Effects of radiation,temperature and humidity on photosynthesis,transpiration and water use efficiency of oilseed rape (Brassica campestris L.)

The net photosynthetic rate (F), transpiration rate (Q) and water use efficiency (F/Q) of oilseed rape (Brassica campestris L. cv. Span) was studied under a range of atmospheric conditions by gas exchange techniques. The plants were at the full bloom/pod initiation stage of development at the time of measurement. The environmental conditions consisted of various levels of photosynthetically active radiation (100 to 2800 (μmol m^?2 s^?1 PAK: 400–700 nm), air temperature (10 to 42°C) and vapour pressure deficit (0.7 to 2.1 kPa VPD). The peak values ofF were recorded at 1600 μmol m^?2 s^?1 PAR, 20°C air temperature and 1.2 kPa VPD of air in the chamber. Q increased with increasing PAR, air temperature and VPD. However, theF/Q remained high and almost constant from 600 to 1600 μmol m^?2 s^?1 PAR, but declined at the low and high photon flux densities.F/Q decreased progressively with increase in air temperature and VPD of air in the chamber.     

Separation of urine proteins on the anion-exchange resin mono QTM

Proteins excreted in urine due to renal failure were separated on Mono Q^TM, a new strong anion exchanger designed for fast high-resolution protein separations. The separation procedure was divided into two steps. The first step involved removal of low-molecular- weight substances by rapid desalting on a Sephadex G-25 Superfine column. In the second step, the total protein fraction (3–6 ml) was loaded onto the Mono Q column with the aid of a superloop. The proteins were adsorbed onto the top of the ion-exchanger column and gradually displaced by a combined pH and salt gradient in 40 min. The choice of ion exchanger and initial operating conditions were based on data obtained from electrophoretic titration curve experiments. Identification of separated proteins was achieved by fused rocket electrophoresis and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, respectively.     

Characterization of human loricrin. Structure and function of a new class of epidermal cell envelope proteins

We have isolated and characterized a full-length cDNA clone encoding human loricrin. Curiously, this protein displays major differences from the recently described mouse loricrin (Mehrel, T., Hohl, D., Nakazawa, H., Rothnagel, J.A., Longley, M.A., Bundman, D., Cheng, C.K., Lichti, U., Bisher, M.E., Steven, A. C., Steinert, P.M., Yuspa, S.H., and Roop, D.R. (1990) Cell 61, 1103-1112). Although both proteins are glycine-serine-cysteine-rich, the sequences have not been conserved. However, analysis of the sequences reveals a common motif of quasi-peptide repeats of an aliphatic or aromatic amino acid residue followed by several glycine and/or serine and cysteine residues. These sequences are interspersed and flanked by short glutamine- or glutamine/lysine-rich peptides. Thus loricrins consist of a family of cell envelope proteins of highly variable sequences that nevertheless retain common structural elements. We show that unlike all other putative protein components of the cell envelope, loricrins are highly insoluble, due at least in part to cross-linking by disulfide bonds. Furthermore, we have isolated four peptides from purified human cell envelopes that contain recognizable loricrin sequences and which are cross-linked by the N epsilon-(gamma-glutamyl)lysine isodipeptide bond. The presence of such bonds thus affords an explanation for the extraordinary insolubility of loricrin by cross-linking to the cell envelope and can also explain the low steady-state levels of monomeric loricrin in cytoskeletal extracts of epidermis. This study represents the first report of this isodipeptide cross-link in a protein component of the cornified cell envelope. We propose a model for the structure of loricrin in which (i) the unusual glycine-serine-rich sequences adopt a flexible loop conformation, indexed on the recurrent aliphatic residues; (ii) inter- or intramolecular isodipeptide and disulfide cross-links induce or stabilize folding of loricrin so as to form a more compact rosette-like structure; and (iii) the presence of the flexible glycine-rich loops necessarily will impact a flexible character to the cell envelope and entire epithelium.     

