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.     

Whole Grain Intakes in the Diets Of Malaysian Children and Adolescents – Findings from the MyBreakfast Study

Background

Diets rich in whole grain are associated with several health benefits. Little is known however, about whole grain consumption patterns in Malaysia. The aim of this study was to assess whole grain intakes and dietary source in Malaysian children and adolescents.

Methods

This analysis is from the MyBreakfast study, a national cross sectional study investigating eating habits among primary and secondary school children throughout Malaysia, conducted in 2013. Children (n = 5,165) and adolescents (n = 2,947) who completed two days of dietary assessment using a food record or recall respectively were included. The whole grain content of foods was estimated mainly through the use of quantitative ingredient declarations on food labels. All wholegrain foods were considered irrespective of the amount of whole grain they contained.

Results

Overall, only 25% of children and 19% of adolescents were wholegrain consumers. Mean daily intakes in the total sample were 2.3g/d (SD 5.8g/d) in children and 1.7g/d (SD 4.7g/d) in adolescents and in the consumer’s only sample, mean intakes reached 9.1g/d (SD 8.6) and 9.2g/d (SD 7.1g/d) respectively. Wheat was the main grain source of whole grain while ready to eat breakfast cereals and hot cereals were the main food contributors. Less than 3% of the children and adolescents reached the US quantitative whole grain recommendation of 48g/day.

Conclusion

Whole grain is consumed by only a minority of Malaysian children and adolescents and even among consumers, intakes are well below recommendations. Efforts are needed to firstly understand the barriers to whole grain consumption among Malaysian children in order to design effective health promotion initiatives to promote an increase in whole grain consumption.     

Cigarette smoke-induced accumulation of lung dendritic cells is interleukin-1α-dependent in mice

Background

Evidence suggests that dendritic cells accumulate in the lungs of COPD patients and correlate with disease severity. We investigated the importance of IL-1R1 and its ligands IL-1α and β to dendritic cell accumulation and maturation in response to cigarette smoke exposure.

Methods

Mice were exposed to cigarette smoke using a whole body smoke exposure system. IL-1R1-, TLR4-, and IL-1α-deficient mice, as well as anti-IL-1α and anti-IL-1β blocking antibodies were used to study the importance of IL-1R1 and TLR4 to dendritic cell accumulation and activation.

Results

Acute and chronic cigarette smoke exposure led to increased frequency of lung dendritic cells. Accumulation and activation of dendritic cells was IL-1R1/IL-1α dependent, but TLR4- and IL-1β-independent. Corroborating the cellular data, expression of CCL20, a potent dendritic cells chemoattractant, was IL-1R1/IL-1α-dependent. Studies using IL-1R1 bone marrow-chimeric mice revealed the importance of IL-1R1 signaling on lung structural cells for CCL20 expression. Consistent with the importance of dendritic cells in T cell activation, we observed decreased CD4⁺ and CD8⁺ T cell activation in cigarette smoke-exposed IL-1R1-deficient mice.

Conclusion

Our findings convey the importance of IL-1R1/IL-1α to the recruitment and activation of dendritic cells in response to cigarette smoke exposure.     

Cd uptake by intact wheat plants

Abstract. An investigation of the uptake of Cd by intact wheat plants has been carried out. The accumulation of Cd in the roots as a function of time and external Cd concentration was determined. Since the transport of Cd to the grains and shoots was found to be small, only uptake into the root was examined further. An appreciable fraction of the Cd absorbed by the roots can be desorbed and consequently constitutes the freely diffusible and exchangeable fraction.
The effect of temperature and of metabolic inhibitors on the absorption provides evidence that another Cd fraction is taken up by metabolically mediated processes. The absorption of this Cd fraction was found to be inhibited by Cu and Zn. The inhibitory effect of Cu and Zn on Cd absorption was comparable.     

Monoclonal Antibodies Identify a Subset of Dense Granules in Cryptosporidium parvum Zoites and Gamonts

ABSTRACT. Two monoclonal antibodies raised against purified oocysts and excysted sporozoites of Cryptosporidium parvum identified antigens located in the anterior half of sporozoites by indirect immunofluorescence microscopic assay. The monoclonal antibodies also reacted with Triton X-100-insoluble antigens of asexual and sexual stage parasites developing in epithelial cells in vitro and identified a 110 kilodalton antigen on immunoblots of sodium dodecyl sulfate-extracted oocysts. Immunoblotting reactivity was abolished by prior treatment of blotted antigen with periodic acid suggesting that the monoclonal antibodies recognize a carbohydrate or carbohydrate-dependent epitope(s). By immunoelectron microscopy, the antibodies reacted with a family of small, electron-dense granules located predominantly in the central region of merozoites and also with a population of cytoplasmic inclusions in macrogamonts. In addition, the monoclonal antibodies prominently labeled the parasitophorous vacuole membrane of all intracellular stages examined suggesting that the corresponding antigen(s) may be exocytosed from the granules to become associated with Triton X-100-insoluble components of the vacuolar membrane or cytoskeleton.     

Three-Dimensional Reconstruction of Rabbit-Derived Pneumocystis carinii from Serial-Thin Sections I: Trophozoite

The highly complex ultrastructural morphology of the endomembrane system in Pneumocystis carinii led us to perform three-dimensional reconstruction from serial-thin sections using the CATIA (Conception Assistée Tridimensionnelle Inter Active) Dassault system program. The three-dimensional reconstruction of a small trophozoite made it possible to better understand the morphological relationship among organelles and to suggest cytophysiological hypotheses. By reconstructing other parasite stages, we gathered information about the evolution of organelles during the life cycle and about their physiology.     

Chromosomal introgression in house mice from the hybrid zone between M. m. domesticus and M. m. musculus in Denmark

The recent discovery of Robertsonian (Rb) translocations in Danish mice from the hybrid zone between Mus musculus musculus and M. m. domesticus stimulated the chromosomal analysis of populations along a north-south transect through this zone. G-Banding identified the Rb fusions as Rb(3.8), Rb(2.5) and Rb(6.9). The cytogenetic results show that there is a gradual decrease in the number of fusions as one proceeds north, the translocations abruptly ending in populations from the centre of the hybrid zone determined by seven diagnostic allozymic markers. These results indicate that Rb fusions are present only in domesticus or predominantly domesticus-genotype mice and that they do not introgress into M. m. musculus . To test if genie incompatibilities between the musculus genetic background and Rb fusions were involved in the systematic elimination of the latter, predominantly musculus mice from the hybrid zone were crossed with Rb domesticus mice carrying Rb(3.8). The karyotypic analysis of the progeny showed no distortion of the transmission ratio of this fusion.
The chromosomal and allozymic analysis of these mice further indicates that (i) recombination is not suppressed between metacentrics and their acrocentric homologues and (ii) specific domesticus chromosomal segments are tolerated in the musculus genomes whereas the Rb centromeres are not.