Spelling suggestions: "subject:"zinc - aphysiological effect"" "subject:"zinc - byphysiological effect""
11 |
The effect of zinc deficiency on the growth promoting actions of growth hormone and insulin-like growth factor-I /Cha, Ming Chuan, 1955- January 1994 (has links)
The effect of zinc deficiency on the growth promoting effect of circulating IGF-I and the direct growth effect of GH on long bone growth were investigated. Food intake was decreased by lack of zinc in the diet. Tissue zinc content and plasma alkaline phosphatase activity were reduced by zinc deficiency. Systemic administration of human IGF-I increased the body weight, tail length and tibia epiphyseal cartilage width of control animals. This somatogenic action was impaired by zinc deficiency, as evidenced by continued weight loss, no increase in tail length and decreased tibial epiphyseal cartilage width of zinc deficient animals. Unilateral arterial infusion of GH increased the tibial epiphyseal width of the treated limb but not of the non-treated limb in control rats. However, no difference was found between the infused and the non-infused limb of zinc deficient animals, suggesting the occurrence of GH resistance on long bone growth in zinc deficiency. We conclude that zinc deficiency inhibits the growth promoting action of circulating IGF-I and the direct growth effect of GH on long bone growth.
|
12 |
Effect of low dietary zinc supply during pregnancy and lactation on the sow and the neonatal pigletKalinowski, Juan. January 1985 (has links)
Experiments were conducted with sows and littermate-gilts to investigate the effect of dietary zinc (Zn) restriction during either part or most of the pregnancy and lactation on dams and their offspring. / Reduced dietary Zn (13 ppm) during the last 4 wk of pregnancy and first 2 wk of lactation presented no serious consequences to the dam or offspring. Reduction of dietary Zn throughout pregnancy and lactation (10 ppm) caused overt signs of Zn deficiency in one-half of the gilts, however, their offspring exhibited no obvious abnormalities. Zinc restriction did not affect feed consumption but depressed plasma and urinary Zn and plasma alkaline phosphatase activity (APA). The use of the balance technique and radiotracers revealed that gilts deficient in Zn initiated protective mechanisms such as, increased Zn absorption reduced endogenous Zn excretion, prolongation of the biological half life of Zn; all these responses affected higher efficiency of Zn utilization. / Despite the protective mechanisms, gilts depleted in Zn exhibited prolonged stressful parturition and a high incidence of intrapartum and neonatal mortality than control gilts. Piglets from gilts depleted in Zn showed depressed birth weight, reduced concentrations of plasma Zn, Cu and ammonia and low APA and hematocrit, increased plasma concentrations of glucose and lactate, reduced content of Zn in liver, heart, lung, skin, bone and carcass and higher concentrations of Cu and Mn in various tissues compared to controls. Zinc depletion did not change the Zn content of colostrum but did change it in milk. Content of Cu, Fe, and Mn was effected in colostrum and milk. Weight of piglets was lower at one wk but not at two wk of age. Two-week old piglets exhibited lower Zn and higher Cu concentrations in plasma; reduced Zn and increased Cu and Mn concentrations in liver and bone and changes in Cu and Mn in other tissues. At the end of lactation, gilts depleted in Zn exhibited low level of Zn and APA in plasma; reduced Zn content in liver, spleen, heart, small intestine; increased Cu content in liver and small intestine; increased Zn and Mn content in brain. / Although gilts depleted in Zn exhibited a highly efficient handling of Zn via homeostatic mechanisms, the reduced amount of corporal exchangeable Zn in these gilts caused biochemical changes affecting the performance of the dam and the offspring. (Abstract shortened with permission of author.)
|
13 |
Uptake and retention of zinc-65 from seawater by Euphausia pacifica HansenFowler, Scott Wellington 13 May 1966 (has links)
Graduation date: 1966
|
14 |
Effect of low dietary zinc supply during pregnancy and lactation on the sow and the neonatal pigletKalinowski, Juan. January 1985 (has links)
No description available.
|
15 |
The effect of zinc supplementation on cadmium, zinc and copper in liver, muscle, hair, blood and feces of calves fed cadmium.Lamphere, David Norval January 1981 (has links)
No description available.
|
16 |
The interaction of dietary protein and zinc deficiencies with Heligmosomoides polygyrus infection in mice /Boulay, Marjolaine January 1994 (has links)
No description available.
|
17 |
The effect of zinc deficiency on the growth promoting actions of growth hormone and insulin-like growth factor-I /Cha, Ming Chuan, 1955- January 1994 (has links)
No description available.
