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1.
An account is given of the elysiid sacoglossans collected ondiving expeditions to the eastern Mediterranean shores of Yugoslaviaand Greece during the period 1978–1986, supplemented bymaterial collected around Naples and some preserved specimensfrom other Mediterranean localities. In all, 6 species of Elysiaand 1 of Bosellia were investigated, including one new to science,E. gordanae from the Yugoslav Istrian Peninsula. The enigmaticElysia translucens Pruvot-Fol, 1957 was found in the easternbasin for the first time. The presence of the Bermudan, CanaryIslands and Jamaican E. flava Verrill, 1901 was confirmed inthe Greek Ionian and Aegean Seas, as well as in the Gulf ofCorinth. The geographical ranges of the other species were extendedby these collections from the eastern basin. The 7 elysiid specieswere illustrated from life and the radulae compared; great differencesin the size, shape and denticulation of the teeth of the differentspecies were evident (Received 8 May 1987;  相似文献   

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All tillers of timothy ( Phleum pratense ) growing in sand culture were labelled at weekly intervals. At each of eighteen dates between June and December a sample of plants was harvested, and dry weight and leaf area were determined for each group of tillers.
Tiller production was continuous throughout the experiment. Only those tillers which appeared before the end of July were able to form inflorescences, but among them the proportion of tillers with ears decreased with increasing lateness of origin.
Dry weight per plant increased rapidly for the first 14 weeks, and then did not change significantly until the end of the experiment. The flowering tillers lost dry weight after seed maturation; vegetative tillers, although smaller in size, continued to increase in number and weight. Dry weight per inflorescences was greatest in the main stem and decreased in subsequent tillers.
Leaf area per plant rose to a maximum soon after ear emergence and then declined, largely because the loss in leaf surface sustained by the flowering tillers was not offset by a corresponding increase in the vegetative tillers. Leaf area ratio decreased at first rapidly but later more gradually, while net assimilation rate was relatively high until maximum leaf area was almost attained, but then fell continuously to negligible values by October. Relative growth rate decreased throughout the experiment.
Initially the growth of the plant was largely determined by the flowering tillers in which, in close resemblance to the cereal plant, leaf area ratio and relative growth rate declined continuously. Tillers which did not flower were successively smaller in size and, because of their later origin, were exposed to less favourable environmental conditions by the time they had increased sufficiently in number to affect the growth of the plant.  相似文献   

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GROWTH AND NUTRITION OF TIMOTHY (PHLEUM PRATENSE)   总被引:3,自引:0,他引:3  
Individual tillers of timothy ( Phleum pratense ) growing from seed in pots were labelled and their life history studied over a period of two years.
The leaf axil position of the first-produced tiller depended on its time of origin. A minimum of five leaves on the parent axis was necessary before its appearance, and no tiller emerged from the axil of any of the three terminal leaves of a shoot.
Ear-bearing capacity was high in early-formed tillers, but decreased progressively with later dates of origin despite favourable day length; all tillers arising after the end of July failed to produce inflorescences. A greater proportion of tillers on the main stem formed ears than secondary tillers of the same age. Time of ear emergence varied only within a few days for all tillers arising before the end of April. The number of leaves formed up to ear emergence varied linearly with date of origin and tiller position, the lowest recorded number being six.
Dry weight and length of inflorescence as well as seed yield per tiller varied linearly with the date of origin of tillers. Primary tillers generally had longer and heavier inflorescences and produced more seed per stem than secondary tillers of the same age.
Tillers arising at all times were found to have a limited span of life, not normally exceeding just over a year. The mean age of ear-bearing tillers varied linearly with their date of origin. Death-rates of all tillers generally increased with their age. Relative death-rates of fertile and vegetative tillers rose rapidly in the autumn but decreased during winter and early spring. Vegetative tillers which elongated in the year of formation survived for a shorter time than equivalent tillers in which stem elongation was delayed until the following year.
The perennial habit of grasses is discussed in relation to tiller survival. Successive new formation and death of tillers keep the plant in a condition of continuous dynamic change.  相似文献   

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An account is given of the ceratiform sacoglossans collectedon diving expeditions to the Mediterranean shores of Yugoslaviaand Greece during the period 1978–86. Six species aredescribed, two of which, Cyerce graeca and Hermaea (Placida)saronica, are new to science; four of the six represent additionsor new records for the eastern Mediterranean (Received 20 July 1987;  相似文献   

