Oxypetalum banksii subsp. banksii: a taxon of Asclepiadaceae with an extragynoecial compitum

 The floral morphology of seven Oxypetalum species and, in particular, the spatial relationship between the five stigmatic chambers and two separate ovaries of their flowers with respect to transmission of the pollen tube are studied. In all species, except O. banksii subsp. banksii, floral morphology is similar to that in other Asclepiadeae, and the flowers pollinated with one pollinium develop only one follicle, which means compitum absence. In O. banksii subsp. banksii flowers, the secretory interstaminal tissue lines the inner walls of the stigmatic chambers as in the other species studied, but it also reaches the upper part of the inner surface of the filament tube, where it surrounds the styles, an unprecedented feature for Asclepiadaceae. This tissue secretes nectar and mucilage; the latter acts as transmitting medium for the growth of pollen tubes from pollinia inserted and hydrated in stigmatic chambers (“hyperstigmas”). Mucilage also functions as an extragynoecial compitum: in flowers pollinated with one pollinium both carpels develop into a follicle. Received August 28, 2001; accepted April 9, 2002 Published online: October 14, 2002 Addresses of the authors: Milene Faria Vieira (e-mail: mfvieira@mail.ufv.br), Departamento de Biologia Vegetal, Universidade Federal de Vi?osa, 36571-000, Vi?osa, Minas Gerais, Brazil. George John Shepherd, Departamento de Botanica, Instituto de Biologia, Universidade Estadual de Campinas, C.P. 6109, 13083-970, Campinas, S?o Paulo, Brazil.     

Computational Oral Absorption Simulation for Low‐Solubility Compounds

Bile micelles play an important role in oral absorption of low‐solubility compounds. Bile micelles can affect solubility, dissolution rate, and permeability. For the pH–solubility profile in bile micelles, the Henderson–Hasselbalch equation should be modified to take bile‐micelle partition into account. For the dissolution rate, in the Nernst–Brunner equation, the effective diffusion coefficient in bile‐micelle media should be used instead of the monomer diffusion coefficient. The diffusion coefficient of bile micelles is 8‐ to 18‐fold smaller than that of monomer molecules. For permeability, the effective diffusion coefficient in the unstirred water layer adjacent to the epithelial membrane, and the free fraction at the epithelial membrane surface should be taken into account. The importance of these aspects is demonstrated here using several in vivo and clinical oral‐absorption data of low‐solubility model compounds. Using the theoretical equations, the food effect on oral absorption is further discussed.     

In vitro propagation of the medicinal plant Plumbago zeylanica L. Through nodal explants

Summary A protocol for rapid in vitro propagation using nodal explants obtained from 2-yr-old, field-grown medicinal plants of Plumbago zeylanica L. belonging to the family Plumbaginaceae is described. High frequency bud break and fast development of shoots were induced on Murashige and Skoog's basal medium supplemented with 27.2 μM adenine sulfate +2.46 μM indole-3-butyric acid (IBA). Induction of rooting was achieved by transferring the shoots to the same basal medium containing 4.92 μM IBA. Using our protocol from one twig of P. zeylanica (eight responsive nodes per explant shoot) within a period of 5 mo., eight plantlets could be raised. After a hardening period of 4 wk, there was a 90% transplantation success in the field compared to the 60–65% survival of plantlets recorded in the experiments of previous workers. The plantlets derived through in vitro propagation mimic the growth and morphological characteristics of the donor plants.     

Mosquito larvicidal activity of Aloe vera (Family: Liliaceae) leaf extract and Bacillus sphaericus,against Chikungunya vector,Aedes aegypti

The bio-efficacy of Aloe vera leaf extract and bacterial insecticide, Bacillus sphaericus larvicidal activity was assessed against the first to fourth instars larvae of Aedes aegypti, under the laboratory conditions. The plant material was shade dried at room temperature and powdered coarsely. A. vera and B. sphaericus show varied degrees of larvicidal activity against various instars larvae of A. aegypti. The LC₅₀ of A. vera against the first to fourth instars larvae were 162.74, 201.43, 253.30 and 300.05 ppm and the LC₉₀ 442.98, 518.86, 563.18 and 612.96 ppm, respectively. B. sphaericus against the first to fourth instars larvae the LC₅₀ values were 68.21, 79.13, 93.48, and 107.05 ppm and the LC₉₀ values 149.15, 164.67, 183.84, and 201.09 ppm, respectively. However, the combined treatment of A. vera + B. sphaericus (1:2) material shows highest larvicidal activity of the LC₅₀ values 54.80, 63.11, 74.66 and 95.10 ppm; The LC₉₀ values of 145.29, 160.14, 179.74 and 209.98 ppm, against A. aegypti in all the tested concentrations than the individuals and clearly established that there is a substantial amount of synergist act. The present investigation clearly exhibits that both A. vera and B. sphaericus materials could serve as a potential larvicidal agent. Since, A. aegypti is a container breeder vector mosquito this user and eco-friendly and low-cost vector control strategy could be a viable solution to the existing dengue disease burden. Therefore, this study provides first report on the mosquito larvicidal activity the combined effect of A. vera leaf extract and B. sphaericus against as target species of A. aegypti.     

