Karyomorphology of six taxa in Chrysanthemum sensu lato (Anthemideae) in Egypt and their genetic relationships by Giemsa C‐banding

Abstract Giemsa C‐banding was applied to the chromosome complements of six diploid species belonging to six genera in Chrysanthemum sensu lato (Anthemideae) distributed in Egypt. Four types of C‐banding distribution were observed in the taxa as follows: (i) negative C‐banding in Anacyclus monanthos (L.) Thell.; (ii) all bands in terminal regions in Achillea fragrantissima (Forssk.) Sch. Bip, which showed 32 bands on 18 chromosomes; (iii) all eight bands at centromeric regions on eight chromosomes in Matricaria recutita L.; and (iv) bands at terminal and centromeric regions in Brocchia cinerea Vis. (12 terminal and six centromeric bands on 12 chromosomes), Cotula barbata DC. (four terminal, six centromeric, and eight short arm bands on 16 chromosomes), and Glebionis coronaria (L.) Cass. ex Spach. (eight terminal on the short arms and four large bands in centromeric regions on 12 chromosomes).     

The Phlesirtes complex (Orthoptera,Tettigoniidae, Conocephalinae,Conocephalini) reviewed: integrating morphological,molecular, chromosomal and bioacoustic data

The tettigoniid genus Phlesirtes Bolivar and its allies are reviewed. Morphological, ecological and molecular data prompt the erection of the new genus Chortoscirtes gen.n. with type species Xiphidion meruense Sjöstedt. The genera Phlesirtes, Chortoscirtes, Karniella and Naskreckiella are characterized by morphological characters supported by molecular, acoustic, ecological and chromosomal data. Four species, Chortoscirtes pseudomeruensis sp.n. , C. masaicus sp.n. , C. puguensis sp.n. and C. serengeti sp.n. , are described from localities in northern and coastal Tanzania and one Karniella, K. crassicerca sp.n. , is described from Uganda. The following comb n. are proposed: Phlesirtes kibonotensis (Sjöstedt) and Phlesirtes kilimandjaricus (Sjöstedt). Subtribal status is proposed for the four investigated African genera. A key to the Chortoscirtes species is provided.     

TRPV1 expression and activity during retinoic acid-induced neuronal differentiation

The transient receptor potential vanilloid subtype 1 (TRPV1) is a Ca²⁺-permeable channel primarily expressed in dorsal root ganglion neurons. Besides its function in thermogenic nociception and neurogenic inflammation, TRPV1 is involved in cell migration, cytoskeleton re-organisation and in neuronal guidance. To explore the TRPV1 level and activity during conditions for neuronal maturation, TRPV1-expressing SHSY5Y neuroblastoma cells were differentiated into a neuronal phenotype using all-trans-retinoic acid (RA). We show that RA highly up-regulated the total and cell surface TRPV1 protein expression but the TRPV1 mRNA level was unaffected. The up-regulated receptors were localised to the cell bodies and the developed neurites. Furthermore, RA increased both the basal intracellular free Ca²⁺ concentration by 30% as well as the relative capsaicin-induced Ca²⁺ influx. The results show that TRPV1 protein expression increases during RA-induced differentiation in vitro, which generates an altered intracellular Ca²⁺ homeostasis.     

Relation among plant growth,carbohydrates and flowering time in the Arabidopsis Landsberg erecta × Kondara recombinant inbred line population

Arabidopsis thaliana natural variation was used to study plant performance viewed as the accumulation of photo‐assimilates, their allocation and storage, in relation to other growth‐related features and flowering‐related traits. Quantitative trait locus (QTL) analysis using recombinant inbred lines derived from the cross between Landsberg erecta (originating from Poland) and Kondara (originating from Tajikistan) grown on hydroponics, revealed QTLs for the different aspects of plant growth‐related traits, sugar and starch contents and flowering‐related traits. Co‐locations of QTLs for these different aspects were detected at different regions, mainly at the ER locus; the top of chromosomes 3, 4 and 5; and the bottom of chromosome 5. Increased plant growth was associated with early flowering and leaf transitory starch, and correlated negatively with the levels of soluble sugar at early phases of development. From the significant correlations and the co‐locations of the QTLs for these aspects, we conclude that there is a complex relationship between plant growth‐related traits, carbohydrate content and flowering‐related traits.     

Surface Anionic Groups in Symbiote-Bearing and Symbiote-Free Strains of Crithidia deanei1

The surface anionic groups of symbiote-bearing and symbiote-free strains of Crithidia deanei were compared by determining cellular electrophoretic mobility, by ultrastructural cytochemistry, and by identification of sialic acids by thin-layer and gasliquid chromatography. Symbiote-free Crithidia deanei has a highly negative surface charge (-0.9984 μm?s^-1? V^-1? cm), which is slightly reduced (-0.8527 μm?s^-1? V^-1? cm) by the presence of the endosymbiote. Treatment of both strains of C. deanei with neuraminidase decreased significantly the electrophoretic mobility of cells toward the cathodic pole, indicating the existence of exposed sialic acid residues responsible for the negative charge on the protozoan cell surface. Thin-layer and gas-liquid chromatography showed that N-glycolyl- and N-acetylneuraminic acids were present in both strains of C. deanei.     

