The importance of nest cleaning in egg rejection behaviour of great reed warblers Acrocephalus arandinaceas

We tested the importance of nest cleaning in egg rejection behaviour of the great reed warbler Acrocephalus arundinaceus in a highly parasitised population in which about 64% of nests are parasitised by the common cuckoo Cuculus canorus . Three types of objects of the same weight, texture and colour but with different shapes (dummy cuckoo eggs, sticks and disks) were placed into great reed warbler nests. We investigated the response of hosts in two stages of breeding: pre-incubation when the risk of brood parasitism is high, and during incubation when the risk of parasitism is low. The dummy cuckoo eggs were rejected less often than the other objects in both breeding stages, although we did not find any difference in the frequency of rejection between pre-incubation and incubation. We integrate these results into current views on the evolution of host–parasite interactions, and propose a hierarchical concept to understand egg rejection behaviour: (1) hosts reject all non-egg shaped objects as a general cleaning mechanism; (2) adaptations for the hosts' ability to recognise their own eggs allows them to distinguish these eggs from similar objects and parasitic eggs.     

Sterols and frost hardening of winter rape

Winter rape ( Brassica napus L., var. olifera cv. Górczanski) seedlings were exposed to hardening conditions and the content and composition of free sterols as well as the ratio of free sterols to total phospholipids were determined. There was a reduction in free sterol content in the leaves at the most advanced stage of hardening. The ratio of free sterol to total phospholipids was significantly reduced by hardening due to a decrease in the level of the former and an increase in that of the latter compounds. There was a negative correlation between this ratio and the temperature at which half of the seedlings died. Thus, adaptation of membranes to temperature takes place also at the level of sterol-phospholipid interactions. Exposing seedlings already hardened to freezing temperatures caused injury higher than 50%, and brought about a drastic increase in the level of free sterols and an elevation in the ratio of free sterols to phospholipids. The results are discussed in terms of a possible role of the molecular architecture of membranes in surviving at subzero temperatures.     

Studies on the terminal stages of immune hemolysis. VI. Osmotic blockers of differing Stokes' radii detect complement-induced transmembrane channels of differing size.

We have previously shown that 0.1 M EDTA could be used to distinguish functionally different transmembrane channels produced during complement-(C) mediated hemolysis of E. In this paper we have studied the ability of sugars of varying Stokes' radii to prevent hemoglobin release from E intermediates whose lysis was inhibitable or not inhibitable by EDTA. On the basis of these experiments we propose that the inhibition of E transformation by high molarity EDTA occurs by virtue of the size of the EDTA molecule in solution. Studies on the effect of EDTA on red cell lysis induced by polyene antibiotics that form transmembrane channels of a defined size support this conclusion. The results of these experiments were interpreted to mean: 1) The EDTA inhibitable lesion of E has a smaller effective radius than the noninhibitable lesion; 2) the effective radius of the smallest lesion that yields a lytic site was less than 3.6 A; 3) the lesions produced in the red cell membrane by C are not uniform but vary in size depending on the C9 to SACl-8 ratio used to produce E.     

Studies on the interaction between protein A and immunoglobulin G. I. Effect of protein A on the functional activity of IgG.

Staphylococcal protein (A (PA) and IgG anti-Forssman immunoglobulin formed complexes that behaved functionally like IgM in their ability to lyse sheep erythrocytes (E) in the presence of whole guinea pig complement (GPC) and to fix purified guinea pig C1. Concanavalin A, a plant lectin that inhibited IgM but not IgG hemolytic activity, inhibited the hemolytic activity of IgG-protein A complexes that behaved like IgM but had no effect on complexes that behaved functionally like IgG. Since Con A is known to bind specifically to glucose and mannose residues, our results suggested that the interaction of protein A with the Fc region of IgG led to exposure of sugar moieties that may participate in complement (C) binding. The production of IgM-like complexes depended on the ratio of protein A to IgG and the empirical formula of these IgM-like complexes was found to be [(IgG)2PA]n. As the ratio of PA to IgG was increased, the resulting complexes tended to behave functionally like IgG but with reduced hemolytic activity and C1 fixing ability. Furthermore, the binding of C1 to EIgG was inhibited by PA and the binding of PA to EIgG was inhibited by C1 indicating that the binding sites for C1 and PA were located near each other or were identical. Our results offer a reasonable explanation for the reported effects of PA or mixtures of PA and IgG in vitro and in vivo.     

Frequency of large granular lymphocytes in peripheral blood of healthy persons and breast cancer patients

The frequency of large granular lymphocytes (LGL) in the peripheral blood of healthy persons (n = 56) and breast cancer patients (31 cases with stage-I and -II disease and 42 cases with stage-III and -IV disease) was studied. The frequency of LGL in peripheral blood was significantly depressed in cancer patients, and particularly in patients with advanced breast cancer.     

