Effects of plant growth-promoting rhizobacteria Klebsiella michiganensis TS8 and Lelliottia jeotgali MR2 on the growth and cadmium uptake of Arabidopsis thaliana under cadmium stress / 生物工程学报

In this study, the effects of two plant growth-promoting bacteria Klebsiella michiganensis TS8 and Lelliottia Jeotgali MR2 on the growth and cadmium (Cd) uptake of Arabidopsis thaliana under Cd stress were explored. A wild-type Arabidopsis thaliana was selected as the experimental plant and was planted at different Cd concentrations. MR2 and TS8 bacterial suspensions were sprayed onto the rhizospheric soil during the planting process. The initial Cd concentration of the bought soil was 14.17 mg/kg, which was used as the pot soil of the low-concentration Cd treatment group (LC). The concentration of soil Cd at high-concentration Cd treatment group (HC) were 200 mg/kg higher than that at LC group. Compared with the control group, MR2 suspension significantly promoted the growth of A. thaliana at both low and high concentrations, while TS8 strain and MR2_TS8 mixture only exhibited growth-promoting effect at high concentration. However, it was noteworthy that, TS8 suspension significantly reduced the Cd content in the underground parts of A. thaliana (60% and 59%), and significantly improved the Cd content in the aboveground parts of A. thaliana (234% and 35%) at both low and high concentrations. In addition, at low concentration, both single strain and mixed strains significantly improved the transformation from reducible Cd to acid-extractable Cd in soil, promoted Cd intake, and thereby reduced the total Cd content in soil. Therefore, the rational application of plant growth-promoting bacteria may improve crop yield and remediate Cd contamination in soil.

[Study on hematology and serum biochemistry of common carp [Cyprinus carpio] after low cadmium concentration exposure]

High concentration of heavy metals or long time exposure to low concentrations of these metals can usually decrease the hematological indices in fish. Therefore the aim of this study was to indicate changes in hematology and serum chemistry of common carp [cyprinus carpio] after low cadmium concentration exposure. 60 apparently healthy common carp [mean weight of 700g] divided in two groups and transfred to 1000 liter indoor fiberglass tanks under controlled conditions. Treatment group was exposed to low concentration of cadmium [30ppb]. Blood were exsanguinated randomly from 5 fish in each group through the caudal vein at days 15 and 30 of exposure. The hematological and biochemical parameters [WBC, RBC, different count, hematocrit, total protein, albumin and globulin concentrations, albumin: globulin ratio, LDH, ALT, and AST] were determined. Results revealed that WBC counts decreased significantly on the 15th day of exposure [p<0.05]. Furthermore, WBC counts decreased significantly on the 30th day of exposure [p<0.05]. The levels of LDH after day 30 of exposure, significantly increased in the test group compared to the control. In the test group, LDH levels significantly increased at the 30th day of exposure. No significant differences have been observed between control and test groups in respect to the other parameters. This study showed that the exposure time for sublethal concentration of cadmium is an important factor for increasing the LDH levels in common carp

Efectos del cadmio sobre las glándulas salivales de rata: durante la lactancia / Effects of cadmium on the rat salivary glands: during lactation

El cadmio (Cd), presente en el aire, agua potable y alimentos, tiene potencial para afectar la salud humana, principalmente en las regiones altamente industrializadas. El Cd además de afectar la función placentaria, puede atravesar la barrera placentaria y perjudicar directamente el desarrollo fetal. En virtud de que el organismo es particularmente susceptible a la exposición al Cd durante el período perinatal, y que ese metal puede ser excretado en la leche, el objetivo del presente trabajo fue estudiar los efectos de la exposición continua a agua potable conteniendo bajos niveles de Cd durante la lactancia sobre las glándulas salivales de la rata. Ratas hembra recibieron agua potable conteniendo 300mg/l de CdCl2 ad libitum durante toda la lactancia. Animales control recibieron un volumen similar de agua potable sin Cd. Las ratas lactantes (21 días de edad) fueron sacrificadas con una dosis letal de anestésico. Las glándulas salivales fueron separadas, fijadas en "alfac" por 24 h, y cortadas seriadamente. Cortes de 6 µm de espesor fueron teñidos con hematoxilina y eosina. Fueron estimados los parámetros nucleares, los volúmenes citoplasmático y celular, la relación núcleo/citoplasma, densidad numérica, densidad superficial, diámetros y espesor de las paredes de las estructuras glandulares. El peso medio corporal fue 34,86 g para la rata control y 18,56 g para la tratada. Histológicamente, los adenómeros glandulares fueron significativamente menores y los conductos glandulares fueron similares en ambos grupos. La estroma fue más abundante en los animales tratados. En conclusión, las glándulas salivales (submandibular, parótida y sublingual) mostraron retardo del crecimiento en los animales intoxicados por Cd.

