Hypoglycemic action of the pectin present in the juice of the inflorescence stalk of plantain (Musa sapientum)—Mechanism of action

The pectin isolated from the juice of the inflorescence stalk of plantain (Musa sapientum) has been found to show significant hypoglycemic effect both in normoglycemic and alloxan diabetic rats. After its administration at a dose of 20mg/100g body weight, there was increase in the concentration of hepatic glycogen, increased glycogenesis as evident from the increased activity of glycogen synthetase and in normoglycemic rats increased incorporation of labelled glucose into hepatic glycogen. Glycogenolysis and glyconeogenesis were lower as was evident from the decreased activity of glycogen phosphorylase and gluconeogenic enzymes.     

A nucleotide substitution in one of the β-tubulin genes of Trichoderma viride confers resistance to the antimitotic drug methyl benzimidazole-2-yl-carbamate

We characterized a Trichoderma viride strain that is resistant to the antimitotic drug methyl benzimidazole-2-yl-carbamate (MBC). This species has two β-tubulin genes (tub1 and tub2) and by reverse genetics we showed that a mutation in the tub2 gene confers MBC resistance in this strain. Comparison of the tub2 sequence of the mutant strain with that of the wild type revealed that a single amino acid substitution of tyrosine for histidine at position 6 is responsible for the MBC tolerance. Furthermore, we showed that this gene can be used as a homologous dominant selectable marker in T. viride transformation. Both tubulin genes were completely sequenced. They differ by 48 residues and the degree of identity between their deduced amino acid sequences is 86.3%.     

Inhibition of hexose transport in the human erythrocyte by 5, 5′-dithiobis(2-nitrobenzoic acid): Role of an exofacial carrier sulfhydryl group

Summary The sulfhydryl reagent 5, 5-dithiobis (2-nitrobenzoic acid) (DTNB) was used to study the functional role of an exofacial sulfhydryl group on the human erythrocyte hexose carrier. Above 1mm DTNB rapidly inhibited erythrocyte 3-O-methylglucose influx, but only to about half of control rates. Efflux was also inhibited, but to a lesser extent. Uptake inhibition was completely reversed by incubation and washing with 10mm cysteine, whereas it was only partially reduced by washing in buffer alone, suggesting both covalent and noncovalent interactions. The covalent thiol-reversible reaction of DTNB occurred on the exofacial carrier, since (i) penetration of DTNB into cells was minimal, (ii) blockade of potential uptake via the anion transporter did not affect DTNB-induced hexose transport inhibition, and (iii) DTNB protected from transport inhibition by the impermeant sulfhydryl reagent glutathione-maleimide-I. Maltose at 120mm accelerated the covalent transport inhibition induced by DTNB, whereas 6.5 m cytochalasin B had the opposite effect, indicating under the one-site carrier model that the reactive sulfhydryl is on the outward-facing carrier but not in the substrate-binding site. In contrast to glutathione-maleimide-I, however, DTNB did not restrict the ability of the carrier to reorient inwardly, since it did not affect equilibrium cytochalasin B binding. Thus, carrier conformation determines exposure of the exofacial carrier sulfydryl, but reaction of this group may not always lock the carrier in an outward-facing conformation.     

Characterization of a new sulfhydryl group reagent: 6,6′-Diselenobis-(3-Nitrobenzoic acid), a selenium analog of Ellman's reagent

A new reagent, 6,6′-diselenobis-(3-nitrobenzoic acid) (DSNB) has been synthesized and is shown to be useful for quantitative estimation of sulfhydryl groups in proteins. This reagent, which is a selenium analog of Ellman's reagent, reacts specifically and quantitatively with thiol groups of proteins to yield a selenenyl sulfide and the dianion of 3-nitro-6-selenobenzoic acid. The molar absorption coefficient of the chromophoric dianion is 10,000 at 432 nm in dilute aqueous solutions. The titration can best be performed at pH 8.20 where >98% of 3-nitro-6-selenobenzoic acid is in the form of the intensely colored dianion. Sulfhydryl content determinations by this reagent of reduced and denatured ribonuclease, reduced and denatured lysozyme, native papain, and native and denatured thymidylate synthetase are compared with those from corresponding 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) titrations. The reagent was found to inactivate thymidylate synthetase, an enzyme with essential sulfhydryl groups. Unlike DTNB which undergoes alkaline decomposition of pH values greater than 9, DSNB was found to be stable to hydrolysis, even in 0.05 m NaOH.     