Models for coupling of salt and water transport; Proximal tubular reabsorption in Necturus kidney

Models for coupling of salt and water transport are developed with two important assumptions appropriate for leaky epithelia. (a) The tight junction is permeable to both sale and water. (b) Active Na transport into the lateral speces is assumed to occur uniformly along the length of the channel. The proposed models deal specifically with the intraepithelial mechanism of proximal tubular resbsorption in the Necturus kidney although they have implications for epithelial transport in the gallbladder and small intestine as well. The first model (continuous version) is similar to the standing gradient model devised by Diamond and Bossert but used different boundary conditions. In contrast to Diamond and Bossert's model, the predicted concentration profiles are relatively flat with no sizable gradients along the interspace. The second model (compartment version) expands Curran's model of epithelial salt and water transport by including additional compartments and considering both electrical and chemical driving forces for individual Na and Cl ions as well as hydraulic and osmotic driving forces for water. In both models, ion and water fluxes are investigated as a function of the transport parameters. The behavior of the models is consistent with previously suggested mechanisms for the control of net transport, particularly during saline diuresis. Under all conditions the predicted ratio of net solute to solvent flux, or emergent concentration, deviates from exact isotonicity (except when the basement membrane has an appreciable salt reflection coefficient). However, the degree of hypertonicity may be small enough to be experimentally indistinguishable from isotonic transport.     

Polymorphism of the Thymidylate Synthase Gene of Pneumocystis carinii from Different Host Species

Pneumocystis carinii is an opportunistic agent found in the lung of various mammals which often causes severe pneumonia in immunocompromised humans, especially in AIDS patients. In the past several years significant additions have been made to the collection of knowledge we have concerning the genetic diversity of P. carinii. These additions provide new understanding of Pneumocystis transmission and the effect of possible reservoirs of Pneumocystis in the various species. In this study, a 400-bp fragment of the thymidylate synthase (TS) gene of P. carinii has been amplified by PCR from 43 parasite isolates obtained from 4 mammalian host species: rat, mouse, rabbit and human. A probe selected from the TS gene sequence of rat-derived P. carinii was hybridized with the amplified products from rat- and mouse-derived P. carinii, but not with rabbit or human P. carinii DNA. Restriction profiles were performed on amplified fragments from all isolates, and the 4 nucleotide sequences of the TS gene fragment amplifed from rat, mouse, rabbit and human P. carinii were determined. Differences were detected in the gene fragment in P. carinii isolates from the 4 host species; however no difference was revealed in P. carinii isolates within a single host species, whatever the host strain or its geographic origin. Thus, the sequence differences of the P. carinii TS gene appeared as host-species specific. A specific probe which recognized all human P. carinii isolates was defined.     

Catabolism of Tryptophan by Trypanosoma evansi

ABSTRACT. Trypanosoma brucei gambiense , which causes human African trypanosomiasis, catabolizes the aromatic amino acid tryptophan via an initial aminotransferase catalyzed reaction to form several indole end products, which have been suggested to contribute to the pathogenesis of trypanosomiasis. To determine if this same pathway exists in T. evansi , the closely related trypanosome pathogen of domestic animals, tryptophan catabolism was examined in vitro and in vivo. As is the case with human African trypanosomes, T. evansi catabolized tryptophan to form indole-3-pyruvic acid and smaller amounts of indole-3-acetic acid and indole-3-lactic acid. Large concentrations of indole-3-pyruvic acid are excreted in urine of trypanosome-infected mice. However, indole-3-ethanol could not be detected in incubates of T. evansi or T. b. gambiense , even though the latter species had previously been reported to form this neutral metabolite. A new, previously unreported tryptophan metabolite was isolated and partially characterized from incubates of T. evansi and T. b. gambiense. Although the functional significance of tryptophan catabolism to trypanosomatids remains obscure, the pathway is quantitatively significant in all species examined thus far.     

Influence of Exogenous Hormones on Somatic Embryogenesis in Hevea brasiliensis

Generating somatic embryos from the inner teguments of Heveaseeds is difficult. Like other ligneous plants, the rubber-treeis generally considered to be recalcitrant with regard to somaticembryogenesis. In this paper we show that when conventionallyused amounts of both 3, 4-dichlorophenoxyacetic acid (3, 4-D)and benzylaminopurine (BAP) are reduced by 2–4 times andwhen the length of exposure to these hormones is also reduced,the embryogenic capacity of calli increases without affectingcallogenesis. The germination of several embryos and plantletswas obtained. We conclude that an excess of auxin and cytokininin the medium, even of a weak auxin such as 3, 4-D, and theprolonged exposure to these hormones suppress the embryogeniccapacity of the callus. Hevea brasiliensis, rubber-tree, somatic embryogenesis, hormones