A Simple Method for Isolating DNA of High Yield and Quality from Cotton (shape Gossypium hirsutum L.) Leaves

An easy, reproducible and fast procedure to isolate DNA from cotton leaves is described. The addition of 0.5 M glucose in the extraction buffer avoids browning by polyphenolic compounds and improves the quality of DNA for molecular analysis. The DNA yield ranged between 150–400 mg per gram of fresh tissue. The DNA was suitable for digestion by restriction enzymes and amplificatiion by Taq DNA polymerase.     

Mesocyclops longisetus effects on survivorship of Aedes aegypti immature stages in car tyres

Abstract .The effect of the introduction of the entomophagous copepod Mesocyclops longisetus (Acuacultura F.C.B. strain) on the survival of Aedes aegypti immature stages in car tyres was evaluated under semi-natural conditions in the municipality of Merida, Yucatan, Mexico. Life tables were constructed for the immature stages of the mosquito in the presence and absence of M. longisetus , and the survival data were compared using log–linear models. The data set was adjusted using the GLIM statistical package and the quality of adjustment was evaluated with a chi-squared test . Survivorship curves were constructed for each treatment.
In the absence of M. longisetus , the survivorship of Ae. aegypti immature stages averaged 9%. The highest mortality rate was observed during the fourth larval instar (54%) and the resulting survival pattern corresponded to a type II survivorship curve. The mortality rate of Ae. aegypti first-instar larvae (fifty per tyre) increased more than 200-fold in the presence of M. longisetus (twenty per tyre) and the highest mortality was during the first two larval instars, where it reached 98.9%, with a resulting survivorship of 0.2%. Overall mortality was sixfold greater in the presence of the copepod than in its absence. The survival pattern of immature stages of Ae. aegypti in the presence of the copepod corresponded to a type III survivorship curve. As M. longisetus was so effective against Ae. aegypti immature stages in tyres under semi-natural conditions, its long-term effectiveness should be evaluated under socially and ecologically realistic field conditions in Mexico.     

The incidence of Weeksella- and Bergeyella-like bacteria in the food environment

Eighty-five catalase- and oxidase-positive Gram-negative rods and cocci susceptible to penicillin G were isolated from a variety of food sources. The phenotypic relationships of these isolates with reference cultures of Bergeyella -like, Chryseobacterium, Empedobacter, Myroides , Moraxella , Sphingobacterium and Weeksella -like strains were examined by numerical taxonomy. Seventy-three isolates were recovered in five groups; 80% of the isolates clustered in groups 1, 2 and 3 and produced indole, bearing a strong resemblance to Weeksella and Bergeyella . They could not, however, be regarded as belonging to the known species of W. virosa and B. zoohelcum . It is suggested that three species may be necessary to accommodate the environmental Weeksella - or Bergeyella -like bacteria. The isolates in groups 4 and 5 had white colonies and were unable to produce indole, in this way resembling the Moraxella genus.     

Biogenesis of β-Carotene in Mycobacterium kansasii

The biogenesis of beta-carotene in the photochromogen Mycobacterium kansasii consists of two reactions. The first reaction is photochemical, and is dependent on the wavelength of the incident light and on oxygen but is independent of temperature. The second reaction does not require illumination, and is dependent on the temperature and on oxygen. The latter, or dark reaction, requires the synthesis of new protein, and was shown to have the characteristics of an inducible system. Carotenogenesis was stimulated by incident light of wavelengths of 420, 540, and 650 nm. Immediately after illumination there was an increase in the synthesis of ribonucleic acid and beta-carotene accumulation started after a lag of 8 to 10 min. The synthesis of beta-carotene exhibited temperature dependence with an optimum of about 36 C.     

On the derivation of a mean growth equation for cell cultures

IfN(t) is the expected number of cells in a culture at timet, the corresponding time derivative, andf(t−τ)dt the probability that a cell of aget−τ at timet will divide in the succeeding time intervaldt, then according to Hirsch and Engelberg (this issue) there obtains the integral equation for describing the dynamics of the cell population. It is the purpose of this note to give two alternative derivations of this equation, one based on the age density equation of Von Foerster, and the other based on a generalized form of the Harris-Bellman equation describing the first moment of an age dependent, branching process. In addition, a probability model is posed from which the Von Foerster equation and, hence, the Hirsch-Engelberg equation readily follows.     

Release of iron from ferritin by semiquinone, anthracycline, bipyridyl, and nitroaromatic radicals

The cytotoxicity of many xenobiotics is related to their ability to undergo redox reactions and iron dependent free radical reactions. We have measured the ability of a number of redox active compounds to release iron from the cellular iron storage protein, ferritin. Compounds were reduced to their corresponding radicals with xanthine oxidase/hypoxanthine under N₂ and the release of Fe²⁺ was monitored by complexation with ferrozine. Ferritin iron was released by a number of bipyridyl radicals including those derived from diquat and paraquat, the anthracycline radicals of adriamycin, daunorubicin and epirubicin, the semiquinones of anthraquinone-2-sulphonate, 1,5 and 2,6-dihydroxyanthraquinone, 1-hydroxyanthraquinone, purpurin, and plumbagin, and the nitroaromatic radicals of nitrofurantoin and metronidazole. In each case, iron release was more efficient than with an equivalent flux of superoxide. Introduction of air decreased the rate of iron release, presumably because the organic radicals reacted with O₂ to form superoxide. In air, iron release was inhibited by superoxide dismutase. Semiquinones of menadione, benzoquinone, duroquinone, anthraquinone 1,5 and 2,6-disulphonate, 1,4 naphthoquinone-2-sulphonate and naphthoquinone, when formed under N₂, were unable to release ferrin iron. In air, these systems gave low rates of superoxide dismutase-inhibitible iron release. Of the compounds investigated, those with a single electron reduction potential less than that of ferritin were able to release ferritin iron.     

The Problematic Paralbunea Hu and Tao, 1996: Homonymy, Generic Nom. Nov., and Correct Taxonomic Placement

The fossil genus Paralbunea Hu and Tao, described as an anomuran albuneid, is a junior homonym of Paralbunea Serène and a possible synonym of either the brachyuran raninid Ranilia H. Milne Edwards, 1837, or Cosmonotus Adams and White, 1848. The type series of P. taipeiensis Hu and Tao is composed of at least two species belonging to two raninid genera and appears (in part) assignable to the genus Ranilia and (in part) to Cosmonotus grayi Adams and White, 1848. However, due to both limited availability and poor quality of the holotype of Paralbunea taipeiensis , and destruction of the paratypes, this taxon cannot be unequivocally synonymized with any particular raninid taxon and a new name is proposed to replace Hu and Tao's preoccupied generic name. Caution is urged when describing purported albuneid fossils, due to strong convergence with raninid crabs, which are far more common in the fossil record.