Molecular Orbital Study of Hapten–Antibody Interactions

THERE is considerable interest in the application of quantum chemical calculations to pharmacology¹. Quantum mechanical methods can be used to compute submolecular properties, such as charge distribution in a molecule. For a series of compounds eliciting the same type of response a correlation is sought between activity and some function of computed parameters.     

The karyology of some Taraxacum species from alpine regions of Europe

The karyotypes of 18 samples assigned to 13 agamospecies in Taraxacum are described. The species are classified among six sections; Eiythrosperma Lindb. f., Vulgaria Dahlst., Alpestria v. Soest, Alpina Hagl., Fontana v. Soest and Cucullata v. Soest, all from alpine localities in Europe. No previous cytological work is known for agamospecies in the last four sections. Two small chromosome types and the occurrence of accessory chromosomes are described for the first time in Taraxacum. Sibling karyotypes were found to be invariable, but extensive karyotypic variation was found between samples, even intraspecifically. Karyotypes were compared by means of a “karyotype similarity index”. Samples with a high overall similarity tended to have smaller chromosomes. Eight species exhibited regular chromosome sets, the remainder being irregular. The nature of the origin of the latter is discussed in relation to the origin of agamospecies in the genus.     

The origin of Taraxacum agamospecies

The genus Taraxacum is readily divided into "primitive" and "advanced" forms, on morphological and cytological criteria. It is thought that the genus arose in the west Himalayas during the Cretaceous and that apomixis arose at an early stage by means of polyploidy, precocious embryony and asynapsis in the female meiosis. Advances of sexual primitive types and "precursor" types west into Europe were paralleled by the spread of arctic-alpine types into many regions of the world. During the Pleistocene the precursor types are thought to have generated the widespread advanced section Ceratophora , which gave rise to many of the advanced species after the last glacial period by hybridizing with primitive and precursor sexuals, thus "fixing" a hybrid swarm as apomicts.     

Physiological Studies in Plant Nutrition: XVIII. Some Aspects of Nitrogen Metabolism in Barley and other Plants in Relation to Potassium Deficiency

Barley was grown in water and sand culture using a variety ofnutrient solutions, the most important variable being potassiumsupply. The diamine putrescine, which is not normally foundin this plant in appreciable amounts, is present in the potassium-deficientseedling and accumulates during its growth. Maximum accumulationcoincides with the development of the severe symptoms associatedwith advanced deficiency. Putrescine occurs at an earlier stagein potassium-deficient plants whose nitrate and phosphate aresupplied as ammonium salts than in those to which the correspondingcalcium salts are given. It is found less abundantly in theroots than in the tops. It is absent from protein hydrolysates. A leaf necrosis characteristic of potassium-deficiency is inducedby feeding putrescine to barley having a high potassium status;after prolonged feeding the appearance of such plants suggestssevere potassium starvation. The putrescine is slowly utilized,and at the same time an unidentified substance is produced.What seems to be the same substance appears in quantity in high-potassiumred clover during the course of rapid utilization of administeredputrescine. It also occurs naturally in potassium-deficientred clover. When potassium is supplied to potassium-deficientbarley in which putrescine has accumulated, the amine soon disappears.Application of either rubidium or sodium also leads to a reductionin putrescine, though to a lesser extent, rubidium being themore effective element. Under conditions of extreme potassium-deficiency wheat and redclover also accumulate putrescine. The free amino-acid compositionof the wheat then bears a striking resemblance to that of deficientbarley.     

Genetic evidence from Indian red jungle fowl corroborates multiple domestication of modern day chicken

Background  

Domestication of chicken is believed to have occurred in Southeast Asia, especially in Indus valley. However, non-inclusion of Indian red jungle fowl (RJF), Gallus gallus murghi in previous studies has left a big gap in understanding the relationship of this major group of birds. In the present study, we addressed this issue by analyzing 76 Indian birds that included 56 G. g. murghi (RJF), 16 G. g. domesticus (domestic chicken) and 4 G. sonneratii (Grey JF) using both microsatellite markers and mitochondrial D-loop sequences. We also compared the D-loop sequences of Indian birds with those of 779 birds obtained from GenBank.     

Restoring lakes by using artificial plant beds: habitat selection of zooplankton in a clear and a turbid shallow lake

1. Return of large‐bodied zooplankton populations is of key importance for creating a shift from a turbid to a clear‐water state in shallow lakes after a nutrient loading reduction. In temperate lakes, recovery is promoted by submerged macrophytes which function as a daytime refuge for large zooplankton. However, recovery of macrophytes is often delayed and use of artificial plant beds (APB) has been suggested as a tool to enhance zooplankton refuges, thereby reinforcing the shift to a clear‐water state and, eventually, colonisation of natural plants. 2. To further evaluate the potential of APB in lake restoration, we followed the day–night habitat choices of zooplankton throughout summer in a clear and a turbid lake. Observations were made in the pelagic and littoral zones and in APB in the littoral representing three different plant densities (coverage 0%, 40% and 80%). 3. In the clear lake, the zooplankton (primarily Daphnia) were mainly found in the pelagic area in spring, but from mid‐May they were particularly abundant in the APB and almost exclusively so in mid‐June and July, where they appeared in extremely high densities during day (up to 2600 ind. L⁻¹). During night Daphnia densities were overall more equally distributed between the five habitats. Ceriodaphnia was proportionally more abundant in the APB during most of the season. Cyclopoids were more abundant in the high APB during day but were equally distributed between the five habitats during night. 4. In the turbid lake, however, no clear aggregation was observed in the APB for either of the pelagic genera (Daphnia and Bosmina). This may reflect a higher refuge effect in the open water due to the higher turbidity, reduced ability to orient to plant beds and a significantly higher fish density (mainly of roach, Rutilus rutilus, and perch, Perca fluviatilis) in the plant beds than in the clear lake. Chydorus was found in much higher proportions among the plants, while cyclopoids, particularly the pelagic Cyclops vicinus, dominated in the pelagic during day and in the pelagic and high density plants during night. 5. Our results suggest that water clarity is decisive for the habitat choice of large‐bodied zooplankton and that introduction of APB as a restoration measure to enhance zooplankton survival is only a useful tool when water clarity increases following loading reduction. Our results indicate that dense APB will be the most efficient.     

Harmonised Australian Reference Intervals for Serum PINP and CTX in Adults

Bone turnover markers (BTMs) are classified as either formation or resorption markers. Their concentrations in blood or urine of adults are considered to reflect the rate of bone remodelling and may be of use in the management of patients with bone disease. Major inter-method differences exist for BTMs, and harmonisation of methods is currently being pursued at an international level. Based on published data, this article describes age- and sex-specific Australian consensus reference intervals for adults for serum procollagen type I amino-terminal propeptide (s-PINP) and serum β-isomerised carboxy-terminal cross-linking telopeptide of type I collagen (s-CTX).