Fasciola hepatica: effect of 4-amino-6-trichloroethenyl-1,3-benzenedisulfonamide on glycolysis in vitro

In vitro, 4-amino-6-trichloroethenyl-1,3-benzenedisulfonamide, a potent fasciolicide, causes a potent concentration-dependent inhibition of glucose uptake by mature Fasciola hepatica. In F. hepatica treated with the disulfonamide and then fed [U-¹⁴C]glucose, there was a 60% inhibition of glucose utilization and a corresponding inhibition of acetate and propionate formation. Treated fluke parasites possessed much lower levels of adenosine triphosphate, phosphoenolpyruvate, glucose 6-phosphate, and fructose 6-phosphate than untreated parasites and contained higher levels of glycerol and the free sugars fructose and mannose. Direct measurement of the effect of the disulfonamide on the glycolytic enzymes of F. hepatica demonstrated that 3-phosphoglycerate kinase (EC 2.7.2.3) and phosphoglyceromutase (EC 2.7.5.3) were inhibited. It is therefore suggested that the fasciolicidal activity of 4-amino-6-trichloroethenyl-1, 3-benzenedisulfonamide is due to inhibition of the enzymes 3-phosphoglycerate kinase and phosphoglyceromutase which effectively blocks the Embden-Myerhof glycolytic pathway.     

Calmodulin and the target size of the (Ca2+ + Mg2+)-ATPase of human red-cell ghosts

An average target size of 251 kDa has been obtained for the (Ca²⁺ + Mg²⁺)-ATPase of calmodulin-depleted erythrocyte ghosts by radiation inactivation with 16 MeV electrons. This is close to twice the size of the purified calcium-pump polypeptide. When calmodulin was included during the ATPase assay, a component of about 1 MDa appeared in addition to the activated dimer.     

Inhibitory effect of heavy water on mutability of chemically injured Escherichia coli cells

After E. coli cells (WP2 and WP2uvrA) were treated with chemical mutagens (methyl methanesulfonate, MMS; N-methyl-N-nitrosourea, MNU; 4-nitroquinoline 1-oxide, 4NQO) in 1/15 M phosphate buffer, the mutability of the treated cells plated on a D₂O-agar plate was compared with that plated on an ordinary H₂O-agar plate. The mutation frequency decreased more or less on the D₂O-agar plate. The D₂O-substitution effects, as termed by the relative mutation frequencies (MF_D2O/MF_H2O), are 0.92 for MMS, 0.29 for MNU, and 0.42 for 4NQO in WP2, and 0.68 for MMS, 0.49 for MNU, and 0.16 for 4NQO in WP2uvrA. The D₂O effect seemed to be partly related to the function of the uvrA gene-associated products. The pH dependence of mutability was discussed in connection with the D₂O-substitution effect.     

Recovery of methanotrophs from disturbance: population dynamics,evenness and functioning

Biodiversity is claimed to be essential for ecosystem functioning, but is threatened by anthropogenic disturbances. Prokaryotes have been assumed to be functionally redundant and virtually inextinguishable. However, recent work indicates that microbes may well be sensitive to environmental disturbance. Focusing on methane-oxidizing bacteria as model organisms, we simulated disturbance-induced mortality by mixing native with sterilized paddy soil in two ratios, 1:4 and 1:40, representing moderate and severe die-offs. Disturbed microcosms were compared with an untreated control. Recovery of activity and populations was followed over 4 months by methane uptake measurements, pmoA-qPCR, pmoA-based terminal restriction fragment length polymorphism and a pmoA-based diagnostic microarray. Diversity and evenness of methanotrophs decreased in disturbed microcosms, but functioning was not compromised. We consistently observed distinctive temporal shifts between type I and type II methanotrophs, and a rapid population growth leading to even higher cell numbers comparing disturbed microcosms with the control. Overcompensating mortality suggested that population size in the control was limited by competition with other bacteria. Overall, methanotrophs showed a remarkable ability to compensate for die-offs.