NESTMATE RECOGNITION AND KIN RECOGNITION IN ANTS

Abstract  All ants (Hymenoptera, Formicidae) are highly eusocial insects that are characterized by reproductive division of labor with sterile castes (worker and soldier) helping fertile castes (queen and male) to reproduce.
Ant societies, like other complex animal societies, have developed a sophisticated communication system, in which recognition behaviors are frequently involved Recognition abilities allow individuals to orient and modulate their behaviors effectively and appropriately in response to the characteristics andlor signals expressed by other organisms. Among recognition behaviors, nestmate recognition and kin recognition mechanisms have attracted great attention of sociobiologists, ecologists, insect physiologists and biochemists since 1970's. This is parallel with the popularization of Hamilton's kin selection theory. The present paper aims at reviewing the current understanding on nestmate/kin recognition in ants. This review consists of three parts. The first part concerns the diversity of recognition behaviors and their ecological implications with emphasis on nestmatelkin recognition; in the second part, the current understandings on the mechanism of nestmatelkin recognition are outlined; and in the third part, we discuss the ontogenetic development of nestmate recognition behavior and naturally mixed colonies. The study of the integration mechanism of social parasite may provide heuristic clues to the understanding of kin/nestmate recognition system.     

Lignin degradeation by white rot fungi

Abstract. The wood-degrading white-rot fungus Phanerochaete chrysosporium , has been the subject of intensive research in recent years and, based upon isolation of the extracellular enzyme ligninase, major advances have now been made toward elucidating the mechanism by which this fungus degrades lignin. From these developments, a model emerges which could explain the process by which wood-degrading fungi in general, attack lignin.     

Role of nuclear analytical probe techniques in biological trace-element research

Many biomedical experiments require the qualitative and quantitative localization of trace elements with high sensitivity and good spatial resolution. The feasibility of measuring the chemical form of the elements, the time course of trace element metabolism, and conducting experiments in living biological systems are also important requirements for biological trace element research. Nuclear analytical techniques that employ ion or photon beams have grown in importance in the past decade and have led to several new experimental approaches. Some of the important features of these methods are reviewed here along with their role in trace element research. Examples of their use are given to illustrate potential for new research directions. It is emphasized that the effective application of these methods necessitates a closely integrated multidisciplinary scientific team.     

Transformation of the forage legume Trifolium repens L. using binary Agrobacterium vectors

A system was established for introducing cloned genes into white clover (Trifolium repens L.). A high regeneration white clover genotype was transformed with binary Agrobacterium vectors containing a chimaeric gene which confers kanamycin resistance. Transformed kanamycin resistant callus was obtained by culturing Agrobacterium inoculated stolon internode segments on selective medium. The kanamycin resistance phenotype was stable in cells and in regenerated shoots. Transformation was confirmed by the expression of an unselected gene, nopaline synthase in selected cells and transgenic shoots and by the detection of neomycin phosphotransferase II enzymatic activity in kanamycin resistant cells. Integration of vector DNA sequences into plant DNA was demonstrated by Southern blot hybridisation.     

The effect of diffusion and convection on the rate of transfer of solutes across an interface

The transfer of substances across the interface between water and a membrane or between water and a solvent occurs in series with transport up to and away from the interface. These processes have been difficult to resolve. Recently D. M. Miller (Biochim Biophys Acta 856: 27–35, 1986) has used a moving drop technique to measure the rates of transfer of short-chain alcohols and tritiated water between water andn-octanol. This technique produces equivalent unstirred layers which are less than about 10 m thick. Based on the trends in the observed rates of phase transfer, he proposes that the transfer is limited by the actual interfacial step. If so, water-oil interfacial transfer would be sufficiently slow to limit the rate of permeation of lipid membranes by these substances. It is shown here that the observed rates of phase transfer can be explained quantitatively if they are limited by convection or by diffusion across the combination of 5–10 m unstirred layers both inside and outside the moving drops. For water, comparison of the observed rates with the rate of evaporation from a clean surface, suggests that the interfacial step at the water-octanol interface is not rate-limiting.     

