Rhizome gravitropism precedes gravimorphogenesis after inversion of the green algal coenocyte Caulerpa prolifera (Caulerpales)

Previous investigations reported that the marine alga Caulerpa prolifera, a giant coenocyte, had a fast morphogenetic response to a change in position with regard to gravity: the next rhizoid formed approximately 1 day later on the new underside of the inverted rhizome (Jacobs and Olson, 1980, American Journal of Botany 67: 141–146). Preceding the change in site of rhizoid development was a striking accumulation of amyloplasts at the new prospective rhizoid-initiation site in the rhizome tip. Detailed monitoring with video equipment of inverted Caulerpa plants, growing under controlled conditions, now reveals that after the amyloplast accumulation, but before the gravimorphogenetic effect on rhizoid development, the inverted rhizome tip shows a negative gravitropism that restores it to its normally upturned position. Because the experiments were performed with two-sided illumination, this was clearly not a phototropic response.     

Phospholipase A2 inhibitors from marine algae

Twelve out of twenty-nine compounds isolated from benthic marine algae from the phyla Chlorophyta, Phaeophyta and Rhodophyta have been found to be potent inhibitors of bee venom derived phospholipase A₂ (PLA₂) (> 50%) in the M range. The compounds investigated were from: Bryopsis pennata, Rhipocephalus phoenix, Caulerpa prolifera, C. racemosa, C. bikinensis, Cymopolia barbata, Laurencia cf. palisada, Laurencia sp., Ochtodes crockeri, Liagora farinosa, Sphaerococcus coronipifolius, Phacelocarpus labillardieri, Dictyota sp., B furcaria galapagensis, Stypopodium zonale, Dictyopteris undulata, Stoechospermum marginatum, Dictyopteris divaricata, Dilophus fasciola and Dilophus sp. This is the first report of bee venom PLA₂ inhibition in vitro by pure compounds isolated from marine algae.     

Characterization of a high-affinity binding site for a DNA-binding protein from sea urchin embryo mitochondria.

Based on electrophoretic mobility shift assays, DNase I footprinting and modification interference analyses we have identified a sequence-specific DNA-binding protein in blastula stage mitochondria of the sea urchin Strongylocentrotus purpuratus, which interacts with a binding site around the major pause site for DNA replication. This region straddles the boundary of the genes for ATP synthase subunit 6 and cytochrome c oxidase subunit III, and contains also a prominent origin of lagging-strand synthesis. The protein is thermostable, and its natural high-affinity binding site comprises the sequence 5'-AGCCT(N7)AGCAT-3'. Binding studies have demonstrated that two copies of the imperfect repeat, as well as the 7 bp spacing between them, are essential for tight binding. Based on the location of its binding site, we tentatively designate the protein mitochondrial pause-region binding protein (mtPBP) 1.     

Molecular characterization of the proteinase-encoding gene, prb1, related to mycoparasitism by Trichoderma harzianum

The soil fungus Trichoderma harzianum is a mycoparasitic fungus known for its use as a biocontrol agent of phytopathogenic fungi. Among other factors, Trichoderma produces a series of antibiotics and fungal cell wall-degrading enzymes. These enzymes are believed to play an important role in mycoparasitism. Among the hydrolytic enzymes, we have identified a basic proteinase (Prb1) which is induced by either autoclaved mycelia, fungal cell wall preparation or chitin; however, the induction does not occur in the presence of glucose. The proteinase was purified and biochemically characterized as a serine proteinase of 31 kDa and pl 9.2. Based on the sequence of three internal peptides, synthetic oligonudeotide probes were designed. These probes allowed subsequent isolation of a cDNA and its corresponding genomic clone. The deduced amino acid sequence indicates that the proteinase is synthesized as a pre-proenzyme and allows its classification as a serine proteinase. Northen analysis shows that the induction of this enzyme is due to an increase in the corresponding mRNA level.     

