Simplex optimization of the variables affecting the micelle-stabilized room temperature phosphorescence of 6-methoxy-2-naphthylacetic acid and its kinetic determination in human urine

This article reports the kinetic determination of 6-methoxy-2-naphthylacetic acid (6-MNA), the major metabolite of nabumetone, from micelle-stabilized room temperature phosphorescence (MS-RTP) measurements made by using the stopped-flow mixing technique. This methodology allows one to determine analytes in complex matrices without the need for a tedious separation process. It also shortens analysis times substantially. The proposed method uses simplex methodology to optimize the chemical and instrumental variables affecting the phosphorescence. It was applied to the determination of 6-MNA in human urine. The maximum phosphorescence signal is obtained within only 10 s after the sample is prepared. The maximum slope of the kinetic curve, which corresponds to the maximum rate of the phosphorescence development, is measured at lambda(ex)=273 nm and lambda(em)=516 nm. Least-squares regression was used to fit experimental data, and the detection limit, repeatability, and standard deviation for replicate samples were determined.     

Precise excision of the large pathogenicity island, SPI7, in Salmonella enterica serovar Typhi

The large pathogenicity island (SPI7) of Salmonella enterica serovar Typhi is a 133,477-bp segment of DNA flanked by two 52-bp direct repeats overlapping the pheU (phenylalanyl-tRNA) gene, contains 151 potential open reading frames, and includes the viaB operon involved in the synthesis of Vi antigen. Some clinical isolates of S. enterica serovar Typhi are missing the entire SPI7, due to its precise excision; these strains have lost the ability to produce Vi antigen, are resistant to phage Vi-II, and invade a human epithelial cell line more rapidly. Excision of SPI7 occurs spontaneously in a clinical isolate of S. enterica serovar Typhi when it is grown in the laboratory, leaves an intact copy of the pheU gene at its novel join point, and results in the same three phenotypic consequences. SPI7 is an unstable genetic element, probably an intermediate in the pathway of lateral transfer of such pathogenicity islands among enteric gram-negative bacteria.     

Agrobacterium rhizogenes transformation of the Phaseolus spp.: a tool for functional genomics

A fast, reproducible, and efficient transformation procedure employing Agrobacterium rhizogenes was developed for Phaseolus vulgaris L. wild accessions, landraces, and cultivars and for three other species belonging to the genus Phaseolus: P. coccineus, P. lunatus, and P. acutifolius. Induced hairy roots are robust and grow quickly. The transformation frequency is between 75 and 90% based on the 35-S promoter-driven green fluorescent protein and beta-glucuronidase expression reporter constructs. When inoculated with Rhizobium tropici, transgenic roots induce normal determinate nodules that fix nitrogen as efficiently as inoculated standard roots. The A. rhizogenes-induced hairy root transformation in the genus Phaseolus sets the foundation for functional genomics programs focused on root physiology, root metabolism, and root-microbe interactions.     

K+ channels involved in contractility of rabbit small intestine

Most excitable cells, including gastrointestinal smooth muscle cells, express several types of K+ channels. The aim of this study was to examine the types of K' channels involved in the contractility of longitudinal smooth muscle of rabbit small intestine in vitro. Spontaneous contractions and KCl-stimulated contractions were reduced by atropine, phentolamine, propranolol, suramin, tetrodotoxin and indomethacin. The amplitude and tone of spontaneous contractions were increased by apamin, charybdotoxin, iberiotoxin, E4031, tetraetylammonium (TEA) and BaCl2. The frequency of contractions was reduced in the presence of apamin and TEA and increased by charybdotoxin. It was found that 4-aminopyridine increased the tone of spontaneous contractions and reduced the amplitude and frequency of contractions. Glibenclamide did not modify the amplitude, frequency or tone of contractions. KCl-stimulated contractions were increased by E4031, were not modified by apamin, glibenclamide, NS1619 or diazoxide, and were reduced by charybdotoxin, TEA, 4-aminopyridine or BaCl2. These results suggest that both Ca2+-activated K+ channels of small and high conductance, and HERG K+ channels and inward rectifier K+ channels participate in spontaneous contractions of small intestine. On the other hand, voltage-dependent K+ channels, HERG K+ channels, inward rectifier K+ channels and high conductance Ca2+-activated K+ channels are involved in KCl-stimulated contractions.     

