Towards an understanding of the Sarcostemma viminale (Asclepiadaceae) complex

LIEDE, S. & MEVE, U., 1993. Towards an understanding of the Sarcostemma viminale (Asclepiadaceae) complex. All names in Sarcostemma sensu Bullock (Asclepiadaceae, Asclepiadeae, Cynanchinae) are listed and their current status evaluated. Chromosome numbers are given for most taxa. The typification of S. viminale is clarified. A new subspecies of S. viminale is described from the Orange Free State, South Africa, and relationships of the Namaqualand/Namibia populations are discussed.     

Transport of Endocytosed Material Into Melanin Granules in Cultured Choroidal Melanocytes of Cattle—New Insights Into the Relationship of Melanosomes With Lysosomes

Cultured choroidal melanocytes from cattle were incubated with gold labeled albumin. After phagocytosis of the labeled protein, the label appeared inside the melanin granules, as was observed under the electron microscope. Melanin granules associated with gold particles were also exocytosed into the culture medium by the melanocytes. The results of this study show that endosomes or phagosomes are transported from the cell surface of a melanocyte to the melanin granules. Therefore, melanin granules are part of the lysosomal degradation pathway. The possibility that albumin is degraded by proteases present in lysosomes and melanosomes and that the tyrosine released during degradation is used as substrate by tyrosinase and thereby converted to melanin is discussed. The present study additionally shows that the choroidea of cattle can be used as a source for cell culture of melanocytes.     

Flexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosae

The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae , a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects.     

Nuclear DHT-Receptor in <Emphasis Type="Italic">Tfm</Emphasis>/<Emphasis Type="Italic">Y</Emphasis> Kidney Cell

OUR previous studies on the X-linked testicular feminization (Tfm) mutation¹ of the mouse^2–4 showed that the so-called cytosol and nuclear 5αx-dihydrotestosterone (DHT) receptor protein^5–7 might be a regulatory protein specified by the Tfm locus. The dual role of being a translational repressor in the cytoplasma and a mediator of hypertrophy in the nucleus was envisaged⁸. We found, however, another class of androgen-receptor in the polysome fraction of kidney proximal tubule cells which seems better qualified to be a translational regulator. Since a single gene locus specifies only one kind of polypeptide chain, we re-examined whether the cytosol and nuclear DHT-receptor protein underwent a true mutational change in Tfm/Y individuals.     

Mutational analysis of the <Emphasis Type="Italic">GLA</Emphasis> gene in Mexican families with Fabry disease

Fabry disease (FD) is a lysosomal storage disorder, which develops due to a deficiency in the hydrolytic enzyme, α-galactosidase A (α-Gal A). Alpha-Gal A hydrolyzes glycosphingolipid globotriaosylceramide (Gb3), and an α-Gal A deficiency leads to Gb3 accumulation in tissues and cells in the body. This pathology is likely to involve multiple systems, but it is generally considered to affect primarily vascular endothelium. In this study, we investigated mutations in the GLA gene, which encodes α-Gal A, in Mexican families with FD. We included seven probands with FD that carried known mutations. We analysed pedigrees of the probands, and performed molecular screening in 65 relatives with the potential of carrying a GLA mutation. Five mutations (P40S, IVS4 ⁺⁴, G328V, R363H, R404del) were detected in seven unrelated Mexican families with the classic FD phenotype. Of the 65 relatives examined, 42 (64.6%) had a GLA gene mutation. In summary, among seven Mexican probands with FD, 65 relatives were at risk of carrying a known GLA mutation, and molecular screening identified 42 individuals with the mutation. Thus, our findings showed that it is important to perform molecular analysis in families with FD to detect mutations and to provide accurate diagnoses for individuals that could be affected.     

A morphological, karyological and chemical study of the Apteranthes (Caralluma) europaea complex

The Apteranthes europaea complex (Apocynaceae–Asclepiadoideae–Ceropegieae–Stapeliinae) distributed from Morocco/southern Spain along the North African coast of the Mediterranean Sea up to Sinai, Negev and southern Jordan is studied with emphasis on stem and flower morphology by SEM, chromosome sizes and flavonoid compounds. Apteranthes europaea was found to be rich in rather uncommon flavone glycosides. Of these, luteolin 4'-neohesperidoside represents the major flavonoid of all samples; luteolin-3'- O -(6'- O -sinapoylglucoside)-4'- O -neohesperidoside and luteolin-3'- O -(6'- O -feruloylglucoside)-4'- O -neohesperidoside are reported here for the first time. Flavonol glycosides also occur, but in much smaller quantities. The different flower morphs, variation in stem and corolla epidermal structures, slight variations in the length of the 2 n  = 22 chromosomes and in quantitative flavonoid composition are taxonomically best reflected by subdividing the complex into a western var. europaea (Europe and Africa) and an eastern var. judaica (Sinai, Arabia).  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 419–432.