in N. pachyderma, afford refined paleoclimatic/paleoceanographic interpretations.     

Synthesis of a complementary DNA to rat liver albumin mRNA.

NADPH reduces both liver microsomal cytochrome P-450 and cytochrome $\text{b}{}_5$. In the presence of CO, ferrous cytochrome P-450 can slowly transfer electrons to amaranth, an azo dye. This reaction is followed by the reoxidation of cytochrome $\text{b}{}_5$ which proceeds at essentially the same rate as does cytochrome P-450 oxidation. It is suggested that cytochrome $\text{b}{}_5$ directly reduces cytochrome P-450 in rat liver microsomes.     

The chromosomal arrangement of two linked actin genes in the sea urchin S. purpuratus.

Four distinct actin genes of the sea urchin Strongylocentrotus purpuratus have been isolated from a recombinant Charon 4 phage library of genomic DNA. The four genes differ considerably from each other in many of their restriction sites. Two of the four genes are closely linked; they are present in the same fragment of cloned DNA. This fragment has been extensively mapped, and some parts of the DNA have been sequenced. The two linked genes are oriented in the same direction, separated by 7.5 kb of DNA. One has an intron following the CAG that codes for the glutamine residue at position 121 in the amino acid sequence of actin. This represents the fifth distinct site at which introns have been found in actin genes, suggesting that the primordial actin gene had at least 6 exons and 5 introns. The actin genes from a distinctive family in which most introns have apparently been precisely excised from the genes.     

Mechanics of blood flow

The historical development of the mechanics of blood flow can be traced from ancient times, to Leonardo da Vinci and Leonhard Euler and up to the present times with increasing biological knowledge and mathematical analysis. In the last two decades, quantitative and numerical methods have steadily given more complete and precise understanding. In the arterial system wave propagation computations based on nonlinear one-dimensional modeling have given the best representation of pulse wave propagation. In the veins, the theory of unsteady flow in collapsible tubes has recently been extensively developed. In the last decade, progress has been made in describing the blood flow at junctions, through stenoses, in bends and in capillary blood vessels. The rheological behavior of individual red blood cells has been explored. A working model consists of an elastic membrane filled with viscous fluid. This model forms a basis for understanding the viscous and viscoelastic behavior of blood.     

Purification and amino acid composition of the hyperglycemic neurohormone from the sinus gland ofOrconectes limosus and comparison with the hormone fromCarcinus maenas

Summary The hyperglycemic neuropeptide was purified to homogeneity from sinus glands of the crayfish,Orconectes limosus, by a simple two-step procedure consisting of preparative polyacrylamide gel electrophoresis followed by gel chromatography on Sephadex G-50. A total of 40 g was obtained from 1,670 lyophilized sinus glands. The molecule consists of 58 amino acid residues plus an undetermined number of Trp residues. The following amino acid composition was found: Asx₈; Thr₂; Ser₃; Glx₆; Pro₁; Gly₂; Ala₃; 1/2 Cys₄; Val₅; Met₁; Ile₃; Leu₅; Tyr₅; Phe₃; Trp_n.d.; His₀; Lys₃; Arg₄. A minimal MW of 6,812 was calculated. The N-terminal residue appears to be blocked. Analysis of the pure hormone on an isoelectric focusing gel gave an pI of 5.04–5.10. The hormone differs from that ofCarcinus (Keller and Wunderer, 1978) in its amino acid composition and pI (Carcinus: 4.55–4.63). The following features are common for both theOrconectes and theCarcinus hormone: the size of the molecule, the blocked N-terminus, the presence of two intrachain disulfide bridges and the general acidic nature. A dose ofOrconectes hormone which is highly effective in this species has no or only very little effect inUca, whereas the same dose ofCarcinus hormone, which is markedly hyperglycemic in the brachyuranUca, exhibits no effect in the astacuranOrconectes. In animals of 10 g live weight, injection of 1.9 pmol/animal causes a threefold increase in the hemolymph glucose level.Dedicated to Professor L.H. Kleinholz on the occasion of his 70^th birthday     

Transcutaneous pO2 of volunteers during hyperbaric oxygenation

Continuous transcutaneous pO2 measurements (tcPO2 measurements) were performed in healthy volunteers who were breathing air and oxygen under hyperbaric conditions (max. 4 ata). The results show a close correlation of PO2 values measured by the noninvasive method, in blood from discret arterial punctures, chamber PO2, respectively, the PO2 of the inspiratory gas mixture which was checked up to maximal values of 2,200 mm Hg. The PO2 in the arterial blood samples was measured immediately after the puncture insight the hyperbaric chamber using a specially designed through electrode.     

The effect of propylthiouracil (PTU) on heat production in chickens maintained on different levels of nutrition

Using the method of forced feeding on higher and lower levels, two groups of chickens differring in growth rate were obtained. In the chickens of the two groups 72 measurements of heat production were made. Chickens of these groups were compared considering either the same age or similar body weight. It has been found that propythiouracil treatment (120 mg/kg duging 10 consecutive days) decreases heat production in the chickens of both groups. However, this effect was much more pronounced in the birds maintained on the higher level of nutrition and growing more rapidly than in those maintained on the lower level of nutrition and growing slowly.     

Studies of the biosynthesis of actinomycin in protoplasts from Streptomyces antibioticus.

Protoplasts actively synthesizing actinomycins have been prepared from Streptomyces, antibioticus. They showed an absolute requirement for the presence of oxygen, galactose, and alkaline earth ions. Sucrose was most efficient as an osmotic stabilizer. However, in air-saturated buffer the protoplasts seemed to be slightly inhibited in their metabolism. This is expressed by the appearance of 4-methyl-3-hydroxyanthranilic acid and the inability to utilize [1?¹⁴C]sarcosine for actinomycin synthesis. Evidence has been obtained that sarcosine and N-methyl-l-valine are not free precursors of the peptide-bound N-methyl-amino acids. It is further demonstrated that synthesis of actinomycin IV and actinomycin V differ from each other with respect to their different susceptibilities against the changings in the physiological environment of the protoplasts. Actinomycin synthesis is severely reduced when protoplasts are incubated in the presence of 10^?3, m methionine.