Physiological response of sugar beet (Beta vulgaris) genotypes to a temporary water deficit, as evaluated with a multiparameter fluorescence sensor

Greenhouse and field experiments were carried out to evaluate the potential of specific fluorescence emission parameters for the detection of a temporary water deficit in selected sugar beet (Beta vulgaris L.) genotypes. Changes in the plant physiology due to reduced water availability were recorded with a multiparameter fluorescence sensor in addition to destructive and non-invasive reference analysis. Our results show that an insufficient water supply is followed by only slight changes of the UV-excited blue fluorescence. However, significant alterations due to desiccation were detected in several chlorophyll fluorescence parameters measured after excitation with UV, green and red light. In the scope of our activities, the relevance of the green light source for the fluorescence excitation became evident and enabled to characterize cultivar-specific reactions during dehydration and re-watering period. A field experiment was conducted to validate the data collected in the greenhouse. As proven, several days of low water supply led to effects similar to those observed in the greenhouse study. Our results indicate that the far-red fluorescence, as well as the simple and complex fluorescence ratios having the chlorophyll fluorescence as basis, is the appropriate parameter to evaluate physiological responses of sugar beet plants exposed to a short-term, temporary water deficit.     

The effect of genotype,media composition,pH and sugar concentrations on oat (<Emphasis Type="Italic">Avena sativa</Emphasis> L.) doubled haploid production through oat × maize crosses

Doubled haploid (DH) technology in oat has not reached the same stage as in other cereals leading to its application in plant breeding. The objective of this investigation was to increase the effectiveness of Avena sativa L. haploid embryo germination obtained by the distant crosses with maize. Developed embryos (obtained from 22 genotypes) were transferred on five germination media: MS (Murashige and Skoog, Physiol Plant 15:473–497, 1962) with 3% sucrose, pH 5.8 (control medium), and 190-2 supplemented with 6 and 9% maltose. The pH of 190-2 was adjusted to 5.5 and 6.0. Of all tested genotypes, 591 haploid embryos were obtained, almost half of them (279) germinated. The rate of haploid embryo germination induced on 190-2 was 6.92%, while in MS it was 3.25%. The sugar and its concentration significantly affected the germination of haploid embryos. The highest percentage of haploid embryo germination (9.11%) and DH lines production (1.64%) was achieved on 190-2 with 9% maltose and pH 6.0. All DH lines are incorporated to breeding programs for the development of new cultivars.     

Immunocytochemical localization of piscidin in mast cells of infected seabass gill

Annual losses of ～5–10% of the juvenile stock of European seabass, Dicentrarchus labrax (L.) in the northern coast of the Adriatic Sea has been attributed to heavy infections of the gill monogenean Diplectanum aequans. Immunocytochemical, light and ultrastructural studies were carried out on seabass naturally parasitized with this monogenean. The site of the worm's attachment was marked by the common presence of haemorrhages and white mucoid exudate. In histological sections, infected gills showed hyperplasia, as well as proliferation of mucous cells and rodlet cells. Disruption and fusion of the secondary lamellae were common in all infected seabass, with several specimens also showing marked inflammation and erosion of the primary and secondary lamellar epithelium. Immunostaining of primary and secondary gill filaments with an antibody against the antimicrobial peptide piscidin 3 (anti-piscidin 3 antibody, anti-HAGR) revealed a subpopulation of mast cells that were positive. Mast cells were both within and outside the blood vessels of the primary and secondary lamellae, and often made intimate contact with vascular endothelial cells. Mast cells were irregular in shape with a cytoplasm filled by numerous electron-dense, membrane-bound granules. Our data provide evidence showing the presence of piscidin 3 in the cytoplasmic granules of an important group of fish inflammatory cells, the mast cells resident in seabass gill tissue. There was no significant difference in the number of HAGR-positive mast cells between infected and uninfected fish (ANOVA, p > 0.05). However, mast cells in parasitized gills usually showed much stronger immunostaining intensity compared to those in unparasitized gills. These data are the first to document a response of piscidins or any other antimicrobial peptide of fish to parasite infection and suggest that mast cells may play a role in certain inflammatory responses without a detectable increase in their numbers.     

Isometric Scaling in Developing Long Bones Is Achieved by an Optimal Epiphyseal Growth Balance