Cadmium (Cd) in air, drinking water and food has the potential to affect the health of people, mainly those who live in highly industrialized regions. Cd affects placental function, can cross the placental barrier and directly modify fetal development. Once the organism is particularly susceptible to the exposition to the Cd during the perinatal period, and that this metal can be excreted in the milk, the aim of the present work was to study the effects of the constant exposition to drinkable water containing low levels of Cd during the lactation, on the salivary glands of the rat. Female rats received ad libitum drinking water containing 300mg/l of CdCl2 throughout the whole lactation. Control animals received a similar volume of water without Cd. Lactant rats, (21 day old) were killed by lethal dose of anesthetic. The salivary glands were separated, fixed in "alfac" solution for 24 h, and serially sectioned. The 6mm thick sections were stained with hematoxylin and eosin. Nuclear glandular parameters were estimated, as well as cytoplasm and cell volume, nucleus/cytoplasm ratio, number and surface density, diameters and cell thickness. Mean body weight was 34.86 g for the control group and 18,56 g for the Cd-treated group. Histologically, the glandular acini were significantly smaller, the gland ducts were similar in both groups studied. The connective tissue was more abundant. In conclusion, the salivary glands (submandibular, parotid and sublingual) showed retarded growth after Cd intoxication.

Hormesis response of marine and freshwater luminescent bacteria to metal exposure

The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II), Zn (II), Cd (II) and Cr (VI) on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.

Efectos de exposición aguda a cadmio en la acción de estrógenos en útero de rata impúber / Effects of acute exposure to cadmiun on response to estrogen in the prepuberal rat uterus

Background: Few information is available about uterine effects of Cadmium (Cd) exposure, where toxic agents affecting the female genital tract interact with estrogen (E) receptors, modifiying myometrial activity and the menstrual cycle, causing dysmenorrhea, infertility and spontaneous abortion. No information exists whether prenatal or early postnatal exposure may cause any gynecologic persistent adverse effect. Our finding of a second mechanism of E interaction and differences between E receptors in the various uterine cell types suggests that Cd may affect differently E interaction in each cell-type. Objective: Evaluate a possible selective effect of acute Cd exposure on E action in the uterus during prepuber age. Method: Female prepuber rats exposed to Cd 4 mg/kg and 2 hours later, treated with Estradiol-17² 0,3 mg/kg. A myometrial sample was obtained under anaesthesia 24 hours after E treatment and histologically processed for the quantification of E responses on different uterine cell-types. Results: Cd exposure potentiates E-induced uterine eosinophilia and endometrial edema and inhibits E-induced cell hypertrophy in circular myometrium and cell proliferation in luminal myometrium. Cd, in the absence of hormone stimulation, causes a slight cell hypertrophy in circular myometrium. Conclusions: Acute exposure to Cd affects differently various responses to E in the different uterine cell-types. Future studies should verify whether this effect explains Cd-induced infertility, postpubertal sex organ development and whether prenatal or early postnatal exposure to Cd induces delayed persistent effects.

Antecedentes: Existe poca información sobre efectos del cadmio (Cd) en el útero. En mujeres altera la actividad miometrial, el ciclo menstrual y causa dismenorrea, abortos espontáneos, infertilidad y mortinatos. No existe información si la exposición prenatal o postnatal temprana causa efectos ginecológicos diferidos persistentes. Los tóxicos que afectan el útero suelen interactuar con receptores de estrógeno (E). Nuestro hallazgo de un segundo mecanismo de acción de E y de diferencias entre receptores de E de los diversos tipos celulares uterinos hacen posible que el Cd interactúe con los E en forma diferente en cada tipo celular. Objetivos: Buscar un posible efecto selectivo de la exposición aguda a Cd con algunas respuestas a E en útero de rata durante la edad prepuberal. Métodos: Ratas hembra impúberes recibieron 4 mg Cd/kg p.c. y 2 h después se trataron con 0,3 mg estradiol-17(3/kg p.c; los úteros fueron obtenidos bajo anestesia a las 24 h del tratamiento con E. Los úteros se procesaron para la cuantificación de respuestas a E en cada tipo celular por separado. Resultados: La exposición a Cd incrementa la eosinofilia uterina y edema endometrial inducidos por E; inhibe las siguientes respuestas a E: hipertrofia celular en miometrio circular, proliferación celular en epitelio luminal y miometrio. En ausencia de hormona, el cadmio causa una leve hipertrofia celular en miometrio circular. Conclusiones: La exposición aguda a Cd afecta de manera diferente las respuestas a E en los diversos tipos celulares uterinos de rata prepuberal. Futuros estudios deberán verificar si este efecto explica la infertilidad causada por exposición a Cd, afecta el desarrollo postpuberal de los órganos sexuales, e investigar si la exposición prenatal o postnatal temprana induce efectos diferidos persistentes, como puede ocurrir en población infantil prenatalmente expuesta a Cd.

