CHANGES IN PROTEIN BIOSYNTHESIS DURING GIBBERELLIC ACID INDUCED INDUCTION AND FORMATION OF ANTHERIDIUM IN THE FERN ANEMIA PHYLLITIDIS

Changes in protein biosynthesis have been studied during the induction and formation of antheridium in Anemia phyllitidis .
Based on incorporation of ¹⁴C-amino acid mixture into TCA precipitable material two distinct phases of accelerated protein biosynthesis were observed. First phase initiates at 4th day, while the second at 8th day of development. The first phase is likely associated with antheridium induction and second with spermatogenesis. From electrophoretic pattern of proteins on stained acrylamid gels and from radioactivity profiles of labelled proteins distinct quantitative differences between vegetative and reproductive prothalli were observed at different stages of antheridial development. Radioactivity profiles reveal characteristic pattern of each stage of antheridial differentiation.     

Changes in the Organic Acid Content of some Cultivated Plants Induced by Mineral Ion Deficiency

Four plant species (Zea mays, Lolium italicum, Phaseolus vulgaris,and Pisum sativum) were grown either with full nutrient supplyor with calcium, potassium, or nitrogen deficiency. After 4–6weeks the shoots were analysed for their content of K⁺, Ca²⁺,Mg²⁺, and Na⁺, of total anions, and of organic acids. The qualitativepattern of organic acid components, characteristic of each species,remained, with few exceptions, unchanged by deficiency treatments.Striking differences were detected in the total acid contentand in the quantities of the respective main organic acid components,especially in potassium-deficient plants. These changes showedstrong correlations with alterations of cation excess and demonstratethat aconitate in Zea mays, malonate in Phaseolus vulgaris,and citrate in Pisum sativum contribute to charge balance.     

Noradrenaline and “Chemical Coding” of Hypothalamic Neurones

FIRING rates of single neurones in the “feeding system”—the perifornical and ventromedial areas of the hypothalamus—are altered by the systemic administration of an anorexigenic agent, such as amphetamine or glucose^1–4. Using the micro-iontophoretic technique which involves releasing chemicals directly on individual neurones, Oomura et al. confirmed that glucose can alter the spontaneous firing rates of some neurones in the hypothalamus of the rat⁵. We wish to report that micro-iontophoretic applications of glucose, amphetamine and noradrenaline to hypothalamic neurones yield a pattern of results not readily reconcilable with the current views of the role of adrenergic substances as “transmitters” in the regulation of hypothalamic feeding function.     

A paradox survival – report of a repaired syn vivo perforation in a nautiloid phragmocone

The nautiloid Trocholites depressus (Eichwald, 1840) from the Lasnamägi regional stage (Darrivillian, Middle Ordovician) of Vaike Pakri Island (North-West Estonia) is the only known ectocochleate cephalopod that survived and healed a perforation of the phragmocone. Two chambers of the specimen were broken during its lifetime. The injury is located on the venter of the conch directly above the peristomal opening of the body chamber. It is reconstructed that the peristomal mantle tissue carried out an initial sealing of the injured chambers. The complete calcified sealing and compensation of the irregular shell surface started late with the overgrowth of the septa of the preceding whorl. The position and diameter of the siphuncle were not disturbed by the regeneration showing that these characters allowed a low phenotypic variability. Despite the trauma in the midlife growth history of this specimen, it appears to have reached maturity.     

The Lek System in Uganda Kob Antelope

The tradition with which both male and female Uganda kob returnto permanently located territorial breeding grounds (TG's orleks), along with the dispersion of individuals in relationshipto a home TG and morphological variation between individualsassociated with different TG's, indicates that the total populationof kob in the Toro Game Reserve and its vicinity is subdividedinto relatively closed breeding units. Mathematical analysesof linear body measurements show significant differences inmorphological features between three demes, not only in averagesbut also in the inter-relatedness of body characteristics, suggestingan underlying genetic integrity within demes. Interdemic geneflow through individuals appears to be inconsequential, butthere may be significant gene flow through the formation oftemporary TG's. Altruistic behavior among territorial males may contribute tokinship selection, and the individual kob behavior in responseto predation suggests that altruism may have a bearing on theregulation of predation. The lek system of social organizationmay be significant in maintaining genetic heterogeneity in thekob antelope, which lives in geographically isolated populationsthroughout its range.     

Evidence For the Presence of A Cdc2-Like Protein Kinase In the Dinoflagellate Crypthecodinium Cohnii

ABSTRACT. The unusual nature of mitosis and ancestral organization of the dinoflagellate nucleus prompted the question of whether the cdc 2-like histone H1 kinase, a presumed ubiquitous cell cycle regulator in eukaryotes, is present in these primitive organisms. Western blotting of Crypthecodinium cohnii protein extracts using antibody against the Pro-Ser-Thr-Ala-Ile-Arg-Glu (=PSTAIRE) amino acid sequence motif, conserved in all cdc 2 homologues known, revealed one prominent band corresponding to a protein with an apparent relative molecular weight ≈ 34,000, identical in mobility to that from HeLa cells and Physarum polycephalum , higher and lower eukaryotic controls, respectively. Incubation of C. cohnii cell lysates with p13 ^{suc 1}-sepharose beads, which preferentially, though not exclusively, bind p34 ^{cdc 2}, resulted in precipitation of a 34-kDa protein which was reactive with anti-PSTAIRE antibody, selectively competed for by the PSTAIRE peptide and able to phosphorylate histone H1 in vitro. We conclude that the dinoflagellate C. cohnii contains a protein very similar to the cdc 2 gene product from fission yeast and its homologues in all eukaryotes studied thus far.     

