Effect of salt on physiological responses of barley to iron deficiency.

Iron chlorosis is very common on alkaline soils such as calcareous ones, since iron availability is limited by high pH. Under these conditions of iron deficiency, graminaceous plant species induce special mechanisms for iron acquisition, involving enhanced release of iron chelators called phytosiderophores. On the other hand, it is known that most of salt soils have alkaline pH. So, plants growing on this kind of soils are often subjected simultaneously to salinity and iron deficiency. This work aimed at (i) studying the physiological responses of barley (Hordeum vulgare L.) to iron deficiency, and (ii) evaluating the effect of salt on the iron nutrition and the phytosiderophore release. For this purpose, seedlings of Hordeum vulgare L. were cultivated under controlled conditions, either in a complete nutrient solution with or without NaCl, or in an iron free nutrient solution containing or not NaCl. The plant morphological aspect, chlorophyll content of young leaves, iron status, biomass production, and phytosiderophore release by roots were assessed. Plants subjected to Fe deficiency exhibited a severe chlorosis, accompanied by a significant biomass reduction. These plants developed more lateral roots than the control with a highly stimulated phytosiderophore release. However, the latter was greatly diminished when iron deficiency was associated to salinity. A depressive effect of salt on iron acquisition in plants subjected only to salt stress which was also observed and further confirmed by the important decrease of efficiency in iron acquisition. These results suggest that salinity may reduce capacity of plants to acquire iron from alkaline soils by inhibiting phytosiderophore release.     

Expression of enzymes involved in estrogen metabolism in human prostate.

There is evidence that estrogens can directly modulate human prostate cell activity. It has also been shown that cultured human prostate cancer LNCaP can synthesize the active estrogen estradiol (E2). To elucidate the metabolism of estrogens in the human prostate, we have studied the expression of enzymes involved in the formation and inactivation of estrogens at the cellular level. 17beta-Hydroxysteroid dehydrogenase (17beta-HSD) types 1, 2, 4, 7, and 12, as well as aromatase mRNA and protein expressions, were studied in benign prostatic hyperplasia (BPH) specimens using in situ hybridization and immunohistochemistry. For 17beta-HSD type 4, only in situ hybridization studies were performed. Identical results were obtained with in situ hybridization and immunohistochemistry. All the enzymes studied were shown to be expressed in both epithelial and stromal cells, with the exception of 17beta-HSD types 4 and 7, which were detected only in the epithelial cells. On the basis of our previous results, showing that 3beta-HSD and 17beta-HSD type 5 are expressed in human prostate, and of the present data, it can be concluded that the human prostate expresses all the enzymes involved in the conversion of circulating dehydroepiandrosterone (DHEA) to E2. The local biosynthesis of E2 might be involved in the development and/or progression of prostate pathology such as BPH and prostate cancer through modulation of estrogen receptors, which are also expressed in epithelial and stromal cells.     

A mosquito predator survey in Townsville, Australia, and an assessment of Diplonychus sp. and Anisops sp. predatorial capacity against Culex annulirostris mosquito immatures.

A twelve-month survey for mosquito predators was conducted in Townsville, Queensland, Australia, which is located in the arid tropics. The survey revealed the presence of five predaceous insects but only Anisops sp. (backswimmers) and Diplonychus sp. were common. Predatorial capacity and factors influencing this capacity were then assessed for adult Anisops sp. and adult and nymph stages of Diplonychus sp. against Culex annulirostris mosquito immatures under laboratory conditions. Predatorial capacity bioassays showed that adult Diplonychus sp. preyed upon both larval and pupal stages of Cx. annulirostris quite successfully. Nymphs of Diplonychus sp. proved to be more successful with smaller prey immatures, and Anisops sp adults did not prey successfully on any prey pupae. Increasing the foraging area and introducing aquatic vegetation significantly reduced the predatorial capacity of Diplonychus sp. nymphs, while only vegetation and not foraging area had a significant effect on adult Diplonychus sp. predation capacity. Overall, adult Diplonychus sp. proved to be a more efficient predator than Anisops sp., and field trials are now recommended to further assess the potential of Diplonychus sp. as a biocontrol agent.     

Fruit and seed development inCucurbita foetidissima

Cucurbita foetidissimaHBK., a wild perennial xerophytic species indigenous to semi-arid lands of North America is reproduced primarily vegetatively, but is a prolific producer of fruit and seed. The seed contains an acceptable edible oil. Fruit development reaches its maximum weight 10 days after pollination, but seed development continues until 32 to 34 days after pollination. Physiological development of the seed as measured by germination is not coincidental with physical development.     

Demonstration of phosphorylase activity in the rat brain

Summary The phosphorylase reaction in rat brain is strong, but for its correct evaluation in pathological states certain precautions are needed. Control material from animals of the same age should be used identically and simultaneously with the pathological, preferably freezing blocks from each on the same holder. Several sections should be cut and then the holder rotated through 180° and more sections cut, thus avoiding changes in section thickness which can drastically influence the color reactions, i.e., apparent phosphorylase activity. The time the animal is killed until its brain is frozen should be less than 5 min, preferably 11/2 to 3 min, to limit postmortem changes in the enzyme.Preparing the stock incubating medium and storing it at 4°C does not affect the potency of the medium; this procedure is convenient and eliminates more variables.Small amounts of medium can be placed between two slides set at right angles to each other. The height of the chamber, equal to the thickness of a slide, is uniform.Prefixation of the cryostat sections in cold acetone (4°C) for 5 min can be useful for obtaining sharper enzyme localization.AMP is the nucleotide of choice for stimulating full phosphorylase reaction. The inclusion of glycogen in the incubating medium is also necessary.The optimal incubation time for phosphorylase + branching enzyme is about 1/2 hr for 16 sections. For phosphorylase alone (active or total) it is about 2 hr. Dehydrating, clearing, and mounting in iodine-containing solutions is not recommended nor is it necessary. The best preservation of original colors, which is important for the correct interpretation of the results, is accomplished by sealing the preparations mounted in iodine-glycerin with paraffin.     

Comparison of weight-length relationships and relative growth between intertidal and offshore populations of <Emphasis Type="Italic">Hexaplex trunculus</Emphasis> (Gastropoda: Muricidae) from the Gulf of Gabès (southern Tunisia)

The present study reports weight-length (W-L) relationships and discusses the relative growth of the banded murex (Hexaplex trunculus) from intertidal and offshore areas of the Gulf of Gabès (southern Tunisia). Overall, 9634 H. trunculus were sampled (6608 from intertidal and 3026 from offshore), with both populations comprising broad ranges in shell length (intertidal: 13.6–78.5 mm; offshore: 22.9–91.1 mm) and total weight (intertidal: 0.2–63.8 g; offshore: 0.6–92.5 g). In both populations, W-L relationships were highly significant and the morphometric parameters were highly correlated (intertidal: r?=?0.967; offshore: r?=?0.973). Relative growth was significantly different between populations, with intertidal H. trunculus displaying a negative allometry (b?=?2.962) and offshore H. trunculus exhibiting isometric growth (b?=?3.013). Factors influencing total weight (soft-body weight and shell weight) and potentially responsible for differences in W-L relationships and relative growth between populations were discussed. In addition, a useful comparative analysis for fisheries biology, assessment and management purposes was performed with analogous information from other populations of H. trunculus from the Mediterranean Sea and the Atlantic Ocean.