Impact of Ni(II), Zn(II) and Cd(II) on biogassification of potato waste.

A study was conducted on anaerobic digestion of potato waste and cattle manure mixture, inoculated with 12% inoculum and diluted to 1:1 substrate water ratio at 37 +/- 1 degrees C. Initially pH of substrate was found to be 4.5 to 5.0. Lime and sodium bicarbonate solutions were employed to adjust the pH to 7.5. Biogas production continued up to 10 and 7 days, when lime and sodium bicarbonate solutions were used to adjust the pH, respectively. Biogassification potential was studied in response to different ratio of waste and cattle manure. Biogas production rate was higher when potato waste and cattle manure were used in 50:50 ratio. Effect of two different concentrations (2.5 and 5.0 ppm) of three heavy metals viz. (Ni (II), Zn (II) and Cd (II)) on anaerobic digestion of substrate (potato waste--cattle manure, 50:50) was studied. At 2.5 ppm, all the three heavy metals increased biogas production rate over the control value. The percentage increase in biogas production over the control was highest by Cd, followed by Ni and Zn. In all the treatments, methane content of biogas increased with increase in time after feeding. Various physico-chemical parameters viz. total solids, total volatile solids, total organic carbon and chemical oxygen demand considerably declined after 7 days of digestion and decline was greater in presence of heavy metals as compared to control. The physico-chemical parameters revealed maximum decrease in the presence of 2.5-ppm concentrations of heavy metals with the substrate. Among all the three heavy metals employed in the study, Cd++ at 2.5 ppm was found to produce maximum biogas production rate. The use of three heavy metals to enhance biogas production from potato and other horticultural waste is discussed.

Geobacillus stearothermophilus LV cadA gene mediates resistance to cadmium, lead and zinc in zntA mutants of Salmonella entérica serovar Typhimurium

Salmonella entérica serovar Typhimurium cells expressing the cadA gene of Geobacillus stearothermophilus LV exhibit a hypersensitive phenotype to cadmium chloride. Deletion of the ORF STM3576 from the Salmonella genome resulted in cadmium, lead and zinc sensitivity, confirming that this ORF is a homologue of the zntA gene. The observed sensitivity was reverted upon expression of the G. stearothermophilus LV cadA gene. These results indicate that the cadA gene product is involved in Cd, Pb and Zn resistance as a classical P-type ATPase and strongly suggest that the observed hypersensitive phenotype to these metals can be related to the function of the host ·zntA gene product.

Heat shock protein 27 interacts with vimentin and prevents insolubilization of vimentin subunits induced by cadmium

Vimentin is an intermediate filament that regulates cell attachment and subcellular organization. In this study, vimentin filaments were morphologically altered, and its soluble subunits were rapidly reduced via cadmium chloride treatment. Cadmium chloride stimulated three major mitogen-activated protein kinases (MAPKs): extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, and led apoptotic pathway via caspase-9 and caspase-3 activations. In order to determine whether MAPKs were involved in this cadmium-induced soluble vimentin disappearance, we applied MAPK- specific inhibitors (PD98059, SP600125, SB203580). These inhibitors did not abolish the cadmium-induced soluble vimentin disappearance. Caspase and proteosome degradation pathway were also not involved in soluble vimentin disappearance. When we observed vimentin levels in soluble and insoluble fractions, soluble vimentin subunits shifted to an insoluble fraction. As we discovered that heat- shock protein 27 (HSP27) was colocalized and physically associated with vimentin in unstressed cells, the roles of HSP27 with regard to vimentin were assessed. HSP27-overexpressing cells prevented morphological alterations of the vimentin filaments, as well as reductions of soluble vimentin, in the cadmium-treated cells. Moreover, HSP27 antisense oligonucleotide augmented these cadmium-induced changes in vimentin. These findings indicate that HSP27 prevents disruption of the vimentin intermediate filament networks and soluble vimentin disappearance, by virtue of its physical interaction with vimentin in cadmium-treated SK-N-SH cells.