Untangling the Echiniscus Gordian knot: paraphyly of the “arctomys group” (Heterotardigrada: Echiniscidae)

The genus Echiniscus C.A.S. Schultze, 1840, one of the earliest established and speciose tardigrade genera, has been hypothesized to be polyphyletic. Moreover, the presence or absence of trunk appendages, the type of cuticular sculpturing and body colour have been argued to hold taxonomic significance at the genus level in Echiniscus-line taxa. Here, by combining morphological and genetic analyses, we demonstrate that the so-called “arctomys group”, i.e. Echiniscus spp. lacking trunk appendages, comprises numerous separate evolutionary lineages within the family Echiniscidae. As a result, we erect five new echiniscid genera: Barbaria gen. nov. , presumably of Neotropical (Gondwanan) origin, previously classified as the Echiniscus bigranulatus group; the pantropical and subtropical Kristenseniscus gen. nov. (the tessellatus group), characterized by a peculiar subdivision of dorsal plates; Claxtonia gen. nov. (the wendti group), with large and evident endocuticular pillars in the form of polygons; Nebularmis gen. nov. (the reticulatus group), with an elusive dorsal sculpturing; and Viridiscus gen. nov. (the viridis group), with body colour ranging from light green through brownish to even almost black. Additionally, we briefly address appendaged Echiniscus s.s. and divide the genus into several groups based on dorsal plate sculpturing and suggest that these could also represent separate supraspecific entities.     

3-(3-Phenoxybenzyl)amino-β-carboline: a novel antitumor drug targeting α-tubulin

3-(3-Phenoxybenzyl)amino-β-carboline 2h showed extremely-high activity; the IC₅₀ value was 0.074 μM. To verify 2h-induced cell death types, we observed the chromatin condensation, the DNA fragmentation and activated caspase-3 using Hoechst 33342, agarose electrophoresis and western blot, and suggesting 2h-induced cell death type was apoptosis. Flow cytometry showed that 2h-treated cell was induced SubG1 cell population after G2/M cell cycle arrest. In addition, using affinity chromatography and peptide mass fingerprinting, we found that interacting protein with this compound was α-tubulin protein.     

Mechanism of action of thrombin on fibrinogen: Reaction of the N-terminal CNBr fragment from the Bβ chain of bovine fibrinogen with bovine thrombin

The N-terminal cyanogen bromide fragment from the Bβ chain of bovine fibrinogen was isolated, and its molecular weight was estimated to be approximately 14,000–15,500. The ratio of the Michaelis-Menten constants, $\text{k}{}_{\mathrm{<mtext>cat</mtext>}}\text{K}{}_{\mathrm{m}}$, for its hydrolysis by bovine thrombin was found to be 3 × 10^?7 [(NIH unit/liter)s]^?1, indicating that the Bβ fragment is a poor substrate for thrombin compared to the corresponding Aα chain fragment. This value of $\text{k}{}_{\mathrm{<mtext>cat</mtext>}}\text{K}{}_{\mathrm{m}}$ is too small to account for the rate of release of fibrinopeptide B from fibrinogen by thrombin. It is suggested that, while the Aα chain contains all of the amino acid residues necessary to interact with thrombin, the Bβ chain does not; i.e., some of the binding sites that are used in the hydrolysis of the Bβ chain are assumed to be located on either the α or γ chains of fibrinogen. An alternative hypothesis is that, after the Bβ chain fragment is removed from the fibrinogen molecule, it does not have the proper conformation to be hydrolyzed by thrombin.     

Fine structure of the midgut of Sinopanorpa tincta (Navás) (Mecoptera: Panorpidae)

Fine structure of the midgut and degeneration of the midgut epithelium of the scorpionfly Sinopanorpa tincta (Navás) adults were investigated using light microscopy and scanning and transmission electron microscopy. The results show that the tubular midgut lacks gastric caeca and is composed of an outer longitudinal and an inner circular muscle layer, a basal lamina, an epithelium and a lumen from the outside to inside. A peritrophic membrane was not found in the lumen. A mass of nodules was observed on the surface of the basal lamina. Three types of cells were recognized in the epithelium: digestive, secretory, and regenerative cells. The digestive cells contain irregular-shaped infoldings in the basal membrane and two types of microvilli in the apical membrane. The secretory cells are characterized by irregular shape and large quantities of secretory granules in the basal cytoplasm. The regenerative cells are triangular in shape and distributed only in the nodules. The epithelial cells are degenerated through programmed cell-death mechanisms (apoptosis and necrosis). The type, function, and degeneration of the epithelial cells of the midgut are briefly discussed.     

Role of the guanidine group in the N-terminal fragment of PTH(1–11)

A series of PTH hybrids containing a diamine [NH₂(CH₂) _n NH₂; n = 4, 5, 6] in the C-terminal position was synthesized based on the H-Aib-Val-Aib-Glu-Ile-Gln-Leu-Nle-His-Gln-Har-NH₂ (Har = homoarginine) template. The compounds were pharmacologically characterized at PTH1R receptors for agonist activity.     