|
18 |
Determination of mechanism of zinc resistance in Chironomus riparius: a physiological/energetic approachMiller, Mark Perry 11 June 2009 (has links)
The objective of this project was to investigate two mechanisms that are commonly thought to be responsible for heavy metal resistance in aquatic invertebrates. Data were generated based on comparisons of growth and respiration experiments using instar III and IV Chironomus riparius under the influence of 0.0, 62.5, 125, 250, and 500 ppb zinc. Main comparisons were made between larvae that were cultured in clean water conditions and larvae from cultures that had been exposed to 10 ppb zinc for over a year and a half. Instar III larvae from clean water cultures showed significant reductions in growth and respiration rates when exposed to zinc concentrations of 62.5 ppb and greater; growth and respiration rates were significantly reduced in instar IV larvae at 125 and 62.5 ppb, respectively. Instar IV larvae from zinc cultures demonstrated increased tolerance to the metal while instar III larvae displayed no additional tolerance. To determine if the resistance was an acclimation or population adaptation phenomenon, additional growth and respiration experiments were conducted with F2 progeny of adults from zinc cultures that were reared in clean water. Results suggest that both acclimation and adaptation may be responsible for the increased tolerance to the metal. When growth and respiration data were converted to a caloric basis (calories respired per day and calories allocated as growth per day), non-tolerant individuals decreased the amount of energy assimilated per day and increased the proportion of energy respired vs. energy allocated to growth with increasing zinc concentration. Resistant individuals, as a result of changes in toxicological trends, demonstrated less dramatic versions of the previously described trends. / Master of Science
|
19 |
Histological change in the hepatopancreas of terrestrial isopods as potential biomarker of cadmium and zinc exposureOdendaal, James Philander 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Metals occur naturally in the environment but since the industrial revolution the amounts
ofbioavailable metals in the environment have increased significantly. There are various
anthropogenic sources of metals in the environment. In recent years there has been an
increasing interest in the use of biomarkers in terrestrial invertebrates for the assessment
of the potential adverse effects of chemicals in soil ecosystems. Terrestrial isopods are
one of the groups that play an important role in the decomposition process as fragmentors
of dead plant material in soil ecosystems. They are also known to accumulate
contaminants in their bodies, especially in the hepatopancreas. Cadmium has no known
biological function and is deposited in the environment through a variety of sources.
Zinc on the other hand is one of the essential metals and play an important role in the
normal metabolism of animals. Zinc too, is deposited in the environment through a
variety of anthropogenic sources. The aim of this study was to undertake an
experimental and field evaluation of the role cellular change in the hepatopancreas of
terrestrial isopods can play in conjunction with other sublethal responses to contribute to
the assessment of the impact of cadmium and zinc in terrestrial ecosystems.
Porcel/io laevis was used as test species in the laboratory experiments in this
study, to conduct sublethal toxicity tests. Cadmium- and zinc sulphate were used as the
contaminants, applied separately and as mixtures. The isopods were weighed before the
beginning of the exposures and every week throughout the exposure period of six weeks.
At the end of the exposure period they were dissected to remove the hepatopancreas. The
zinc and cadmium content of the hepatopancreases and rest of the bodies of the isopods were determined by atomic absorption spectrophotometry. Hepatopancreas samples were
also prepared for histological analysis, and measurements of the Percentage Cellular Area
(PCA) were made using image analysis. Specimens of Porcellionides pruinosus were
collected from contaminated- and uncontaminated field sites. Hepatopancreas- and rest
of the body samples of P. pruinosus were also analysed for cadmium and zinc.
Histological sections of the hepatopancreas were similarly prepared and analysed, as in
the laboratory experiments.
Exposure to cadmium- and zinc sulphate affected the mass of P. laevis negatively
in the single metal exposures. However, these two metals "neutralised" each other's
effects in the mixture toxicity exposures, pointing towards an antagonistic interaction.
