Delimitation of morphologically similar sponge crab species of the genus Pseudodromia (Crustacea, Decapoda, Dromiidae) from South Africa

Stewart, B. A., Gouws, G., Daniels, S. R. & Matthee, C. A. (2004). Delimitation of morphologically similar sponge crab species of the genus Pseudodromia (Crustacea, Decapoda, Dromiidae) from South Africa. — Zoologica Scripta , 33 , 45–55.
Presently, three Pseudodromia sponge crab species are recognized, all of which are endemic to the continental shelf off the coast of South Africa. Two of these differ only in the morphology of their rostral teeth, making them difficult to distinguish, and can thus be considered as cryptic species. In addition they have very similar distribution ranges, thus raising doubts as to their specific status. Discriminant function analysis of morphometric data, differentiation at 10 allozyme loci, and sequence data derived from the 12S rRNA mitochondrial gene were used to test whether specimens identified as P. latens and P. rotunda are morphological forms of a single, widespread species, or represent two, distinct, reproductively isolated species, and to establish whether these two taxa are sister species, and thus form a monophyletic entity. The presence of fixed allele differences at three, and strong genetic heterogeneity at five other allozyme loci, indicating no gene flow occurring between sympatric populations, as well as the relatively high degree of 12S rRNA and allozyme genetic differentiation observed, supported the recognition of P. latens and P. rotunda as separate species. The 12S rRNA topology suggested that the genus Pseudodromia , as presently constituted, is paraphyletic, thus inferring that the morphological characters used to define this taxon might not be useful for phylogenetic inferences. It was concluded that in view of the uncertainties raised regarding the designation and composition of certain genera within the family Dromiidae, further rigorous analyses of morphological and genetic data are needed to further our understanding of the taxonomy of the sponge crabs.     

Intrinsic potential for high fetal hemoglobin production in a Druze family with β-thalassemia is due to an unlinked genetic determinant

Summary The mechanism for elevated production of fetal hemoglobin (Hb F) in a Druze patient with °-thalassemia intermedia was investigated. Heterozygous family members exhibited normal Hb F levels, suggesting that the increase in -gene expression in the propositus may be partly due to anemic stress. Erythroid progenitors of these family members cultured in vitro [burst forming units (erythroid); (BFUe)] showed elevated synthesis of Hb F, indicating the existence of a genetically determined intrinsic capacity for high Hb F production in this family. The propositus was found to be homozygous for a IVS2-position 1 mutation, on the background of Mediterranean haplotype I, which is not known to be linked to high Hb F production. Moreover, extensive molecular studies of the -globin gene cluster, including sequence analysis of the promoter regions of the -globin genes, did not reveal any cisacting mechanism that could account for the high Hb F production in the propositus. A young niece of the propositus with °-thalassemia major was recently discovered, who was homozygous for the same -globin allele and haplotype as the propositus. However, unlike her uncle, she does not have a high Hb F level and presents with a severe clinical course. Her inability to produce high Hb F suggests that the genetic determinant for increased -gene expression in the propositus is unlinked to the -globin gene cluster.     

Isolation and characteristics of Thiopedia rosea (neotype)

Four new strains of Thiopedia rosea were isolated in pure culture from blooms of platelet-forming purple sulfur bacteria in the top layers of the anoxic hypolimnia of two freshwater lakes. Individual cells of the new strains as well as of T. rosea strain 4211 were spherical to oval, nonmotile and contained gas vesicles in the central part. The predominant photosynthetic pigments were bacteriochlorophyll a and okenone. All strains were strictly anaerobic and obligately phototrophic. Optimal growth occurred at low light intensities of 100 E · m^-2 s^-1 (tungsten lamp); intensities above 150 E · m^-2 s^-1 inhibited growth completely. Photoautotrophic growth was possible at sulfide concentrations up to 0.6 mM; higher concentrations were inhibitory. Acetate, butyrate and valerate supported photoorganotrophic growth in the presence of bicarbonate and sulfide concentrations below 1 mM. Sulfide was required as a source of cellular sulfur because assimilatory sulfate reduction is lacking. All strains were assigned to the species Thiopedia rosea with strain 4211 as a neotype.Dedicated to Prof. Dr. H. G. Schlegel on the occasion of his 66th birthday     