Interactions between an ectoparasitoid and a nucleopolyhedrovirus when simultaneously attacking Spodoptera exigua (Lepidoptera: Noctuidae)

Insect pathogenic viruses and parasitoids represent distinct biological entities that exploit a shared host resource and have similar effects in suppressing host populations. This study explores the interactions between the ectoparasitoid Euplectrus plathypenae (Hymenoptera: Eulophidae) and the Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) in larvae of S. exigua (Lepidoptera: Noctuidae). Parasitoid progeny failed to complete development in hosts that had been infected prior to parasitism. However, infection of S. exigua fourth instars at 48 h post‐parasitism had no significant effects on the survival of parasitoid progeny. Larval and pupal development times of E. plathypenae that survived on virus‐infected S. exigua did not differ significantly from that of parasitoids on healthy hosts. Virus‐induced mortality and the production of occlusion bodies were very similar in parasitized and non‐parasitized S. exigua. The virus was genetically stable over three passages in parasitized and unparasitized hosts. These results suggest that applications of SeMNPV‐based insecticides are unlikely to disrupt pest control exerted by the parasitoid E. plathypenae in biological pest control programs as long as virus applications are timed not to coincide with parasitoid releases.     

Fecundity and life table parameters of Campoletis sonorensis (Hymenoptera: Ichneumonidae), an endoparasitoid of the Cabbage Looper Trichoplusia ni Hübner (Lepidoptera: Noctuidae), under laboratory conditions

The fecundity and life table parameters of Campoletis sonorensis females were measured using thirty 4-day-old Trichoplusia ni larvae daily at 24°C, 60% RH and a photoperiod of 12 h L:12 h D. The mean longevity was 34.5±2.8 days, the mean oviposition period was 22.7±1.9 days, and the mean constant oviposition period and the mean post-oviposition period were 15.9±1.3 and 11.9±2.2 days, respectively. The mean realised fecundity and the mean fertility differed significantly at 66.9±7.8 and 60.4±7.8 parasitoids per female, respectively. The mean sex ratio for the mean oviposition period (23 days) was 0.13±0.07, indicating a highly female biased ratio. The life table parameters were: intrinsic rate of natural increase (r _m), 0.135 female/day; gross reproductive rate (GRR), 50.30; net reproductive rate (R _o), 49.96; finite capacity for increase (λ), 1.14 female/day; mean generation time (T), 28.97 days; doubling time (DT), 5.13; capacity for increase (r _c), 0.33; and cohort generation time (T _c), 11.69. Campoletis sonorensis may be a suitable candidate for a biocontrol program of T. ni populations mostly because the primary selection criterion, r_m , obtained for this parasitoid can be similar to or larger than the rate obtained for T. ni.     

Morphological evidence of hybridization between Ramphocelus flammigerus subspecies (Passeriformes: Thraupidae) in Colombia

Habitat modifications such as deforestation and the increase of agricultural activities, have led to uncommon faunal interactions. In Colombia, this condition have caused the secondary contact of subspecies of Ramphocelus flammigerus populations from Cauca valley and the Pacific coast; and some specimens with rumps of intermediate colors of the subspecies have been found and are thought as hybrids. The objective of this study was to assess the presence of morphological evidence that may suggest hybridization and may explain the origin of individuals with intermediate coloration. We predict that if subspecies hybridize, they will be more similar in morphology when coexisting than when separated. Alternatively, coexisting subspecies might diverge in sympatry, because of selection to reduce competition for resources (character displacement). For this, a survey in 15 localities was undertaken: 10 allopatric areas (five for each subspecies), and five sympatric areas. Mist nets were used to capture individuals and a total of seven morphological characters were measured. To identify the patterns of morphological variation, we compared morphology of subspecies, sympatric and allopatric populations and individuals of intermediate colors. Consequently, we performed discriminant analysis and test for differences between groups by using 95% confidence intervals for log-ratio tests. A total of 112 individuals were captured (46 intermediate-colored individuals, 20 R. f. flammigerus, and 46 R.f. icteronotus. Discriminant analyses showed that subspecies were well differentiated, and intermediate individuals overlapped with them. Log-ratio test, based on Mahalanobis distances, showed that intermediate individuals were morphologically more similar to both subspecies than subspecies themselves. In addition, log-ratio tests showed that subspecies sympatric populations were similar but allopatric ones were different, and that individuals of intermediate colors were more similar to sympatric than to allopatric populations of the two subspecies. Therefore, morphological evidence supports the predictions of a hybridization hypothesis among the subspecies of R. flammigerus. In conclusion, the analysis of morphological variation in R. flammigerus suggests that hybridization between subspecies is occurring and that a process of genetic introgression is probably in progress.