Administered cadmium- and zinc sulphate resulted in the accumulation of cadmium and
zinc in the isopods, especially in the hepatopancreas. In the mixture toxicity experiments
cadmium and zinc influenced the accumulation of each other. Cadmium- and zinc
sulphate, whether administered separately or as mixtures, changed the structure of the
hepatopancreas and this was quantitatively shown through PCA measurements. PCA of
the hepatopancreas of terrestrial isopods was shown to be a good general biomarker of
exposure and effects for cadmium as well as for zinc. It is suggested that PCA could
serve as a general biomarker to predict possible impairment of growth or mass change of
isopods exposed to cadmium and zinc mixtures. The findings of the field survey also
suggest that PCA may be suitable to be used as a general biomarker to measure metal
induced stress in woodlice from contaminated field sites. / AFRIKAANSE OPSOMMING: Metale kom natuurlik voor in die omgewing, maar sedert die industriële revolusie het die
hoeveelheid bio-beskikbare metale in die omgewing betekenisvol toegeneem. Daar is
verskeie antropogeniese bronne van metale in die omgewing. Die afgelope paar jaar was
daar toenemende belangstelling in die gebruik van biomerkers by terrestriële invertebrate
vir die assessering van potensiële negatiewe effekte van chemiese stowwe in
grondekosisteme. Terrestriële Isopoda is een van die groepe wat 'n belangrike rol speel
III die ontbindingsproses as fragmenteerders van dooie plantmateriaal III
grondekosisteme. Hulle akkumuleer ook kontaminante in hul liggame, veral in die
hepatopankreas. Kadmium het geen biologiese funksie nie, en word vrygestel in die
omgewing deur verskeie bronne. Sink, aan die ander kant, is een van die essensiële
metale en speel 'n belangrike rol in die metabolisme van diere. Sink word ook in die
omgewing vrygestel deur 'n verskeidenheid antropogeniese bronne. Die doel van die
studie was om deur eksperimentele en veldondersoek die rol van sellulêre veranderinge in
die hepatopankreas van terrestriële Isopoda in samehang met ander subietale response te
evalueer om by te dra tot die assessering van die impak van kadmium en sink op
terrestriële ekosisteme.
Porcellio laevis is as toets-spesie in die laboratorium eksperimente gebruik om
subietale toksisiteitstoetse mee uit te voer. Kadmium- en sinksulfaat is as kontaminante
gebruik, en is apart en gemeng toegedien. Die houtluise is geweeg voor die begin van die
blootstellings en elke week deur die loop van die blootstellingsperiode van ses weke.
Aan die einde van die blootstellingsperiode is hulle gedissekteer om die hepatopankreas te verwyder. Die sink en kadmium inhoude van die hepatopankreas en res van die
liggame van die houtluise is bepaal met behulp van atoomabsorpsiespektrofotometrie.
Monsters van die hepatopankreas is ook voorberei vir histologiese analise, en metings
van die Persentasie Sellulêre Oppervlak (PSO) is gedoen met behulp van beeldanalise.
Eksemplare van Porcellionides pruinosus is versamel van 'n gekontamineerde- en 'n
ongekontamineerde gebied. Monster van die hepatopankreas en res van die liggaam van
P. pruinosus is ook geanaliseer vir kadmium en sink. Histologiese sneë van die
hepatopankreas was ook voorberei en geanaliseer, soos in die laboratorium eksperimente.
Blootstelling aan kadmium- en sinksulfaat het die massa van P. laevis negatief
beïnvloed in die enkelmetaal-eksperimente. Hierdie twee metale het egter mekaar se
effekte in die mengseltoksisiteitstoetse "geneutraliseer". Dit dui op 'n antagonistiese
interaksie. Toegediende kadmium- en sinksulfaat het gelei tot die akkumulasie van
kadmium en sink in the houtluise, veral in die hepatopankreas. In die
mengseltoksisiteitstoetse het kadmium en sink mekaar se akkumulasie beïnvloed.
Kadmium- en sinksulfaat, apart of as mengsels toegedien, het die struktuur van die
hepatopankreas verander, en dit is kwantitatief aangetoon deur die PSO metings. PSO
van die hepatopankreas van houtluise is 'n bruikbare algemene biomerker van
blootstelling en effek vir kadmium en sink. Dit word voorgestel dat PSO kan dien as 'n
algemene biomerker om negatiewe effekte op die groei of massaverandering van
houtluise te voorspel wat aan kadmium en sink mengsels blootgestel word. Die
bevindinge van die veldondersoek dui daarop dat PSO gepas mag wees om gebruik te
word as 'n algemene biomerker om metaal-geïnduseerde stres by houtluise vanaf 'n
gekontamineerde gebied te meet.
|
20 |
Responses of chickpea (Cicer arietinum L.) to zinc supply and water deficitsKhan, Habib Ur Rahman. January 1998 (has links) (PDF)
Bibliography: leaves 201-228. Widespread deficiencies of mineral nutrients in soils along with limited moisture supply are considered major environmental stresses leading to yield losses in chickpea. This study was conducted to determine the zinc requirement of chickpea and the effect on plant water relations. Critical zinc concentration was estimated. It was found that high and low moisture regimes had no effect on critical zinc concentration and that the value remained almost the same in all chickpea genotypes. Sensitivity of 28 chickpea genotypes were evaluated at two zinc levels. Field studies on zinc fertilization in both Australia and Pakistan showed that the application of zinc increased grain yield in all chickpea genotypes. It was found that plants grown under zinc deficiency could not exploit available soil moisture and water use and water use efficiency was reduced, and concluded that high zinc availability may enhance the ability of plants to endure periods of drought by promoting osmotic adjustment.
|
Page generated in 0.0777 seconds