In vitro responses in Passiflora species with different chromosome numbers,ploidy levels and nuclear 2C values: revisiting and providing new insights

Plant Cell, Tissue and Organ Culture (PCTOC) - Tissue culture in Passiflora has emerged as a strategy to propagate species with agronomic relevance, which is the main focus of most in vitro...     

On the Estimation of the Size of a Finite and Closed Population

In this paper, we consider the problem of estimating the size N of a finite and closed population, using data obtained from capture-recapture experiments. By defining an appropriate model, we investigate the maximum of the likelihood, of the profile likelihood and of an orthogonal adjusted profile likelihood (COX and REID, 1987) function. We show that they all may present infinity as the maximum likelihood estimator of N. This seems to be a characteristic of the likelihood approach in this problem. Further, we present a Bayesian approach with minimum prior information as a way of countering this difficulty. Exact analytical expressions for the posterior modes are also obtained.     

Time-concentration interplay in insecticide resistance among populations of the Neotropical coffee leaf miner,Leucoptera coffeella

1. Leucoptera coffeella is one of the main coffee pests in the Neotropical region and particularly important in crops cultivated under full sun, as in Brazil. The intensive use of insecticides in the last two decades, including molecules of recent use such as chlorantranilprole, has not been successful in suppressing this pest species.
2. Thus, study aimed to detect insecticide resistance and determine the levels of resistance to commercial formulations of the insecticides chlorantraniliprole, chlorpyrifos and thiamethoxam in populations of L. coffeella from Arabica coffee fields in western and the highlands of the state Bahia (Brazil). Furthermore, as the expression of insecticide toxicity varies with the length of exposure and the compound concentration, what is frequently neglected, these two variables were considered while determining the levels of resistance in nine populations.
3. Moderate levels of resistance were detected to chlorantranilprole in two populations, whereas the others exhibited low levels of resistance. All populations were resistant to thiamethoxam ranging from low to moderate levels. Low levels of resistance to chlorpyrifos were detected in all populations from western, but none from highlands region.
4. The western presents a more concerning scenario of insecticide resistance the L. coffeella, but the phenomenon requires attention in both regions.

     

Phylogeny and biogeography of tetralophodont rodents of the tribe Oryzomyini (Cricetidae: Sigmodontinae)

Oryzomyini is the richest tribe among the Sigmodontine rodents, encompassing 32 living and extinct genera and including an increasing number of recently described species and genera. Some Oryzomyini are tetralophodont showing a reduction in the number of molar folds to four, while most taxa in this tribe retain the plesiomorphic pentalophodont state. We applied phylogenetic methods, molecular dating techniques and ancestral area analyses to members of an oryzomyini clade informally named ‘D’ in former studies and included related fossil tetralophodont forms. Based on 98 morphological characters and sequences of five gene fragments, we found that the tetralophodont condition is paraphyletic. Among living taxa, Pseudoryzomys is sister to Holochilus, and Lundomys is derived from a basal divergence. A clade formed by living Holochilus and the fossils Noronhomys and Carletonomys is sister to Holochilus primigenus, making Holochilus paraphyletic. Therefore, we describe a new genus that accommodates the fossil H. primigenus. Because trans‐Andean taxa currently share a common ancestor with taxa of cis‐Adean distribution, the northern Andes uplift may have worked as a postdispersal barrier. The tetralophodont lineages diverged during the Pliocene from a cis‐Andean ancestor, and the Great Plains in South America may have favoured the diversification of tetralophodont forms adapted to open habitats during the Pliocene.     

Disposition of trace elements in the mangrove ecosystem and their effects on Ucides cordatus (Linnaeus, 1763) (Crustacea,Decapoda)

BioMetals - The tropical mangrove at the Estação Ecológica do Lameirão (Southeastern Brazil), an ecosystem of high socio-economic value, receives a large load of pollutants from...     

Infection of the athymic rat by Toxoplasma gondii

In contrast to normal rats which are resistant to T. gondii infection (10(7) tachyzo?tes), athymic rats did not survive an intraperitoneal infection with 10(3) toxoplasma. When nude rats were injected intravenously with lymph node cells from hirsute littermates, they became resistant in a dose-dependent manner to the infection. In addition, reconstituted athymic rats having survived for more than 4 months the first infection were also protected against a second challenge with 10(5) tachyzo?tes. Anti-T. gondii antibody levels detected in reconstituted athymic rats were related to protection. These preliminary findings suggest that T-dependent immunity is essential in the development of effector mechanisms involving antibodies in resistance to toxoplasmosis.     

Effect of excess water in an oxisol on ammonium,nitrate, iron and manganese availability and nutrient uptake of two tropical forage species

Summary A glasshouse experiment was conducted to determine how reduction conditions would affect plant nutrient availability and uptake in a red-yellow latosol (Acrustox). Soil analysis showed that the most important changes were a marked increase in extractable iron and an inhibition of nitrification. The grass andropogon (Andropogon gayanus Kunth var.bisquamulatus (Hoechst) Hack) and the legume stylo (Stylosanthes capitata (Vog)) responded differently to reducing conditions.Andropogon showed low P, Ca, Mg, Fe and Mn content in the shoots but an intense coating of oxidized iron was observed on the surface of roots. Stylo plants, on the other hand, showed no iron deposition on the root surfaces but a high iron content in the shoots. No decreased P, Ca or Mg content was observed in this case. It was concluded that in water saturated soil, reduction took place and plant performance was affected not only by restricted root development but by preventing P, Ca and Mg uptake in andropogon and increasing Fe uptake in stylo plants. It is suggested that restricted P, Ca and Mg uptake by andropogen would be the result of iron deposition on root surfaces.