Effects of protective agents on membrane fluidity of freeze-dried Lactobacillus delbrueckii ssp. bulgaricus

AIMS: To evaluate the effect of protective agents upon survival of Lactobacillus delbrueckii ssp. bulgaricus during freeze-drying and storage, and selective amino acids on cell membrane fluidity. METHODS AND RESULTS: The protective effect of amino-acids and sugars at different concentrations was studied by determining the viability of lyophilized cells after storage under air at 30 degrees C. Survival following freeze-drying was improved by all compounds. During storage, neither proline nor maltose had protective effects on lyophilized Lact. delbrueckii ssp. bulgaricus. Glutamate 5% and aspartate 5% showed similar protection capability during freeze-drying (94-95%) and after storage (92-99%). Fluorescence probes (DPH and TMA-DPH) were used to study the effect of both amino acids on membrane fluidity. Polarization decreased with increasing concentrations of glutamate or aspartate. Lowest values were observed with TMA-DPH. CONCLUSIONS: Glutamate 5% and aspartate 5% allowed maintaining high viability rates during freeze-drying and storage of Lact. delbrueckii ssp. bulgaricus because of an increase of the membrane fluidity by inserting in the interfacial region of bacterial plasma membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: These results show the first evidence of the mechanisms underlying glutamate and aspartate as lyoprotectors.     

High-throughput sequencing of African <Emphasis Type="Italic">chikanda</Emphasis> cake highlights conservation challenges in orchids

Chikanda is a traditional dish made with wild-harvested ground orchid tubers belonging to three orchidioid genera, Disa, Satyrium and Habenaria, all of which are CITES appendix II-listed. Identification of collected orchid tubers is very difficult and documentation of constituent species in prepared chikanda has hitherto been impossible. Here amplicon metabarcoding was used in samples of six prepared chikanda cakes to study genetic sequence diversity and species diversity in this product. Molecular operational taxonomic unit identification using similarity-matching reveals that species of all three genera were present in the chikanda samples studied. Disa was present in all of the samples, Satyrium in five out of six and Habenaria in one of the samples, as well as a number of other plants. The fact that each sample contained orchids and the presence of a wide variety of species from all genera in this traditional dish raise serious concerns about the sustainability of this trade and the future of wild orchid populations in the main harvest areas. This proof-of-concept study shows that Ion-Torrent PGM is a cost-effective scalable platform for metabarcoding using the relatively long nrITS1 and nrITS2 regions. Furthermore, nrITS metabarcoding can be successfully used for the detection of specific ingredients in a highly-processed food product at genus level, and this makes it a useful tool in the detection of possible conservation issues arising from commercialized trade or processed plant products.     

The color of greater flamingo feathers fades when no cosmetics are applied

Greater flamingos use cosmetic coloration by spreading uropygial secretions pigmented with carotenoids over their feathers, which makes the plumage redder. Because flamingos inhabit open environments that receive direct solar radiation during daytime, and carotenoids bleach when exposed to solar radiation, we expected that the plumage color would fade if there is no maintenance for cosmetic purposes. Here, we show that the concentrations of pigments inside feathers and on the surface of feathers were correlated, as well as that there was a correlation between the concentrations of pigments in the uropygial secretions and on the surface of feathers. There was fading in color (becoming less red) in feathers that received direct solar radiation when there was no plumage maintenance, but not so in others maintained in darkness. When we controlled for the initial color of feathers, the feathers of those individuals with higher concentration of pigments on the feather surfaces were those that lost less coloration after experimental exposure of feathers to sunny conditions. These results indicate that exposure to sunlight is correlated with the fading of feather color, which suggests that individuals need to regularly apply makeup to be more colorful. These results also reinforce the view that these birds use cosmetic coloration as a signal amplifier of plumage color. This may be important in species using highly variable habitats, such as wetlands, since the conditions experienced when molting may differ from those when the signal should be functional, usually months after molting.     

Gas exchange patterns of Pterostichus niger (Carabidae) in dry and moist air

Gas exchange patterns of adult male Pterostichus niger Schaller after hydration (i.e. given access to food and water) are compared in dry air [5–7% relative humidity (RH)] and moist air (90–97% RH) by means of flow‐through CO₂ respirometry combined with infrared probe actography. Of thirty beetles examined, slightly more than 50% showed continuous gas exchange and are not considered further. Of the remaining beetles, the majority (approximately 71%) display a pattern of cyclic gas exchange in both dry and moist air (i.e. CO₂ gas is released in bursts, with a low level of CO₂ release during the interburst periods). A minority of the beetles (four out of 30) are found to exhibit discontinuous gas exchange in both dry and moist air; this is characterized by three clearly separated states of the spiracles: closed (C), flutter (F) and open (O) phases. The pattern of cyclic gas exchange is associated with weak abdominal pulsations. After switching from moist to dry air, a small modulation of the discontinuous gas exchange cycles (maximum mean CO₂ production rate) occurs, providing no clear support for the hygric theory of discontinuous gas exchange in this species (i.e. that it serves to restrict respiratory water loss).     