One of the major challenges that developing organs face is scaling, that is, the adjustment of physical proportions during the massive increase in size. Although organ scaling is fundamental for development and function, little is known about the mechanisms that regulate it. Bone superstructures are projections that typically serve for tendon and ligament insertion or articulation and, therefore, their position along the bone is crucial for musculoskeletal functionality. As bones are rigid structures that elongate only from their ends, it is unclear how superstructure positions are regulated during growth to end up in the right locations. Here, we document the process of longitudinal scaling in developing mouse long bones and uncover the mechanism that regulates it. To that end, we performed a computational analysis of hundreds of three-dimensional micro-CT images, using a newly developed method for recovering the morphogenetic sequence of developing bones. Strikingly, analysis revealed that the relative position of all superstructures along the bone is highly preserved during more than a 5-fold increase in length, indicating isometric scaling. It has been suggested that during development, bone superstructures are continuously reconstructed and relocated along the shaft, a process known as drift. Surprisingly, our results showed that most superstructures did not drift at all. Instead, we identified a novel mechanism for bone scaling, whereby each bone exhibits a specific and unique balance between proximal and distal growth rates, which accurately maintains the relative position of its superstructures. Moreover, we show mathematically that this mechanism minimizes the cumulative drift of all superstructures, thereby optimizing the scaling process. Our study reveals a general mechanism for the scaling of developing bones. More broadly, these findings suggest an evolutionary mechanism that facilitates variability in bone morphology by controlling the activity of individual epiphyseal plates.     

Effect of guard dogs on the behavior and reproduction of gazelles in cattle enclosures on the Golan Heights

Cattle on the Golan Heights are kept in enclosures and some of these enclosures have guard dogs. We studied the effect of such dogs on the behavior and breeding success of mountain gazelles Gazella gazella living within enclosures. We found that guard dogs have both direct and indirect effects on gazelles. Gazelles living in enclosures with dogs spent more time in vigilance behavior and running, and less time resting and walking, in comparison with gazelles in dog-free enclosures. In the absence of dogs, gazelle female herds in enclosures tended to stay closer to the cattle, but shunned away from them in the presence of the dogs, which, in turn, remained near the cattle. The percentage of fawns per female was higher in enclosures without dogs in comparison with those with dogs, but the difference was not significant. However, the largest of the enclosures with dogs, which had the largest number of gazelles, had only an average number of dogs in it. Hence, the gazelles in this enclosure were better able to avoid the dogs in comparison with those in smaller enclosures. Removing this enclosure from the overall calculation revealed that guard dogs have a significant negative effect on gazelle reproductive success. In two of the four enclosures with dogs no fawn still survived 6 months after birth, while in each of the four enclosures without dogs some fawns did survive to that age and beyond, suggesting that the dogs themselves may predate the fawns.     

Inhibitory effects of sub-optimal root zone temperature on leaf bioactive components, photosystem II (PS II) and minerals uptake in Trichosanthes cucumerina L. Cucurbitaceae

We hypothesized that sub-optimal root zone temperature (RZT) will cause a reduction in the bioactive components contents, adversely affect PS II and hinder uptake/partitioning of mineral elements in the “Light Green Variant” of the African snake tomato (Trichosanthes cucumerina L.). Three RZT temperatures (20, 25 and 30°C) were evaluated in a digitally controlled growth chamber. Results showed that for all the mineral nutrients analyzed (Ca, Mg, P, K, Fe and Mn), the amounts absorbed by the plant increase as RZT increases with each nutrient displaying different characteristics with respect to the quantity partitioned into root, stem and leaf at the different RZT. At sub-optimal RZT (20°C), significantly higher amounts of Ca and K were found in the root, whereas at normal RZT (25 and 30°C) higher amounts of Ca were recorded in the stem, and about 50% of the amounts in the stem were found in the leaves. For all the RZT, the amounts of Mg in the leaves were significantly higher than in the root and stem, while the amounts in the stems were also significantly higher than the amounts in the roots. At normal RZT (25 and 30°C) almost equal amounts of P were present in the root, stem and leaf. The amounts of phenolics, ascorbic acid, chlorophyll a and b and total chlorophyll increase as the RZT increases. Photosystem analyses showed that at 30°C the F _v/F _m (relative photochemical efficiency) was 0.76, while at 20 and 25°C the values were 0.35 and 0.60, respectively. The F _v/F _m value (0.35) obtained at 20°C confirmed the adverse effects of sub-optimal RZT on the photosystem II (PS II). Photosynthetic measurements showed that as the RZT increased, A (net photosynthetic efficiency), E (transpiration rate), C _i (intercellular carbon dioxide concentration) and g ₁ (stomata conductance) also increased. We postulate that the higher E and g ₁ at high RZT have a great physiological implication on plant performance, because transpiration cooling would be improved, especially during the summer; but the lost water must be complemented by adequate irrigation. The totality of the results confirm our hypothesis that sub-optimal RZT will cause a reduction in the bioactive components contents, adversely affect PS II and hinder uptake/partitioning of mineral elements in T. cucumerina.     

Vegetative performance,leaf water potential,and partitioning of minerals and soluble sugars: Traits for ranking the NaCl-tolerance of tomato genotypes?