Phytoplankton and zooplankton of the Westport River Estuary,Massachusetts (USA)

Zooplankton and phytoplankton samples were simultaneously collected at approximately biweekly intervals over most of an annual cycle in the Westport River Estuary, Massachusetts. Phytoplankton numbers were overwhelmingly dominated throughout the study by athecate nanoplankton <5 µm in diameter. The zooplankton was primarily composed of copepod nauplii. Periods of occurrence of other zooplankters such as adult copepods, marine cladocerans, meroplankters and ctenophores were similar to those recorded for adjacent estuaries. Our results emphasize the abundance of smaller plankters that have been historically undersampled.     

On Wolff's law of trabecular architecture.

Several studies suggest that the yield strain in cancellous bone may be uniformly distributed and isotropic. Yield strain was reported to be independent of textural anisotropy in bovine cancellous bone [Turner, J. biomech. Engng 111, 1-5 (1989)] and it is plausible that yield strain is isotropic in human cancellous bone as well. In this paper, it is hypothesized that uniform, isotropic strain represents a goal of cancellous bone adaptation, i.e. cancellous bone alters its structure to maintain uniform, isotropic peak strains. Therefore, textural anisotropy must exactly cancel the anisotropy of the peak principal stresses imposed upon cancellous bone. When evaluating the relationships between mechanical properties of cancellous bone and trabecular architecture, it was found that over 90% of the variance of yield strength can be explained by one term--rho 2H3 (where rho is apparent density and H is the normalized anisotropy (fabric) constant). Furthermore, this single term explains 70-78% of the variance in Young's modulus of cancellous bone. Based upon these findings, it was postulated that fabric adaptation goes as Hi/Hj = [ sigma i/sigma j[, where Hi and Hj are fabric eigenvalues in the i- and the j-direction and sigma i and sigma j are peak principal stresses.     

In vivo human somatic mutation: frequency and spectrum with age.

The number and molecular nature of in vivo mutations in relation to age was studied at the autosomal HLA-A locus in human lymphocytes. Mutant lymphocytes were isolated by immunoselection, cloned at limiting dilution and enumerated, and the HLA-A gene and other polymorphic gene loci on chromosome 6 were studied by Southern blotting to determine gene dosage and loss of heterozygosity. Results of 167 assays in 73 individuals showed that the total number of mutant lymphocytes increased significantly with age from a geometric mean frequency of 0.71 x 10(-5) in neonates to 6.53 x 10(-5) in elderly individuals. Analysis of rearrangement of T lymphocyte receptor beta or gamma chain genes gave a best estimate of 3.3% for the proportion of mutant lymphocytes detected which are clonally related. Molecular study of 434 mutants from 31 individuals showed no change on Southern blotting in 64.7%, gene deletion in 2.8% and mitotic recombination in 32.5%. Two mutants due to gene conversion but no mutants due to non-disjunction were detected. The number of 'no change' and recombination mutants increased significantly with age. There was a significant difference between individuals in the proportion of mutants which resulted from mitotic recombination and the data suggested that the proportion was bimodally distributed. The point of crossing-over in recombination mutants was predominantly randomly distributed between the HLA-A locus and the centromere.     

Dark inhibition of ribulose-1,5-bisphosphate carboxylase/oxygenase in legumes: A biosystematic study

2-carboxyarabinitol 1-phosphate (CA 1-P) is a naturally occurring inhibitor of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Members of the Fabaceae exhibit a particularly wide range in the extent of CA 1-P accumulation during darkness and include Phaseolus vulgaris, whose dark/light regulation of Rubisco activity is principally achieved by synthesis/degradation of CA 1-P. An extensive survey of the degree of dark inhibition of Rubisco was undertaken for the subfamily Papilionoideae to elucidate evolutionary patterns in the occurrence of this regulatory mechanism. Seventy-five species from 21 tribes were examined. Dark inhibition of Rubisco was found in ancestral tribes such as the Sophoreae, but was substantially reduced or absent in representative species of three more recently evolved tribes, Cicereae, Hedysareae and Vicieae. We conclude that regulation of Rubisco by CA 1-P is neither of recent origin nor of restricted distribution among the Papilionoideae. On the contrary, it becomes lost or less pronounced only in a minority of the more evolutionarily advanced species in this important subfamily.     