Platelet aggregation, lipids and excretion of catecholamines after acute physical exercise in patients with myocardial infarction

The effect of acute physical exercise and a four-month conditioning program on cardiovascular risk factors was investigated in patients with myocardial infarction. The bicycle exercise testing caused a moderate rise in urinary epinephrine, serum cholesterol and HDL cholesterol levels. The changes in platelet aggregation and urinary catecholamines were markedly greater in the group with exercise induced ischaemic changes. Under the effect of the conditioning program a significant improvement in the performance capacity and circulatory response could be observed. The direction of changes in platelet aggregation and in the lipid parameters were favourable too.     

Protandrous migration and variation in morphological characters in Emberiza buntings at an East Asian stopover site

The effect of the timing of spring migration on reproductive success differs between the sexes. As a consequence, various sex‐specific tactics relating to the timing of migration have evolved in migratory avian groups. Various hypotheses have been proposed to explain differential migration to breeding or wintering grounds, and inter‐ and intrasexual size differences are often considered one of the proximate mechanisms. We investigated arrival patterns in the spring by individuals of each sex, sexual size dimorphism and related morphological variables, and the relationship between size variation and arrival date in five bunting species that passed through an East Asian migratory flyway stopover site in 2006–08. Males of all the study species arrived before females, and significant sexual dimorphism was observed. Several morphological characters, including total length, wing‐length and tail‐length, contributed to the size variation. Although larger males arrived earlier, there was no relationship between arrival date and size in females. Our study confirmed that East Asian buntings display a discriminated protandrous migration pattern at the stopover site as well as at the breeding grounds. This is consistent with the view that larger body size in males is favoured due to its association with early arrival to help ensure access to the best resources and hence enhanced mating success.     

Characterization of self-association and heteroassociation of bacterial cell division proteins FtsZ and ZipA in solution by composition gradient-static light scattering

We have characterized the self-association of FtsZ in its GDP-bound state (GDP-FtsZ) and the heteroassociation of FtsZ and a soluble recombinant ZipA (sZipA) lacking the N-terminal transmembrane domain by means of composition gradient-static light scattering (CG-SLS) and by measurement of sedimentation equilibrium. CG-SLS experiments at high ionic strengths and in the presence of 5 mM Mg(2+) show that, while FtsZ self-associates in a noncooperative fashion, sZipA acts as a monomer. CG-SLS data obtained from mixtures of FtsZ (A) and sZipA (B) in the presence of Mg(2+) are quantitatively described by an equilibrium model that takes into account significant scattering contributions from B, A(1), A(2), A(3), A(4), A(5), A(6), A(1)B, A(2)B, A(3)B, and A(4)B. However, in the absence of Mg(2+) (with EDTA), the data are best explained by an equilibrium model in which only B, A(1), A(2), A(3), A(1)B, and A(2)B contribute significantly to scattering. The best-fit molecular weights of monomeric A and B are in good agreement with values calculated from amino acid composition and with values obtained from sedimentation equilibrium. The latter technique also confirmed the interaction between sZipA and GDP-FtsZ. Moreover, the association model that best describes the CG-SLS data is in qualitative agreement with the sedimentation data. From these results, it follows that the binding of sZipA to GDP-FtsZ is of moderate affinity and does not significantly affect the interactions between FtsZ monomers. Under the working conditions used, only one sZipA binds to FtsZ oligomers with a length of six at most. The observed behavior would be compatible with FtsZ fibrils being anchored in vivo to the bacterial inner plasma membrane by substoichiometric binding of membrane-bound ZipA.     

Ultrastructure and light microscopical study of a Leydig cell tumor of the testis associated with bilateral gynaecomastia

Light and electronmicroscopic study of a Leydig cell testicular tumor in an 18-year-old male is presented. Bilateral gynaecomastia and normal hormonal blood levels were found. Emphasis on the diagnostic value of electronmicroscopy is remarked upon, based on the following ultrastructural characteristics of the cells; 1) Ovoid shaped nuclei with ondulating contours and dispersed and homogeneous chromatin, 2) Rich agranular endoplasmic reticulum with frequent special modifications, such as membranous whorls with a central cytoplasmic mass or lipid droplets, 3) Numerous mitochondria with occasional tubular cristae, 4) Numerous lipid vacuoles. Other structures also identified in this tumor are Reinke crystalloids, cytoplasmic microbodies, myelin figures, gap-type junctional complexes and paracrystalline inclusions of Payer type E, which are less common.