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《Endocrine practice》2018,24(5):468-472
Objective: Iodine is a required nutrient for thyroid function. The mountainous terrain in the Republic of Artsakh (Nagorno Karabakh) in the south Caucasus suggests that it is likely to be endogenously deficient in iodine. The region is heavily dependent on neighboring Armenia for food imports including iodized salt. Since 2005, iodine is a government-sanctioned compulsory supplemental ingredient in salt in Armenia. However, there has never been a study of iodine nutrition in Artsakh. We sought to determine the level of iodine nutrition in Artsakh and the iodine content of table salt in the region.Methods: Using a cross-sectional modified cluster model, we measured urine and salt iodine concentrations from a representative sample of children living in Artsakh. From 30 schools throughout the territory, we obtained 772 urine samples from children aged 8 to 10, and 323 samples of table salt. Repeat urine samples from 18.6% of participants were obtained.Results: The median adjusted urinary iodine content was 203 μg/L (mean 206 μg/L, 95% confidence interval 202–210), within the range indicating sufficient iodine nutrition. There were small but statistically significant differences between the 8 administrative regions; however, there were no differences between individual sites. We found that 97.2% of table salt samples tested had iodine concentrations within the standard of 25 to 55 mg/kg.Conclusion: Among school-age children in Artsakh, iodine nutrition is adequate, and the salt is appropriately iodized. These results illustrate the remarkable success of the Armenian salt iodization program in providing sufficient but not excessive iodine to the mountainous territory of Artsakh.Abbreviation: UIC = urinary iodine concentration  相似文献   

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Data on egg size, capsule size, development type, and the presence and nature of albumen are summarized for 32 species of Ascoglossa, including new data on 23 species from Florida and the Caribbean. Lower limits of egg sizes for Ascoglossa with lecithotrophic and capsular development were substantially lower than limits reported for other opisthobranchs, probably because of the use of albumen as nutrient reserves in species with extended development. Capsule size is a more accurate predictor of development type than egg size. The use of albumen as a nutrient resource is associated with a relatively high plasticity of development.  相似文献   

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Three clones of marine Synechococcus (WH6501, WH7803, and WH8018) were grown through at least three transfers, at 6-day intervals, in synthetic medium with total iron concentrations from 10?9 to 10?6 M. After 6 days of exponential growth, these cultures were harvested, and the cell density and protein and pigment concentrations were measured. Aliquots of the culture were assayed for their carbon fixation rates at two light intensities. Cell density and protein concentration increased by up to 7.8 times over a range of iron from the lowest (10?9 M) to the highest concentrations (10?6 M). The concentration of chlorophyll-a and phycobiliproteins showed a wider range of response, increasing by up to 48 times. The carbon fixation rate (per mL of culture) also increased approximately 40 times over the total range of iron concentration. The ranges of these biochemical and physiological responses were much lower than the range of total available iron, which was 1000-fold, and the range of total cellular iron, which was estimated to be about 160-fold. This “less-than-linear” relationship indicates that the cells are adapting to make more efficient use of iron under limiting conditions. Our results demonstrate characteristics of iron-limited Synechococcus that may be important in understanding the relationships between primary productivity and iron availability in the oceans.  相似文献   

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The Elysiidae is the largest family of Sacoglossa (=Ascoglossa)(Mollusca, Opisthobranchia). The Indo-Pacific fauna containsabout 65 species presently referred to the genus Elysia. Almostnothing is known about the internal anatomy of these animals.In the present study the internal anatomy, particularly thepharyngeal musculature, morphology of radularteeth, and reproductivesystems, of 12 Indo-Pacific elysiids is investigated. Also,the internal anatomy of the Mediterranean type species of thegenera Elysia and Thuridilla is described. On this basis, thevalidity of the genera Elysia, Thuridilla, Elysiella and Pattyclaya,is confirmed. Also, the genus Placobranchus is transferred tothe Elysiidae. phylogenetically important characters are identifiedand phylogenetic relationships within the family are discussed. (Received 10 April 1991; accepted 28 December 1991)  相似文献   

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THE NUTRITION OF BRUCELLAE   总被引:1,自引:0,他引:1       下载免费PDF全文
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In 1935, nutritional work on lettuce was started by the author. The investigations were divided into three sections: sand-culture experiments, soil-culture experiments, and field-fertilizer trials. The results of the sand-culture work have been published (Woodman, 1936, 1939 a, b, c, d , 1940 a, b ); the present paper deals with the results obtained so far from soil cultures and field trials.  相似文献   

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