Marine biosurfactants. IV. Production,characterization and biosynthesis of an anionic glucose lipid from the marine bacterial strain MM1

Summary During screening for biosurfactants among marine, n-alkane-utilizing bacteria, low- and high-molecular surface-active substances were detected. The marine bacterial strain MM1 was found to synthesize a novel glycolipid that has not so far been cited in the literature. Both ¹H, ¹³C-nuclear magnetic resonance spectroscopic and positive ion fast atom bombardment mass spectrometer studies led to the identification of a glucose lipid consisting of four 3-OH-decanoic acids, which are linked together by ester bonds. The lipophilic moiety is coupled glycosidically with C-1 of glucose. The glucolipid reduced the surface tension from 72 mN/m to 30 mN/m while the minimum interfacial tension towards n-hexadecane was lowered to values smaller than 5 mN/m. Correspondence to: S. Lang     

Tyrosinate fluorescence lifetimes for oxytocin and vasopressin in receptor-simulating environments: relationship to biological activity and 1H-NMR data

Nanosecond time-resolved tyrosinate fluorescence lifetimes were compared for oxytocin (OXT) and vasopressin (AVP) in propylene glycol. Long-lifetime tyrosinate fluorescence (LTF), characteristic of stable intramolecular hydrogen bond formation of the Tyr hydroxyl group, was present for OXT but not AVP in propylene glycol. The Tyr OH proton was also found to be labile for OXT but not AVP in DMSO by 1H-NMR. The spectroscopic data illustrate that the Tyr hydroxyl in OXT participates in an intramolecular hydrogen bond in certain receptor-simulating environments; the absence of potent LTF for [Ala5] OXT suggests that the Tyr hydroxyl of OXT forms an H-bond with the Asn5 carboxamide side-chain. The lability of the Tyr OH proton of OXT, but not AVP, is in accord with the biological activities of the peptides (OXT 100%, AVP 1%) in the rat uterus assay, suggesting that propylene glycol and DMSO mimic the environment at uterine receptors. 1H-NMR studies in DMSO demonstrate that for AVP there is a perpendicular-plate ring pairing interaction between the Tyr and Phe side-chains in which the hexagonal axis of the Tyr ring interacts with the face of the Phe ring. The present findings are discussed in terms of the proposed "cooperative model" for neurohypophysial hormone action.     

Changes in and partial identification of the plasminogen activator and plasminogen activator inhibitor systems during ovarian follicular maturation in the pig

Plasminogen, plasmin, and plasminogen activator (PA) activities and PA and PA inhibitor (PAI) contents were measured in granulosa (GC) and theca interna cell extracts and follicular fluid (FF) obtained from preovulatory follicles of prepubertal gilts treated with eCG and hCG to induce follicular growth and ovulation. Plasmin activity in FF increased just before the time of expected ovulation. This increase was not attributable to changes in plasminogen levels, which remained relatively constant during preovulatory follicular development. The increase in follicular plasmin levels was associated with significant (p less than 0.01) increases in PA activity and content and decreases in PAI content in GC and FF. Western blot analysis suggested that follicular PA activity was represented principally by two forms of tissue type PA (t-PA) each with a pI of 7.8 and with molecular masses of 72,000 and 78,000 daltons, respectively. Two PA-PAI complexes of 126,000 and 130,000 daltons were observed. These complexes were partially dissociated with nucleophilic agents into two t-PA-like forms and a 52,000-dalton PAI protein with a pI of 4.8. Biochemical characteristics of the PAI protein suggest that it belongs to the same class of inhibitors as bovine and human PAI-1. These data indicate that rupture of the porcine ovarian follicle is temporally associated with a net increase in PA activity and an increase in plasmin activity. The increase in PA activity appears to be regulated by changes in PA and PAI content.