Sexual tetramorphism in Thymelaea hirsuta (Thymelaeaceae): morph ratios in open-pollinated progeny

Natural populations of Thymelaea hirsuta have previously been shown to comprise four distinct sexual morphs: males, females, protogynous individuals, i.e., first female then male, and protandrous individuals, i.e., first male then female. The objective of the present study has been to confirm the genetic basis of this sexual tetramorphism by quantifying morph ratios in the open-pollinated progeny of the four sexual phenotypes growing in a natural population. All four phenotypes were recovered in the progeny of each morph. All observed plants displayed a single sexual phenotype, thus confirming the genetic basis of the tetramorphism. The progeny sex ratios indicate that the genetic determination of sex in this species may be influenced by cytoplasmic factors, while the observed levels of functional female fertility suggest a near-dioecious system. The evolutionary significance of this tetramorphism as a transitional stage in the evolution of dioecy is discussed.     

Identification of new mutations in the Cu/Zn superoxide dismutase gene of patients with familial amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder affecting motor neurons. Although most cases of ALS are sporadic, approximately 10% are inherited as an autosomal dominant trait. Mutations in the Cu/Zn superoxide dismutase gene (SOD 1) are responsible for a fraction of familial ALS (FALS). Screening our FALS kindreds by SSCP, we have identified mutations in 15 families, of which 9 have not been previously reported. Two of the new mutations alter amino acids that have never been implicated in FALS. One of them affects a highly conserved amino acid involved in dimer contact, and the other one affects the active-site loop of the enzyme. These two mutations reduce significantly SOD 1 enzyme activity in lymphoblasts. Our results suggest that SOD 1 mutations are responsible for > or = 13% of FALS cases.     

Excess of deletions of maternal origin in the DiGeorge/Velo-cardio-facial syndromes. A study of 22 new patients and review of the literature

We have determined the parental origin of the deleted chromosome 22 in 29 cases of DiGeorge syndrome (DGS) using a CA-repeat mapping within the commonly deleted region, and in one other case by using a chromosome 22 short arm heteromorphism. The CA-repeat was informative in 21 out of 29 families studied and the deleted chromosome was of maternal origin in 16 cases (72%). When these data are pooled with recent results from the literature, 24 de novo DGS, velo-cardio-facial syndrome (VCFS) and isolated conotruncal cardiac disease deletions are found to be of maternal origin and 8 of paternal origin, yielding a ² of 8 with a probability level lower than 0.01. These data, and review of the literature on familial DGS/VCFS and isolated conotruncal cardiopathies suggest that there is a strong tendency for the 22q11.2 deletions to be of maternal origin.     

Intermolecular specificity of pancreatic lipase in the lipolysis of triacylglycerols containing phytanic acid.

Diffusional effects on two-substrate enzymic reactions mainly depend on the relative affinities of the enzyme for its two substrates. With two substrates of widely different affinities, diffusional limitations increase and decrease the half-maximal-activity concentration of the high-and low-affinity substrate respectively.     

Tryptophan pyrrolase in haem regulation. Experiments with administered haematin and the relationship between the haem saturation of tryptophan pyrrolase and the activity of 5-aminolaevulinate synthase in rat liver.

1. Administration of haematin to rats decreases 5-aminolaevulinate synthase activity in whole liver homogenates. 2. An inverse relationship between this decrease and the increase in saturation of apo-(tryptophan pyrrolase) with haem is observed during the initial phase of treatment with haematin. 3. Significant changes in both functions are caused by a 1 mg/kg dose of haematin, whereas the maximum effects are achieved by the 5 mg/kg dose. 4. Prevention by allopurinol of the conjugation of exogenously administered haematin with apo-(tryptophan pyrrolase) renders this haem available for further repression of 5 aminolaevulinate synthase. 5. The various aspects of the relationship between synthase activity and the haem saturation of tryptophan pyrrolase are discussed.     

Two small virus-specific polypeptides are produced during infection with Sindbis virus.

We have identified and characterized two small virus-specific polypeptides which are produced during infection of cells with Sindbis virus, but which are not incorporated into the mature virion. The larger of these is a glycoprotein with an approximate molecular weight of 9,800 and is found predominantly in the medium of infected cells. Three independent lines of evidence demonstrate conclusively that this 9,800-dalton glycoprotein is produced during the proteolytic conversion of the precursor polypeptide, PE2, to the virion glycoprotein E2. This small glycoprotein is therefore analogous to the virion glycoprotein E3 of the very closely related alphavirus, Semliki Forest virus. The 9,800-dalton glycoprotein of Sindbis virus, unlike the E3 glycoprotein of Semliki Forest virus, is not, however, present in the viral particle. The other virus-specific polypeptide is 4,200 daltons in size, does not appear to be a glycoprotein, and is neither incorporated into the mature virus nor released into the culture medium. The gene for this small polypeptide is present in the viral 26S mRNA (the mRNA which encodes all the viral structural polypeptides) and appears to be located in the portion of the mRNA which encodes the two viral glycoproteins. The possibility that this 4,200-dalton polypeptide functions as a signal peptide during the synthesis of the viral membrane glycoproteins is discussed.     

Effect of transient ischemia on monoamine levels in the cerebral cortex of gerbils

Abstract— Cortical monoamine changes during ischemic episodes of varied duration and their sequence of changes following cerebral reperfusion were studied in the gerbil. Forty-one percent of 280 animals exhibited signs of cerebral hemispheric ischemia (stroke) after unilateral common carotid artery occlusion. Norepinephrine (NE) levels decreased after 60 min in the occluded hemisphere of stroked animals but dopamine (DA) levels were unaltered. S-Hydroxytryptamine (5-HT) levels became bilaterally reduced in both stroked and non-stroked animals as soon as S min after occlusion. Upon reperfusion after periods of 30 or 60 min of occlusion there was a bilateral rebound increase of cortical NE and DA levels to well above control values in stroked and non-stroked animals. 5-HT levels remained reduced in both groups. Results suggest disorder of monoamine metabolism in ischemic brain which persists during the early reperfusion period, perhaps contributing to deficits in neurological function. Monoamine changes in contralateral non-ischemic hemispheres both during the occlusion and reperfusion periods are thought further evidence of diaschisis.