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61.
62.
This study examined the microscopic structure of the small intestine and digestion and absorption in the hybrid tilapia, Oreochromis niloticus×Oreochromis aureus. The small intestine was lined on the luminal face with villi, which were narrower and more dense in the proximal small intestine and became wider and sparser distally. The columnar epithelial cells lining the villi were predominantly enterocytes containing a brush border, interspersed with mucus containing goblet cells approximately every 4–6 cells. These mucus‐secreting cells contained both acid and basic mucins and increased in density in the distal and the terminal sections of the intestine. Proliferation of enterocytes was observed in the intervillus areas and lower third of the villus. Fish were fed diets of either fish meal or fish meal–wheat to which chromic oxide had been added as a non‐absorbed reference standard. Activity of the pancreatic enzymes, lipase, trypsin and amylase were determined along the small intestine relative to the non‐absorbed marker. Activity of these pancreatic enzymes was maximal in the proximal segments and decreased distally. Changes in the activity patterns of trypsin and amylase were observed with the different diets in the proximal small intestine. Net secretion of both N and fatty acids was found in the hepatic loop and absorption commenced distally decreasing in rate with distance from the pylorus. The pattern of N absorption in the proximal small intestine changed with the different diets. The structure and function of the small intestine of the tilapian omnivore thus are generally similar to mammals and digestion and absorption adapt with diet. 相似文献
63.
The tomato mutant flacca wilts rapidly under water deficit because its stomata resist closure. Application of abscisic acid to intact mutant plants changes their morphology toward the phenotype of the control normal variety, Rheinlands Ruhm. The treated mutant plants do not show wilting symptoms, and the resistance to closure of their stomata decreases with hormone treatment. 相似文献
64.
Mezey E Nagy A Szalayova I Key S Bratincsak A Baffi J Shahar T 《Science (New York, N.Y.)》2003,299(5610):1184; author reply 1184
65.
Arnon TI Xu Y Lo C Pham T An J Coughlin S Dorn GW Cyster JG 《Science (New York, N.Y.)》2011,333(6051):1898-1903
Lymphocytes egress from lymphoid organs in response to sphingosine-1-phosphate (S1P); minutes later they migrate from blood into tissue against the S1P gradient. The mechanisms facilitating cell movement against the gradient have not been defined. Here, we show that heterotrimeric guanine nucleotide-binding protein-coupled receptor kinase-2 (GRK2) functions in down-regulation of S1P receptor-1 (S1PR1) on blood-exposed lymphocytes. T and B cell movement from blood into lymph nodes is reduced in the absence of GRK2 but is restored in S1P-deficient mice. In the spleen, B cell movement between the blood-rich marginal zone and follicles is disrupted by GRK2 deficiency and by mutation of an S1PR1 desensitization motif. Moreover, delivery of systemic antigen into follicles is impaired. Thus, GRK2-dependent S1PR1 desensitization allows lymphocytes to escape circulatory fluids and migrate into lymphoid tissues. 相似文献
66.
Shoshan Tal Bechar Avital Cohen Yuval Sadowsky Avraham Berman Sigal 《Precision Agriculture》2022,23(2):514-537
Precision Agriculture - Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automation can significantly reduce labor and improve efficiency. An image processing... 相似文献
67.
Innis MA Holland MJ McCabe PC Cole GE Wittman VP Tal R Watt KW Gelfand DH Holland JP Meade JH 《Science (New York, N.Y.)》1985,228(4695):21-26
A strain of Saccharomyces cerevisiae capable of simultaneous hydrolysis and fermentation of highly polymerized starch oligosaccharides was constructed. The Aspergillus awamori glucoamylase enzyme, form GAI, was expressed in Saccharomyces cerevisiae by means of the promoter and termination regions from a yeast enolase gene. Yeast transformed with plasmids containing an intron-free recombinant glucoamylase gene efficiently secreted glucoamylase into the medium, permitting growth of the transformants on starch as the sole carbon source. The natural leader sequence of the precursor of glucoamylase (preglucoamylase) was processed correctly by yeast, and the secreted enzyme was glycosylated through both N- and O-linkages at levels comparable to the native Aspergillus enzyme. The data provide evidence for the utility of yeast as an organism for the production, glycosylation, and secretion of heterologous proteins. 相似文献
68.
Summary The cultivated potatoSolanum tuberosum cvs Alpha and Russet Burbank and the wild speciesS. kurzianum were compared with respect to salt tolerance. Plants of the wild species were found to be more salt tolerant than those of
the cultivated species since their growth was less impaired by the salinity, although they accumulated more sodium and less
potassium ions in the shoot. Unlike the whole plant, callus derived from the wild plants was not more tolerant than that from
the cultivated species. Differences in the responses to salinity between cultivated and wild plants, and between the whole
plants and calli derived from them are discussed. Based on these differences and the similarity of the physiological responses
to salt stress betweenS. kurzianum and the wild salt-tolerant relatives of tomato, the former is suggested as a potential source of genes for increasing the
salt tolerance of potato. 相似文献
69.
Yossi Tal Ari Ayalon Agnesa Sharaev Zoya Kazir Vera Brekhman Tamar Lotan 《Marine drugs》2014,12(2):734-745
Transdermal delivery is an attractive option for drug delivery. Nevertheless, the skin is a tough barrier and only a limited number of drugs can be delivered through it. The most difficult to deliver are hydrophilic drugs. The stinging mechanism of the cnidarians is a sophisticated injection system consisting of microcapsular nematocysts, which utilize built-in high osmotic pressures to inject a submicron tubule that penetrates and delivers their contents to the prey. Here we show, for the first time, that the nematocysts of the starlet sea anemone Nematostella vectensis can be isolated and incorporated into a topical formulation for continuous drug delivery. We demonstrate quantitative delivery of nicotinamide and lidocaine hydrochloride as a function of microcapsular dose or drug exposure. We also show how the released submicron tubules can be exploited as a skin penetration enhancer prior to and independently of drug application. The microcapsules are non-irritant and may offer an attractive alternative for hydrophilic transdermal drug delivery. 相似文献
70.
During the past 60 years, afforestation has transformed Israel’s landscape, with forests planted or planned on 10% of the
country’s land, much of it with less than 300 mm of annual precipitation. After early efforts to establish a successful commercial
timber industry failed, recreation and ecosystem services came to dominate forestry policy objectives. Given Israel’s status
as a ‘developing country’ under the Kyoto Protocol, forests’ economic potential through carbon sequestration has been explored,
but has not yet proven to be compelling. Several considerations cooled initial enthusiasm for seeking international carbon
credits through afforestation. These include administrative obstacles associated with international accreditation, limited
potential economic profitability, and ethical considerations. Rather, a voluntary offsetting program was adopted, allowing donors to plant trees in Israel, that balance individual carbon
emissions. Afforestation in drylands exhibit meaningful potential to counteract chronic carbon loss due to land degradation.
As trees planted in Israel’s semi-arid regions exhibit surprisingly high carbon sequestration properties that are comparable
to forests in temperate Europe, the potential for offsetting may become a growing factor in local forestry policy once Israel
begins to regulate CO2 emissions. 相似文献