Subcellular localization of Cd in the root cells of Allium sativum by electron energy loss spectroscopy.

The ultrastructural investigation of the root cells of Allium sativum L. exposed to three different concentrations of Cd (100 mM, 1 mM and 10 mM) for 9 days was carried out. The results showed that Cd induced several significant ultrastructural changes high vacuolization in cytoplasm, deposition of electron-dense material in vacuoles and nucleoli and increment of disintegrated organelles. Data from electron energy loss spectroscopy (EELS) revealed that Cd was localized in the electron-dense precipitates in the root cells treated with 10 mM Cd. High amounts of Cd were mainly accumulated in the vacuoles and nucleoli of cortical cells in differentiating and mature root tissues. The mechanisms of detoxification and tolerance of Cd are briefly explained.

Efectos del cadmio en la mucosa yugal de la rata durante la lactancia: estudio morfológico e histométrico / Effects of cadmium on the rat jugal mucosa during lactation: morphological and histometrical study

El cadmio del aire, agua y alimentos tiene potencial de afectar la salud de las personas, principalmente de aquellas que viven en regiones industrializadas. El cadmio afecta la función placentaria, pudiendo atravesar la barrera trofoblástica y provocar alteraciones en el desarrollo del feto; puede, también, ser excretado por la leche. El organismo es particularmente susceptible a la exposición al cadmio en el periodo perinatal. Se estudió el efecto de la intoxicación por cadmio en el epitelio vestibular y suelo de la boca de ratas expuestas a niveles bajos de cadmio en el agua del bebedero, durante la lactancia. Las ratas recibieron agua ad libitum conteniendo 300 mg/l de CdCl2 durante los 21 días de lactancia. Los animales controles recibieron un volumen similar de agua sin cadmio. Las crías fueron sacrificadas mediante sobredosis anestésica en el 21 día. Las cabezas de los animales fueron separadas, fijadas en solución de alfac. Las regiones del paladar y de la mandíbula fueron cortadas seriadamente en planos frontales, a nivel de los primeros molares, efectuándose cortes de 6 µm de grosor, los cuales fueron teñidos con H-E. Los parámetros nucleares del epitelio fueron estimados, así como también, los volúmenes citoplasmático y celular, relación núcleo-citoplasma, densidad numérica y superficial, y el espesor del epitelio. El peso corporal medio de las crías fue de 34,86 g en el grupo control y de 18,56 en el grupo tratado. Histológicamente, el epitelio se mostró adelgazado, constituido por células abundantes y menores. En el presente experimento, el cadmio ocasionó un cuadro de hipotrofia epitelial, indicando una acción directa en las células epiteliales de la mucosa oral, además de provocar el retardo del desarrollo de las crías intoxicadas.

Nuclear zinc in liver of cadmium and zinc treated rats.

X-ray microanalysis was performed to detect quantitatively, the variation of the nuclear zinc in the liver cells of rats. The nuclear zinc concentration showed statistical decrease and increase in response to cadmium and zinc treatments, respectively. The results suggest that the liver responds differently to cadmium and zinc treatments. The difference in response to either treatment may reflect different mechanisms of zinc transport and metabolism in the liver. The difference in binding affinity of metallothionein (MT) may suggest the involvement of Mt in the metabolism and transport of zinc, an effect, which may be modified by treatment.

Acute and chronic effects of cadmium on blood homeostasis of an estuarine crab, Chasmagnathus granulata, and the modifying effect of salinity

Whole body oxygen consumption and some hemolymph parameters such as pH, partial pressure of gases, level of ions and lactate were measured in the estuarine crab Chasmagnathus granulata after both acute (96 h) and chronic (2 weeks) exposure to cadmium at concentrations ranging from 0.4 to 6.3 mg/l. In all instances, the crabs developed hemolymph acidosis, but no respiratory (increased PCO2) or lactate increases were evident. Hemolymph levels of sodium and calcium were always increased by cadmium exposure. The chronic toxicity of cadmium was enhanced at 12 0/00 salinity, even causing a significantly higher mortality in comparison with the higher salinity (30 0/00) used. A general metabolic arrest took place at 12 0/00 salinity in the crabs chronically exposed to cadmium, as indicated by decreases of oxygen consumption and PCO2, an increase of PO2, along with no changes in lactate levels. These imbalances were associated with severe necrosis and telangiectasia in the respiratory gills, probably leading to respiratory impairment and finally histotoxic hypoxia and death of the animals