Distance measurements using paramagnetic ion-induced relaxation in the saturation transfer electron spin resonance of spin-labeled biomolecules: Application to phospholipid bilayers and interdigitated gel phases

The saturation transfer electron spin resonance (STESR) spectra of spin-labeled phosphatidylcholines in gel phase lipid bilayers are shown to be sensitive to dipolar spin-spin interactions with paramagnetic ions in the aqueous phase. The reciprocal integrated intensity of the STESR spectrum is linearly dependent on aqueous Ni²⁺ ion concentration, hence, confirming the expectation that the STESR intensity is directly proportional to the spin-lattice relaxation time of the spin label. The gradient of the relaxation rate with respect to Ni²⁺ ion concentration decreases strongly with the position of the nitroxide group down the sn-2 chain of the spin-labeled lipid and is consistent with a 1/R³ dependence on the distance, R, from the bilayer surface. The values derived for the dimensions of the bilayer and lipid molecules in the case of dipalmitoyl phosphatidylcholine (DPPC) are in good agreement with those available from x-ray diffraction studies. Allowance for the multibilayer nature of the DPPC dispersions gives an estimate of the water layer thickness that is also consistent with results from x-ray diffraction. The profile of the paramagnetic ion-induced relaxation is drastically changed with DPPC dispersions in glycerol for which the lipid chains are known to be interdigitated in the gel phase. The terminal methyl groups of the lipid chains are located approximately in register with the C-3 atoms of the sn-2 chain of the oppositely oriented lipid molecules in the interdigitated phase. The thickness of the lipid layer and the effective thickness of the lipid polar group are reduced by ~40% in the interdigitated phase as compared with the bilayer phase. The calibrations of the distance dependence established by use of spin labels at defined chain positions should be applicable to STESR measurements on other biological systems.     

Lectinomics I. Relevance of exogenous plant lectins in biomedical diagnostics

This review focuses on utilization of plant lectins as medical diagnostic reagents and tools. The lectin-related diagnostic is aimed at detection of several diseases connected to alteration of the glycosylation profiles of cells and at identification of microbial and viral agents in clinical microbiology. Certain lectins, proposed for or used as diagnostic tools could even recognize those cellular determinants, which are not detected by available antibodies. Broad information is presented on the lectinomics field, illustrating that lectin diagnostics might become practical alternative to antibody-based diagnostic products. In addition, the rising trend of lectin utilization in biomedical diagnostics might initiate a development of innovative methods based on better analytical technologies. Lectin microarray, a rapid and simple methodology, can be viewed as an example for such initiative. This technology could provide simple and efficient screening tools for analysis of glycosylation patterns in biological samples (cellular extracts, tissues and the whole cells), allowing thus personalized detection of changes associated with carbohydrate-related diseases.     

Kinetics and dynamics of annealing during sub-gel phase formation in phospholipid bilayers: A saturation transfer electron spin resonance study

The saturation transfer electron spin resonance (STESR) spectra of spin-labeled phosphatidylcholine have been used to follow the kinetics of conversion from the gel phase to the sub-gel phase in aqueous bilayers of dipalmitoyl phosphatidylcholine. This is a simple, well-defined model system for lipid domain formation in membranes. The integrated intensity of the STESR spectrum from the chain-labeled lipid first increases and then decreases with time of incubation in the gel phase at 0°C. The first, more rapid phase of the kinetics is attributed to the conversion of germ nuclei to growth nuclei of the sub-gel phase. The increase in STESR intensity corresponds to the reduction in chain mobility of spin labels located in the gel phase at the boundaries of the growth nuclei and correlates with the increase in the diagnostic STESR line height ratios over this time range. The second, slower phase of the kinetics is attributed to growth of the domains of the sub-gel phase. The decrease in STESR intensity over this time regime corresponds to exclusion of the spin-labeled lipids from the tightly packed sub-gel phase and correlates quantitatively with calibrations of the spin label concentration dependence of the STESR intensity in the gel phase. The kinetics of formation of the sub-gel phase are consistent with the classical model for domain formation and growth. At 0°C, the half-time for conversion of germ nuclei to growth nuclei is ∼7.7 h and domain growth of the sub-gel phase is characterized by a rate constant of 0.025 h^-1. The temperature dependence of the STESR spectra from samples annealed at 0°C suggests that the subtransition takes place via dissolution of sub-gel phase domains, possibly accompanied by domain fission.     

A new dermatophyte,Thallomicrosporon kuehnii Benedek, 1963

Summary A new species of a dermatophyte,Thallomicrosporon kuehnii Benedek, 1963, is described. In contradistinction to all other known dermatophytes, it reproduces exclusively by thallospores: 1) large, fusiform, macroconidia-like structures, 2) arthrospores and, 3) chlamydospores. Microconidia are present, rodlike or pyriform. The elicitation of a perfect form of fructification in hair-on-soil cultures was unsuccessful.

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Zusammenfassung Eine neue Art der Dermatophyten,Thallomicrosporon kuehnii Benedek, 1963, wird beschrieben. Sie unterscheidet sich von allen anderen Hauptilzen durch den Umstand, dass sie sich ausschliesslich durch Thallosporen reproduziert: 1) Formen, ähnlich fusiformen Makrokonidien; 2) Arthrosporen und 3) Chlamydosporen. Mikrokonidien werden gebildet. Das Hervorbringen der perfekten Phase der Fruktifikation in Kulturen von Haar an Humus ist nicht gelungen.

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Résumé Une espèce nouvelle des dermatophytes,Thallomicrosporon kuehnii Benedek, 1963, est présentée. Elle est distincte de tous les autres dermatophytes par le fait de sa reproduction exclusive par des thallospores: 1) des structures imitant des macroconidies fusiformes; 2) des arthrospores et 3) des chlamydospores. Des microconidies sont présentes. L'élicitation de la phase perfecte de fructification en culture des poils en sol n'a pas réussi.