Molecular cytogenetic studies of the “Xanthocephalum group” (Asteraceae)

Fourteen North American members of the “Xanthocephalum group” were studied by classical and molecular cytogenetics. Location and number of rDNA sites were determined by FISH. For the 5S rDNA, a probe was obtained from Prionopsis ciliata. Most species were diploid (2n?=?12), although Isocoma menziesii, Grindelia hirsutula, G. robusta, both varieties of G. stricta, and one population of G. camporum were tetraploid (2n?=?24). Diploid Grindelia and Prionopsis ciliata were 5m?+?1sm, tetraploids 10m?+?2sm, except G. hirsutula (8m?+?4sm), and Isocoma and Olivaea 6m?+?2sm and 3m?+?3sm, respectively. Most species had satellites on the short arms of m pairs: two in tetraploids and P. ciliata and one in diploids. Satellites were associated with two CMA⁺/DAPI^? bands in diploid species and four bands in tetraploids and in P. ciliata. rDNA loci (two in diploids to four in tetraploids) may be indicative of ploidy level. Grindelia tetraploids could have originated recently by autopolyploidy. Chromosome duplication was followed by modifications in the genome structure, resulting in higher heterochromatin amounts not associated with NORs. There is only one 5S site per basic genome in para or pericentromeric regions. Although not always large, chromosome variation has accompanied the evolutionary divergence of the taxa studied.     

Molecular phylogeny of the Eichhorni group of Delias Hübner, 1819 (Lepidoptera: Pieridae)

The eichhorni group lies within the genus Delias (Lepidoptera: Pieridae) which has markedly diversified aposematic wing markings. The phylogenetic relationships among all species of the eichhorni group, representatives of each of the other 21 species groups of Delias butterflies, and some related genera were analyzed based on nucleotide sequences of the mitochondrial NADH dehydrogenase subunit 5 gene. A supplemental study using the nuclear elongation factor-1alpha (EF-1alpha) gene was also carried out. The results are compared with those of morphological studies. Our results confirm the monophyly of the eichhorni group and suggest the monophyly of the genus Delias. They also indicate phylogenetic intragroup relationships, particularly the division of the eichhorni complex into groups I and II. Moreover, they also indicate that the initial diversification of the eichhorni group involved separation of the D. catisa + D. toxopei clade, followed by the divergence of other species including the eichhorni complex. Based on these findings, it is supposed that this group first appeared close to or within the western mountain range of New Guinea Island (135 degrees 30(')-140 degrees E) where D. catisa, D. toxopei, and representatives of other species cohabit.     

Begomoviruses: what is the secret(s) of their success?

Begomoviruses constitute an extremely successful group of emerging plant viruses transmitted by whiteflies of the Bemisia tabaci complex. Hosts include important vegetable, root, and fiber crops grown in the tropics and subtropics. Factors contributing to the ever-increasing diversity and success of begomoviruses include their predisposition to recombine their genomes, interaction with DNA satellites recruited throughout their evolution, presence of wild plants as a virus reservoir and a source of speciation, and extreme polyphagia and continuous movement of the insect vectors to temperate regions. These features as well as some controversial issues (replication in the insect vector, putative seed transmission, transmission by insects other than B. tabaci, and expansion of the host range to monocotyledonous plants) will be analyzed in this review.     

Description of the larva of Kempnyia colossica (Navás) (Plecoptera: Perlidae) with biological notes

In this paper, the larva of Kempnyia colossica (Navás 1934) is described based on material collected in Parque Estadual Intervales, São Paulo State, and biological notes are presented.     

Description of the male drumming signals of Besdolus bicolor (Navás 1909) (Plecoptera: Perlodidae)

The call of the male of Besdolus bicolor, produced by percussion or drumming, is described for the first time. It represents the first recorded and analyzed signal for the genus Besdolus. It consists of a repetition of two or three beat groups, with each group composed by two (rarely three) beats, and with very constant interbeat intervals and intergroup intervals (mean 0.037 seconds and 0.213 seconds, respectively). The call pattern exhibited by this species can be catalogued as an ancestral percussive signal.     

Folsomia of China I – fimetaria group (Collembola: Isotomidae)

An annotated list of the species of Folsomia fimetaria group recorded in China is given. The new diagnostics of Folsomia candida sensu lato and sensu stricto are proposed basing on European and Asiatic material. Folsomia postsensilis n. sp. is described from Ningxia and Qinghai Provinces. It is characterized by the combination of posterior position of medial sensilla on abdomen, presence of ocelli and short furca.     

New grylloblattid insects (Insecta: Grylloblattida) from the Grès à Voltzia of the Vosges (Middle Triassic of France)

New grylloblattid insects (Grylloblattida) are described from the Grès à Voltzia of the Vosges (Anisian of Alsace and Lorraine, France): Chauliodites anisicus, sp. nov. (Chaulioditidae), Palaeomesorthopteron pullus gen. et sp. nov. (Mesorthopteridae), Megakhosarodes vosgesicus sp. nov. (Megakhosaridae), Dorniella elcanoides sp. nov., D. apectinata sp. nov., D. diluta sp. nov., D. ovalis sp. nov., Baharellinus umbrosus sp. nov. Embigryllus shcherbakovi gen. et sp. nov., and Vosgesopterum arzvillerensis gen. et sp. nov. (Blattogryllidae).