Quality indexes to assess the reliability of genotypes in studies using noninvasive sampling and multiple‐tube approach

In noninvasive studies, the intersample variance in DNA quality and quantity is large, and produces multilocus genotypes of highly variable quality. Here we propose a standardized method for testing the reliability of the genotyping procedure when using the multiple‐tube approach. The quality indexes generated will allow reliable comparisons among samples, loci, studies, and field and/or laboratory protocols. These indexes represent a powerful tool for the quality management of noninvasive studies.     

Multilocus Genotyping of Pneumocystis jirovecii in Patients Developing Diverse Forms of Parasitism: Implication for a Wide Human Reservoir for the Fungus

ABSTRACT. Pneumocystis jirovecii ITS and DHPS genotypes were identified in 3 patient groups developing diverse forms of P. jirovecii infections: 13 patients with Pneumocystis pneumonia, 8 patients merely colonized by the fungus, and 19 immunocompetent infants with bronchiolitis developing mild P. jirovecii infection. Common P. jirovecii genotypes were found in the 3 patient groups, suggesting that common sources of P. jirovecii were involved in the fungus acquisition, and that transmission cycles of P. jirovecii infections in these patient groups are not independent. Parasitized patients, whatever the form of parasitism they present, may he part of a common reservoir for P. jirovecii.     

Male–female associations and female olfactory neurogenesis with pair bonding in Mus spicilegus

Mound‐building mice Mus spicilegus exhibit life‐history traits that are unique among the Mus species complex, such as the cooperative mound‐building behaviour that gives the species its common name. In this and other socially coordinated activities, such as those associated with reproduction, these mice should be able to recognize individuals (via discrimination based on kinship, population and species) to mediate their interactions. Our previous studies have provided evidence of population and species recognition in M. spicilegus. The aims of the present study were: (i) to study associations of mice during their reproductive period (in outdoor enclosures), (ii) to investigate whether there is an influence of relatedness of females in these associations, (iii) to determine whether female M. spicilegus are able to make kin vs. non‐kin discriminations, and (iv) to study certain neurobiological correlates of male–female bonds. Stable male–female associations were found in almost all the experimental groups, both those with unrelated and unfamiliar females and those with unfamiliar sisters. Kinship between females did not affect female associations in our enclosure experiment, but in our kin discrimination experiment females did distinguish between unfamiliar sisters and unfamiliar unrelated females. Shared kinship may not encourage cooperative rearing of pups but could enhance cooperation in building mounds where mice over‐winter. Male–female associations could be based on a social bond, as hypothesized from previous laboratory experiments. This was substantiated in this study by increased olfactory bulbar neurogenesis in females that preferred (in two choice tests) their sexual partner 3 weeks after their first mating. Based on these results there is clear evidence to suggest that the mating system of M. spicilegus is social monogamy. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84 , 323–334.     

Grass Leaf Elongation Rate as a Function of Developmental Stage and Temperature: Morphological Analysis and Modelling

Elongation of successive leaves was measured following defoliationof tall fescue plants in controlled environments. Measurementswere made under constant temperatures of 24 °C and 14 °C,and after temperature changes from 24 to 14 °C andvice versa.A morphological analysis of the growing leaf was made from thetime it was 1 mm long until it was fully elongated. The timeelapsed from initiation until the leaf was 1 mm long was estimated.Young leaves less than 1.5 mm long elongated slowly at a constantleaf elongation rate (LER). By extrapolating this LER back toleaf initiation from the apex it was calculated that elongationlasted 42.5 d at 24 °C and 51 d at 14 °C. Lengths ofthe division zone (DZ) and the extension-only zone (E-OZ) increasedto a maximum and then decreased during leaf development. Temperaturechange had an immediate effect on LER but the response varieddepending on the direction of the temperature change. To describethese different features, an empirical model of DZ and E-OZwas designed. Its five parameters were optimized at constanttemperature. The model was then used to simulate the LER ofplants subjected to temperature changes. Instant and lastingeffects of the initial temperature on mean LER in plants transferredfrom 14 to 24 °C andvice versawere well simulated. It wasconcluded that the major reason for differences was due to thegrowth stage (DZ and E-OZ lengths) at which the changes occurredat both temperatures.Copyright 1999 Annals of Botany Company Festuca arundinaceaSchreb., tall fescue, growth zone, division zone.     

A Nitrogen-led Model of Grass Growth

This model is built by considering the utilization rate of nitrogenas the first step in calculating the rate of growth of the variousorgans of a grass crop. The amount of carbohydrate determineswhether there are sufficient carbon skeletons and sufficientenergy available to support synthesis of new material. Growthof roots, tillers/stems and leaves is simulated with leaf dividedinto photosynthetic and non-photosynthetic structures. The modelkeeps account of soluble carbohydrate and nitrogen pools ineach of the organs and storage pools of carbohydrate in theleaves and roots. The modelled crop has an age structure sothat each plant organ has an age profile describing daily changesin growth; when the oldest tissue becomes senescent a fractionof its nitrogen is recycled. Seasonal changes in the percentage nitrogen content of the crop,when large amounts of soil nitrogen are available, are shownto be a consequence of changes in both soluble and stored carbohydrate.The contrast between high and low nitrogen treatments is shownto be a consequence of different allocation priorities for nitrogen. The model demonstrates that considering nitrogen as the primaryelement of synthesis provides an approach that predicts drymatter production successfully, as well as giving a differentperspective of the growth processes, and suggesting that thecapacity of the enzymatic processes governing synthesis ultimatelylimits crop yields. This different perspective may be most usefulwhen trying to understand what controls growth and the relativeinfluence of environmental changes on the physiology and morphologyof the crop. C:N ratio; grass growth; mathematical model; nitrogen use; partitioning