A finite-difference electromagnetic deposition/thermoregulatory model: comparison between theory and measurements

The rate of the electromagnetic energy deposition and the resultant thermoregulatory response of a block model of a squirrel monkey exposed to plane-wave fields at 350 MHz were calculated using a finite-difference procedure. Noninvasive temperature measurements in live squirrel monkeys under similar exposure conditions were obtained using Vitek probes. Calculations exhibit reasonable correlation with the measured data, especially for the rise in colonic temperature.     

Ionic balance,proton efflux,nitrate reductase activity and growth ofHippophaë rhamnoides L. ssp.rhamnoides as influenced by combined-N nutrition or N2 fixation

Growth of 2-month-old nonnodulatedHippophaë rhamnoides seedlings supplied with combined N was compared with that of nodulated seedlings grown on zero N. Plant growth was significantly better with combined N than with N₂ fixation and, although not statistically significant for individual harvests, tended to be highest in the presence of NH ₄ ⁺ , a mixture of NH ₄ ⁺ and NO ₃ ^? producing the highest yields. Growth was severely reduced when solely dependent on N₂ fixation and, unlike the combined-N plants, shoot to root ratios had only slightly increased after an initial decrease. An apparently insufficient nodule mass (nodule weight ratio <5 per cent) during the greater part of the experimental period is suggested as the main cause of the growth reduction in N₂-fixing plants. Thein vivo nitrate reductase activity (NRA) of NO ₃ ^? dependent plants was almost entirely located in the roots. However, when grown with a combination of NO ₃ ^? and NH ₄ ⁺ , root NRA was decreased by approximately 85 per cent.H. rhamnoides demonstrated in the mixed supply a strong preference for uptake of N as NH ₄ ⁺ , NO ₃ ^? contributing only for approximately 20 per cent to the total N assimilation. Specific rates of N acquisition and ion uptake were generally highest in NO ₃ ^? +NH ₄ ⁺ plants. The generation of organic anions per unit total plant dry weight was approximately 40 per cent less in the NH ₄ ⁺ plants than in the NO ₃ ^? plants. Measured extrusions of H⁺ or OH^? (HCO ₃ ^? ) were generally in good agreement with calculated values on the basis of plant composition, and the acidity generated with N₂ fixation amounted to 0.45–0.55 meq H⁺. (mmol N_org)^?1. Without acidity control and in the presence of NH ₄ ⁺ , specific rates of ion uptake and carboxylate generation were strongly depressed and growth was reduced by 30–35 per cent. Growth of nonnodulatedH. rhamnoides plants ceased at the lower pH limit of 3.1–3.2 and deterioration set in; in the case of N₂-fixing plants the nutrient solution pH stabilized at a value of 3.8–3.9 without any apparent adverse effects upon plant performance. The chemical composition of experimental and field-growing plants is being compared and some comments are made on the nitrogen supply characteristics of their natural sites.     

Prediction of heavy-metal concentrations in mature plants by chemical analysis of seedlings

Five plant species were cultivated on a soil from the Neckar alluvial fan near Heidelberg (FRG) polluted by the emissions of a cement plant. Thallium, cadmium and lead concentrations in seedlings and mature plants were determined by atomic absorption analysis. AdditionallyBrassica napus L.napus was grown on soils containing 5 different concentrations of heavy metals, achieved by mixing two similar soils, from the same area but with different metal concentrations. Thallium and cadmium were shown to be taken up by roots whilst lead which was also absorbed, was deposited mainly on the plant surface. However during cultivation in the winter months, a remarkable deposit of lead via the roots was found. Thallium in the soil from a anthrorogen source was more available to plants than thallium of geological origin. During the lifetime of a plant concentrations of thallium and cadmium were always highest in the seedling. The decrease in metal concentration with maturity depended on the plant species and the element, but was not a function of the metal concentration in the soil.