This study addresses the physiological response of four tomato genotypes with distinct sensitivity to high NaCl concentrations, with the aim of identifying physiological traits to rank the genotypes’ sensitivity to salt stress. The central hypothesis was that tomato genotypes grown in saline environments show a characteristic salinity-triggered absorption and translocation of ions, leading to a distinct distribution pattern of Na, K, and soluble sugars. Experiments were conducted on two commercial cultivars: one assumed to be sensitive (Solanum lycopersicum L. F1 hybrid Harzfeuer) and one known to be tolerant (S. lycopersicum L. var. edkawi) to high salt concentrations. Furthermore, two wild salt-tolerant relatives (S. pennellii and S. lycopersicum var. cerasiforme) were selected. Based on our results regarding vegetative performance and partitioning of Na, K, glucose, fructose, and sucrose, it is possible to classify the genotype S. lycopersicum F1 hybrid Harzfeuer as moderately sensitive to salt stress and the genotypes S. lycopersicum var. edkawi, S. lycopersicum var. cerasiforme, and S. pennellii as moderately resistant to 210 mM NaCl. Calculations of the percentage of modification revealed non-specific genotype responses for the amount of sodium in roots and leaves, as well as the sucrose concentration and the osmotic potential of leaves. As shown, the salt-induced changes in potassium levels in leaves, and glucose concentration in roots might be used as additional traits to discriminate genotypes regarding their salt-sensitivity. These parameters might be useful when comparisons of fruit production or vegetative performance provide no conclusive indication e.g. due to the distinct growth habits of commercial cultivars selected for fruit productivity and native genotypes having a stronger vegetative development. However, additional studies should be conducted to evaluate a large number of genotypes differing in their NaCl tolerance. Furthermore, plant responses considering the dynamic source-sink relations due to fruit load needs to be considered.     

Pre symptomatic detection of wheat leaf rust in the susceptible cv Skalmeje and the resistant cv Esket by means of UV laser-induced fluorescence

In modern agriculture there is a great demand for a rapid and objective screening method for stress resistance, because so far, the resistance of new cultivars is tested in time- and money consuming field experiments. Based on fluorescence ratios, and lifetime of fluorophores measured by fluorescence spectroscopy, we have postulated that an early discrimination of susceptible and resistant wheat cultivars to the leaf rust pathogen Puccinia triticina can be accomplished. As representative for leaf rust resistant and leaf rust susceptible wheat genotypes the cultivars Esket and Skalmeje, respectively, were chosen. Plants were grown under controlled environment conditions and inoculated with the leaf rust pathogen at the second-leaf-stage by single-droplet application. Fluorescence measurements were carried out from two to four days after inoculation (dai) by using a compact fibre-optic fluorescence spectrometer with nanosecond time-resolution. Experimental results indicated that UV laser-induced spectral characteristics as well as determination of fluorescence lifetime are suited to detect leaf rust two dai. For this purpose several ratios and wavelength can be considered. In general, the tested cultivars showed distinct responses to the pathogen development. In this context the ratio F451/F687 measured three dai and mean lifetimes at 500 nm and 530 nm are suited to differentiate the resistant Esket from the susceptible Skalmeje genotypes.     

SIRT6 protects against pathological damage caused by diet‐induced obesity

The NAD+‐dependent SIRT6 deacetylase is a therapeutic candidate against the emerging metabolic syndrome epidemic. SIRT6, whose deficiency in mice results in premature aging phenotypes and metabolic defects, was implicated in a calorie restriction response that showed an opposite set of phenotypes from the metabolic syndrome. To explore the role of SIRT6 in metabolic stress, wild type and transgenic (TG) mice overexpressing SIRT6 were fed a high fat diet. In comparison to their wild‐type littermates, SIRT6 TG mice accumulated significantly less visceral fat, LDL‐cholesterol, and triglycerides. TG mice displayed enhanced glucose tolerance along with increased glucose‐stimulated insulin secretion. Gene expression analysis of adipose tissue revealed that the positive effect of SIRT6 overexpression is associated with down regulation of a selective set of peroxisome proliferator‐activated receptor‐responsive genes, and genes associated with lipid storage, such as angiopoietin‐like protein 4, adipocyte fatty acid‐binding protein, and diacylglycerol acyltransferase 1, which were suggested as potential targets for drugs to control metabolic syndrome. These results demonstrate a protective role for SIRT6 against the metabolic consequences of diet‐induced obesity and suggest a potentially beneficial effect of SIRT6 activation on age‐related metabolic diseases.     

Plasma homocysteine is regulated by phospholipid methylation

Mild hyperhomocysteinemia is an independent risk factor for cardiovascular disease. Homocysteine, a non-protein amino acid, is formed from S-adenosylhomocysteine and partially secreted into plasma. A potential source for homocysteine is methylation of the lipid phosphatidylethanolamine to phosphatidylcholine by phosphatidylethanolamine N-methyltransferase in the liver. We show that mice that lack phosphatidylethanolamine N-methyltransferase have plasma levels of homocysteine that are approximately 50% of those in wild-type mice. Hepatocytes isolated from methyltransferase-deficient mice secrete approximately 50% less homocysteine. Rat hepatoma cells transfected with phosphatidylethanolamine N-methyltransferase secrete more homocysteine than wild-type cells. Thus, phosphatidylethanolamine N-methyltransferase is an important source of plasma homocysteine and a potential therapeutic target for hyperhomocysteinemia.