Perturbed glial scaffold formation precedes axon tract malformation in Drosophila mutants

The longitudinal glia (LG), progeny of a single glioblast, form a scaffold that presages the formation of longitudinal tracts in the ventral nerve cord (VNC) of the Drosophila embryo. The LG are used as a substrate during the extension of the first axons of the longitudinal tract. I have examined the differentiation of the LG in six mutations in which the longitudinal tracts were absent, displaced, or interrupted to determine whether the axon tract malformations may be attributable to disruptions in the LG scaffold. Embryos mutant for the gene prospero had no longitudinal tracts, and glial differentiation remained arrested at a preaxonogenic state. Two mutants of the Polycomb group also lacked longitudinal tracts; here the glia failed to form an oriented scaffold, but cytological differentiation of the LG was unperturbed. The longitudinal tracts in embryos mutant for slit fused at the VNC midline and scaffold formation was normal, except that it was medially displaced. Longitudinaltracts had intersegmental interruptions in embryos mutant for hindsight and midline. In hindsight, there were intersegmental gaps in the glial scaffold. In midline, the glial scaffold retracted after initial extension. LG morphogenesis during axonogenesis was abnormal in midline. Commitment to glial identity and glial differentiation also occurred before scaffold formation. In all mutants examined, the early distribution of the glycoprotein neuroglian was perturbed. This was indicative of early alterations in VNC pattern present before LG scaffold formation began. Therefore, some changes in scaffold formation may have reflected changes in the placement and differentiation of other cells of the VNC. In all mutants, alterations in scaffold formation preceded longitudinal axon tract formation. © 1993 John Wiley & Sons, Inc.     

Relative intensity of muscular contraction during shivering.

The intensity of cold-induced shivering, quantified by surface electromyography (EMG) and then expressed as a function of the maximal myoelectrical activity (integrated EMG) obtained during a maximum voluntary contraction (MVC), was examined in this study in individuals classified by body fat. In addition, the relationship between shivering and metabolic rate (MR) and the relative contribution of various muscle groups to total heat production were studied. Ten seminude male volunteers, 5 LEAN (less than 11% body fat) and 5 NORM (greater than 15% body fat) were exposed to 10 degrees C air for 2 h. EMG of six muscle groups (pectoralis major, rectus abdominis, rectus femoris, gastrocnemius, biceps brachii, and brachioradialis) was measured and compared with the EMG of each muscle's MVC. A whole body index of shivering, determined from the mass-weighted intensity of shivering of each muscle group, was correlated with MR. After the initial few minutes of exposure, only the pectoralis major, rectus femoris, and biceps brachii continued to increase their intensity of shivering. Shivering intensity was higher in the central muscles, ranging from 5 to 16% of MVC compared with that in the peripheral muscles, which ranged from 1 to 4% of MVC. Shivering intensities were similar in the peripheral muscles for the LEAN and NORM groups, whereas differences occurred in the trunk muscles for the pectoralis major and rectus abdominis. The whole body index of shivering correlated significantly with each individual's increase in MR (r = 0.63-0.97).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mapping of resistance to the potato cyst nematode Globodera rostochiensis from the wild potato species Solanum vernei

A population of diploid potato (Solanum tuberosum) was used for the genetic analysis and mapping of a locus for resistance to the potato cyst nematode Globodera rostochiensis, introgressed from the wild potato species Solanum vernei. Resistance tests of 108 genotypes of a F₁ population revealed the presence of a single locus with a dominant allele for resistance to G. rostochiensis pathotype Ro1. This locus, designated GroV1, was located on chromosome 5 with RFLP markers. Fine-mapping was performed with RAPD and SCAR markers. The GroV1 locus was found in the same region of the potato genome as the S. tuberosum ssp. andigena H1 nematode resistance locus. Both resistance loci could not excluded to be allelic. The identification of markers flanking the GroV1 locus offers a valuable strategy for marker-assisted selection for introgression of this nematode resistance.Abbreviations BSA bulked segregant analysis - RAPD random-amplified polymorphic DNA - RFLP restriction fragment length polymorphism - SCAR sequence-characterized amplified region     

A genetic map of potato (Solanum tuberosum) integrating molecular markers,including transposons,and classical markers

A genetic map of potato (Solanum tuberosum L.) integrating molecular markers with morphological and isozyme markers was constructed using a backcross population of 67 diploid potato plants. A general method for map construction is described that differs from previous methods employed in potato and other outbreeding plants. First, separate maps for the female and male parents were constructed. The female map contained 132 markers, whereas the male map contained 138 markers. Second, on the basis of the markers in common the two integrated parental maps were combined into one with the computer programme JoinMap. This combined map consisted of 175 molecular markers, 10 morphological markers and 8 isozyme markers. Ninety-two of the molecular markers were derived from DNA sequences flanking either T-DNA inserts in potato or reintegrated maize transposable elements originating from these T-DNA constructs. Clusters of distorted segregation were found on chromosomes 1,2,8 and 11 for the male parent and chromosome 5 for both parents. The total length of the combined map is 1120 cM.