Ultrastructure and Organization of the Cytoskeleton in Oxymonas, an Intestinal Flagellate of Termites

ABSTRACT. Oxymonas has the characteristic structures and organization of other oxymonads including two separated pairs of basal bodies/flagella, a preaxostylar lamina, a paracrystalline axostyle, and an absence of mitochondria and Golgi. Like other Oxymonadinae genera it possesses a long proboscis, the rostellum which is terminated by the holdfast. Like the genera Pyrsonympha and Streblomastix, Oxymonas possesses a holdfast which permits it to attach to the cuticle of the termite hind-gut. This holdfast is subdivided into rhizoids and is filled with microfilaments. The rostellum is variable in length and contains two distinct microtubular bundles. One bundle is composed of convoluted microtubular ribbons which originate at the base of the holdfast and extend posteriorly along the rostellum and before penetrating into the cell body. The second bundle is composed of flexuous free microtubules which originate at different levels of the rostellum, increasing in number from top to base. They occupy the axial part of the rostellum and incorporate into the axostylar rows at the basal body/flagellar level. Microtubules of the paracrystalline axostyle are cross-linked by bridges forming parallel rows like in the contractile axostyles of other oxymonads such as Pyrsonympha and Saccinobaculus . Most of the microtubules of the axostyle originate at the flagellar/preaxostylar level but some originate from the axial flexous free microtubules of the rostellum, as indicated above. The possibility of an extension/retraction of the rostellum, suggested by other authors, is discussed.     

Involvement of trichothecenes in fusarioses of wheat, barley and maize evaluated by gene disruption of the trichodiene synthase (Tri5) gene in three field isolates of different chemotype and virulence

Fusarium graminearum is the main causative agent of Fusarium head blight on small grain cereals and of ear rot on maize. The disease leads to dramatic yield losses and to an accumulation of mycotoxins. The most dominant F. graminearum mycotoxins are the trichothecenes, with deoxynivalenol and nivalenol being the most prevalent derivatives. To investigate the involvement of trichothecenes in the virulence of the pathogen, the gene coding for the initial enzyme of the trichothecene pathway was disrupted in three field isolates, differing in chemotype and in virulence. From each isolate three individual disruption mutants were tested for their virulence on wheat, barley and maize. Despite the different initial virulence of the three wild-type progenitor strains on wheat, all disruption mutants caused disease symptoms on the inoculated spikelet, but the symptoms did not spread into other spikelets. On barley, the trichothecene deficient mutants showed no significant difference compared to the wild-type strains: all were equally aggressive. On maize, mutants derived from the NIV-producing strain caused less disease than their wild-type progenitor strain, while mutants derived from DON-producing strains caused the same level of disease as their progenitor strains. These data demonstrate that trichothecenes influence the virulence of F. graminearum in a highly complex manner, which is strongly host as well as moderately chemotype specific.     

Comparative Binding of 125I-and 99mTc-Labeled Native and Glycated Low-Density Lipoprotein to Human Microvascular Endothelial Cells-Potential for Atherosclerosis Imaging?

Native (n), glycated (g), and glycoxidated (go) low-density lipoproteins (LDL) were labeled with ¹²⁵I or ^99mTc, and the labeling efficiency and binding were assessed for potential use of these LDL compounds in imaging analysis of atherosclerotic lesions (PPAR-γ receptors) by determining the number of specific receptors for nLDL, gLDL or goLDL on human microvascular endothelial cells as well as the K_D s using either ¹²⁵I-or ^99mTc-labeled LDLs. The specific activity of labeled gLDL and goLDL was much higher (for goLDL 20 times higher) than that of nLDL. Gel filtration of labeled LDLs revealed, however, that ^99mTc–g/goLDL is significantly degraded by the labeling reaction. No fragmentation was observed for ^99mTc-nLDL and all the ¹²⁵I-labeled LDL forms. Binding studies using both ¹²⁵I-and ^99mTc-nLDL indicated a weak binding affinity (K_D 10^{? 7}mol/L) to human microvascular endothelial cells. The binding affinity of ¹²⁵I-g/goLDL to these cells was significantly higher (K_D 10^{? 9}mol/L) and could be increased further by preactivation of the endothelial cells using TNFα. Incubation with ^99mTc-goLDL, however, did not result in specific binding of the ligand, possibly as a consequence of the fragmentation of the lipoprotein during the labeling. Scatchard transformation of the binding data with ^99mTc-gLDL revealed the presence of only a few binding sites. This was in contrast to the results obtained with ¹²⁵I-labeled gLDL, which revealed a much higher membrane density of scavenger receptors for this ligand. We conclude that for in vitro binding studies as well as for potential in vivo imaging, only ¹²⁵I-labeled goLDL should be used, whereas nLDL may be applied as ¹²⁵I-or ^99mTc-labeled ligand.