The phytate and mineral content of some cereals,cereal products,legumes, legume products,snack bars,and nuts available in New Zealand

Analyses for phytate by an indirect precipitation method and for the minerals calcium (Ca), zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) by atomic absorption spectrophotometry were carried out on 100 foods available in New Zealand. Foods with 1% phytate (dry weight basis) included untoasted muesli, rolled oats, wheat germ, wheat bran, soybean, and some soy products. Most breads contained between 0.35 and 0.60% phytate; legumes on average had 0.62% phytate, as did snack bars. There was a wide variation in Ca and Zn contents: There was a tenfold variation in Ca content among the legume products, whereas there was a seventyfold variation in Zn content among the cereals. The phytate: Zn molar ratio, which is presumed to indicate the biovailability of Zn, was above 20∶1 for two-thirds of the cereals and almost all of the snack bars; it was above 15∶1 for one-third of the breads, almost all of the legumes, and half of the legume products. These high phytate: Zn molar ratios, as well as some Ca: phytate molar ratios above 6∶1, indicate that there might be a reduced biovailability of Zn in many of the foods analyzed in this study.     

Selection for increased abdominal bristle number in Drosophila melanogaster with concurrent irradiation

Summary Replicate lines, each, with one hundred pairs of parents selected at 50% intensity, were derived from an inbred line. For twenty generations three lines were selected without irradiation and five with 1000 r X-rays per generation given to both females and males. After adjustment for level of crowding in the cultures, the final mean was 1.3 bristles higher in females and 1.0 bristles higher in males in the irradiated lines than in the unirradiated lines. In terms of phenotypic standard deviations in each sex in the base population, these total responses were 0.74 and 0.59 respectively. Radiation can induce mutations useful in increasing responses in selection programmes, but the average response attributable to radiation is small, and heterogeneity between replicate lines is to be expected.This work was carried out while B. H. was on leave from the New South Wales Department of Agriculture, and held a Commonwealth Research Studentship. Our thanks to Robin Hall and Tricia Brown for technical assistance, to Dr. B. L. Sheldon, C.S.I.R.O. Division of Animal Genetics, for providing the inbred line, and to the Radio-Therapy Unit, Royal Prince Alfred Hospital, for the use of their equipment.     

A Gene for Autosomal Dominant Congenital Nystagmus Localizes to 6p12

Congenital nystagmus is an idiopathic disorder characterized by bilateral ocular oscillations usually manifest during infancy. Vision is typically decreased due to slippage of images across the fovea. As such, visual acuity correlates with nystagmus intensity, which is the amplitude and frequency of eye movements at a given position of gaze. X-linked, autosomal dominant, and autosomal recessive pedigrees have been described, but no mapping studies have been published. We recently described a large pedigree with autosomal dominant congenital nystagmus. A genome-wide search resulted in six markers on 6p linked by two-point analysis at θ = 0 (D6S459, D6S452, D6S465, FTHP1, D6S257, D6S430). Haplotype analysis localizes the gene for autosomal dominant congenital motor nystagmus to an 18-cM region between D6S271 and D6S455.     

Hyperpolarization-activated inward chloride current in protoplasts from suspension-cultured carrot cells

Summary Plasmalemmal ionic currents from enzymatically-isolated protoplasts of suspension-cultured carrot cells were investigated by patch-clamp techniques. Among other currents, a novel hyperpolarization-activated, inwardly-rectifying, whole-cell current was observed. The activation of this current was fast in onset, and for large hyperpolarizations a characteristic, rapid voltage-dependent inactivation was seen. Ion substitution experiments indicate that this inward current was due mainly to efflux of chloride ions. No dependence on either internal or external calcium was found, and internal MgATP was not necessary. Surprisingly, zinc did not block this current. In hyperpolarized outside-out patches, inward single-channel chloride currents having an elementary conductance of ca. 100 pS were observed. The open probability increased with hyperpolarization. Similar single-channel currents were activated by slight negative pressure applied to the pipette. These chloride currents could contribute both to the control of membrane potential and in the regulation of osmotic balance in carrot cells.Abbreviations BAPTA 1,2-bis (2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - E_x Nernst equilibrium potential for ion x - NMDG N-methyl-D-glucamine - PMSF phenylmethylsulfonyl fluoride