Ultrastructure of the dorsal prostate gland in zinc and cadmium treated rats

Changes in the ultrastructure of the dorsal lobe of the prostate gland from cadmium and zinc treated rats were studied using transmission electron microscopy. Two groups of rats [10 in each group] were injected subcutaneously [s.c.] with 2mg/kg cadmium chloride [Cdc12] and 10mg/kg zinc sulfate[ZnSO4], respectively. A third group was injected s.c. withnormal saline and served as a control. Tissues from the dorsal lobe of the prostate gland from the three groups were processed for transmission electron microscopy. Epithelial cells of the dorsal lobe of prostate gland from the cadmium and zinc treated groups showed a considerable variation in the morphology of the rough endoplasmic reticulum, Golgi comlex, secretory vesicles, mitochondria, and microvilli as compared with the control group. These variations may be due the direct effect of zinc and cadmium, and/or due to meta llothionein [MT] synthesis induced by zinc and cadmium. Further studies will be required to identify the active factor[s]

Influence of cadmium on growth and development of Vicia faba Linn.

Influence of cadmium (Cd) on growth and development of broad bean (V. faba) was assessed in pot cultures with cadmium iodide (CdI2) in different concentrations ranging from 15 to 500 mg per kg of soil. There was a decline in plant height and total dry weight. Root size decreased most significantly with a corresponding reduction in the frequency of root nodules. Total soluble protein in leaf, stem and root suffered a pronounced loss with increasing concentration of cadmium. Chlorophyll a was the most sensitive pigment followed by chlorophyll b and carotenoids. Nitrate reductase activity too was adversely affected. Cadmium contamination induced abnormalities in stomata and trichomes.

Influence of metal ions on structure and catalytic activity of papain.

Papain is an endoprotease belonging to cysteine protease family. The catalytic activity of papain in presence of two different metal ions namely zinc and cadmium has been investigated. Both the metal ions are potent inhibitors of the enzyme activity in a concentration dependent manner. The enzyme loses 50% of its activity at 2 x 10(-4) M of CdCl2 and 4 x 10(-4) M of ZnCl2. It is completely inactivated above 1 x 10(-3) M concentration of either ZnCl2 or CdCl2. Of the two metal ions zinc with a ki value of 5 x 10(-5) M is a more potent inhibitor than cadmium which has a ki value of 8 x 10(-5) M. Both the metal ions have higher affinity for active site than the substrate. At concentrations above 1 x 10(-2) M of metal ions the inhibition is not reversible. Calorimetric studies showed decreased thermal stability of papain upon binding of these metal ions. Far UV circular dichroic spectral data showed only small changes in the beta-structure content upon binding of these metal ions. These data are also supported by decrease in the apparent thermal transition temperature of papain by 5 degrees C upon binding of metal ions indicating destabilization of the papain molecule. The mechanism of both partial and complete inactivation of papain in presence of these two metal ions both at lower and higher concentration has been explained.

Opiatergic participation in the thirst-inhibiting effect of acute third ventricle injections of cadmium (Cd 2+ ) and lead (Pb 2+ )

We have previously demonstrated that acute third ventricle injections of both lead and cadmium prevent the dipsogenic response elicited by dehydration or by central injections of dipsogenic agents such as angiotensin II, carbachol and isoproterenol in rats. We have also shown that the antidipsogenic action of cadmium may be due, at least in part, to activation of thirst-inhibitory central serotonergic pathways. In the present paper we show that in Wistar male rats the antidipsogenic effect of both lead acetate (3.0 nmol/rat) and cadmium chloride (3.0 nmol/rat) may be partially dependent on the activation of brain opiatergic pathways since central injections of naloxone (82.5 nmol/rat), a non-selective opioid antagonist, blunt the thirst-inhibiting effect of these metals. One hundred and twenty minutes after the second third ventricle injections, dehydrated animals (14 h overnight) receiving saline + sodium acetate displayed a high water intake (7.90 ñ 0.47 ml/100 g body weight) whereas animals receiving saline + lead acetate drank 3.24 ñ 0.47 ml/100 g body weight. Animals receiving naloxone + lead acetate drank 6.94 ñ 0.60 ml/100 g body weight. Animals receiving saline + saline drank 8.16 ñ 0.66 ml/100 g body weight whilst animals receiving saline + cadmium chloride drank 1.63 ñ 0.37 ml/100 g body weight. Animals receiving naloxone + cadmium chloride drank 8.01 ñ 0.94 ml/100 g body weight. It is suggested that acute third ventricle injections of both lead and cadmium exert their antidipsogenic effect by activating thirst-inhibiting opioid pathways in the brain

