The bark of Robinia pseudoacacia contains a complex mixture of lectins.Characterization of the proteins and the cDNA clones.

Two lectins were isolated from the inner bark of Robinia pseudoacacia (black locust). The first (and major) lectin (called RPbAI) is composed of five isolectins that originate from the association of 31.5- and 29-kD polypeptides into tetramers. In contrast, the second (minor) lectin (called RPbAII) is a hometetramer composed of 26-kD subunits. The cDNA clones encoding the polypeptides of RPbAI and RPbAII were isolated and their sequences determined. Apparently all three polypeptides are translated from mRNAs of approximately 1.2 kb. Alignment of the deduced amino acid sequences of the different clones indicates that the 31.5- and 29-kD RPbAI polypeptides show approximately 80% sequence identity and are homologous to the previously reported legume seed lectins, whereas the 26-kD RPbAII polypeptide shows only 33% sequence identity to the previously described legume lectins. Modeling the 31.5-kD subunit of RPbAI predicts that its three-dimensional structure is strongly related to the three-dimensional models that have been determined thus far for a few legume lectins. Southern blot analysis of genomic DNA isolated from Robinia has revealed that the Robinia bark lectins are the result of the expression of a small family of lectin genes.     

Investigation of Local Ethylene Emission from Intact Cherry Tomatoes by Means of Photothermal Deflection and Photoacoustic Detection

The function of the coronet region of the cherry tomato (Lycopersicon esculentum Cherry) as the main emission channel for ethylene was investigated. Ethylene was measured employing two laser-based detection systems, the photothermal deflection instrument and the photoacoustic detection setup. It is possible to detect minimum ethylene concentrations of 1 nL L-1 locally and rapidly with the first instrument and concentrations of 6 pL L-1 in a continuous flow system with the second setup. The continuous flow system makes it possible to change the air composition and to monitor its influence on the ethylene production of the tomato. The response times of the two instruments are 30 s and 4 min, respectively. The local character of the measurements makes it possible to determine the emission sites of the gaseous plant hormone ethylene and their relative importance. Transient anoxic conditions stop production of ethylene; return to aerobic conditions shows the evolution of the accumulated ethylene precursor 1-aminocyclopropane-1-carboxylic acid and its renewed production on the measured ethylene emission, with a time resolution of several minutes. Temporarily sealing the main emission channel yields results comparable to anoxia.     

A genetic map of potato (Solanum tuberosum) integrating molecular markers,including transposons,and classical markers

A genetic map of potato (Solanum tuberosum L.) integrating molecular markers with morphological and isozyme markers was constructed using a backcross population of 67 diploid potato plants. A general method for map construction is described that differs from previous methods employed in potato and other outbreeding plants. First, separate maps for the female and male parents were constructed. The female map contained 132 markers, whereas the male map contained 138 markers. Second, on the basis of the markers in common the two integrated parental maps were combined into one with the computer programme JoinMap. This combined map consisted of 175 molecular markers, 10 morphological markers and 8 isozyme markers. Ninety-two of the molecular markers were derived from DNA sequences flanking either T-DNA inserts in potato or reintegrated maize transposable elements originating from these T-DNA constructs. Clusters of distorted segregation were found on chromosomes 1,2,8 and 11 for the male parent and chromosome 5 for both parents. The total length of the combined map is 1120 cM.     

Stimulation of the Alternative Pathway by Succinate and Malate

Stimulation of the cyanide-resistant oxidation of exogenous NADH in potato (Solanum tuberosum L. cv Bintje) tuber callus mitochondria was obtained with succinate, malate, and pyruvate. Half-maximal stimulation was observed at a succinate or malate concentration of 3 to 4 mM, which is considerably higher than that found for pyruvate (0.128 mM). No effect of succinate or malate addition was found when duroquinone was the electron acceptor. Duroquinol oxidation via the alternative pathway was poor and not stimulated by organic acids. Under stimulating conditions, no swelling or contraction of the mitochondria could be observed. Conversely, variation of the osmolarity did not affect the extent of stimulation. However, the assay temperature had a significant effect: no stimulation occurred at temperatures below 16 to 20[deg]C. Membrane fluidity measurements showed a phase transition at about 17[deg]C. Ubiquinone reduction levels were not significantly higher in the presence of succinate and malate, but the kinetics of the alternative oxidase were changed in a way comparable to that found for stimulation by pyruvate. At low temperatures the alternative oxidase displayed "activated" kinetics, and a role for membrane fluidity in the stimulation of the alternative pathway by carboxylic acids is suggested.     

Relation between stallion sperm binding to homologous hemizonae and fertility

The hemizona assay (HZA) has been developed as a diagnostic test to predict the fertilisation potential of human spermatozoa. The aim of this study was to develop an HZA for stallion spermatozoa and to investigate a possible relationship between fertility and the outcome of the HZA in this species. Equine oocytes were obtained from ovaries collected at a slaughterhouse and by transvaginal, ultrasound-guided follicle aspiration. They were then denuded from cumulus cells and stored in salt solution at 4 degrees C until use. On the day of the experiments the oocytes were bisected, thus providing 2 equal matching hemizonae from each oocyte. Semen samples from Dutch Warmblood stallions with known fertility data were used to assess the number of spermatozoa bound to the outer side of the hemizona after incubation in vitro. Sperm binding to matching hemizonae of a particular stallion was similar and confirmed the feasibility of using the HZA for the horse. Sperm hemizona binding capacity of 10 pairs of stallions was compared by incubating 1 hemizona with the semen of a stallion and the matching hemizona with the semen of another stallion from the same stud farm. Five matching pairs of hemizonae were used for each pair of stallions. There was a significant relationship between the mean number of spermatozoa bound to matching hemizonae and the fertility indices of stallions from each stud farm (P < 0.0001). It is concluded that HZA can be used as a valuable parameter in stallion semen analysis.     

Seleno-lactobacillus

Lactic acid bacteria are nonpathogenic bacteria commonly used in food processing. An evaluation was made of the capacity to concentrate selenium in species of Lactobacillus. A selenium concentration of 1 μg/mL in the culture medium yielded in a bacterial content of 400 μg/g dry biomass. Dialysis and TCA precipitation experiments of a native intracellular extract proved that at least 80% of the total selenium is associated with organic molecules. Seleno-cysteine was identified as the only seleno-amino acid present in the intracellular selenoproteins. This study shows that species of the lactic acid bacteria are able to concentrate selenium intracellular as seleno-cysteine, which could be applied in supplementation studies.     

Interleukin-12 gene expression after viral infection in the mouse.

Interleukin-12 is a lymphokine that triggers gamma interferon secretion by various cells and differentiation of T-helper lymphocytes towards the Th1 subtype. Since viruses are potent inducers of gamma interferon production and elicit immune responses most probably mediated by Th1 cells, like B-cell immunoglobulin G2a secretion, we analyzed interleukin-12 message expression after infection of mice with lactate dehydrogenase-elevating virus, mouse hepatitis virus, and mouse adenovirus. Our results indicated that the message for the p40 component of interleukin-12 was transiently increased shortly after infection. Interleukin-12 was expressed mainly by macrophages. Therefore, production of interleukin-12 might constitute the initial event that would determine the subsequent characteristics of the immune response elicited by viral infections.