Aerobic growth of motile and non-motile bacteria an the surface of solid culture medium in the presence of the heavy metal and ionic salts at two temperatures

Threshold concentrations of heavy metal and ionic salts defining the range of Concentrations, that do not suppress growth, were determined in tryptic soya agar medium. It has been found that the salts of NH4, Mg, Cd and Hg at low concentrations disrupt the symbiotic relationship between the solid surface culture medium and the microorganisms, but do not suppress the growth of the bacteria. These compounds have been included under two different groups as infection inhibitors [Cd and Hg] and as an infection stimulators [NH4, Mg and K]

Effect of cadmium and captopril on serum angiotensin converting enzyme activity in rats.

The effects of captopril (2 mg/kg i.p.) and cadmium (1 mg/kg i.p.) at three different time points (30, 60, 180 min) on serum angiotensin converting enzyme (ACE), blood pressure (BP) and heart rate (HR) were examined in male Sprague-Dawley rats. Captopril produced significant inhibition of ACE at 60 and 120 minutes, while maximum fall of BP (15 mm Hg) was obtained at 30 minutes post-test drug treatment. Heart rate at the three different time intervals did not change significantly. ACE levels in the serum were significantly reduced at different time intervals (30, 60, 120 min) in the cadmium-treated group as compared with controls (p < 0.05). Cadmium increased the blood pressure and heart rate of rats. The results indicate that while both cadmium and captopril produce different effects on blood pressure and heart rate, both of these also inhibit the serum ACE in rats.

Lead (Pb+) and cadmium (Cd2+) inhibit the dipsogenic action of central beta-adrenergic stimulation by isoproterenol

We have previously demonstrated that acute third ventricle injections of both Pb2+ and Cd2+ impair the dipsogenic response elicited by three different situations: dehydration and central cholinergic or angiotensinergic stimulation. beta-Adrenergic activation is part of the multifactorial integrated systems operating in drinking behavior control in the central nervous system. In the present study acute third ventricle injections of Pb2+ (3,30 and 300 pmol/rat) or Cd2+ (0.3, 3 and 30 pmol/rat) blocked the dipsogenic response induced by third ventricle injections of isoproterenol (ISO; 160 nmol/rat) in a dose-dependent manner. Normohydrated animals receiving ISO + NaAc (sodium acetate) or saline (controls) displayed a high water intake after 120 min (ISO + saline = 5.78 ñ O.54 ml/lOO g; ISO + NaAc = 6.00 ñ O.6 ml/lOO g). After the same period,animals receiving ISO but pretreated with PbAc at the highest dose employed (300 pmol/rat) drank O.78 ñ O.23 ml/lOO g while those receiving ISO and pretreated with the highest dose of CdCl(2)(30 pmol/rat) presented a water intake of O.7 ñ O.30 ml/lOO g. Third ventricle injections of CdCl(2) (3 nmol/rat) or PbAc (3 nmol/rat) did not modify food intake in rats deprived of food for 24 h. Thus, general central nervous system depression explaining the antidipsogenic action of the metals can be safely excluded. It is concluded that both Pb2+ and Cd2+ inhibit water intake induced by central beta-adrenergic stimulation.

Effect of different cadmium concentration on Growth. photosynthesis and ion relation of wheat

The effect of Cd2+ on growth, photosynthesis and ion relations of hydroponically grown wheat plants was studied in a greenhouse experiment. Four different concentrations of Cd2+ [0, 1, 5 and 10 muM cadmium sulfate] were applied. Root and shoot dry weight, relative growth rate [RGR], net assimilating ratio [NAR] were significantly reduced by 5 and 10 muM Cd. The application of Cd2+ resulted in reduction of photosynthesis and transpiration. Data concerning the accumulation of cadmium in root and shoot as function of time and external cadmium concentration indicated that cadmium content of the shoot was low as compared with that in root. The application of Cd2+ was found to affect the nutrient concentration of root and shoot tissue and their uptake by plant