Involvement of adrenal and thyroid activity in the annual testicular regression of red headed bunting (Emberiza bruniceps)

Thyroid and adrenal activities are closely associated with reproductive cycle and any alteration in these endocrine functions may cause changes in the pituitary-gonadal axis. To understand this interrelationship during testicular senstive phase (month of April) male birds were injected with metapyrone(corticosterone synthesis blocks 1 microg/bird/day & 10 microg/bird/day) and newmercazol (thyroxine synthesis blocks 10 microg/bird/day) over a period of 12 weeks. During late breeding phase (month of August) two sets of birds having large gonad (photosensitive) and regressed gonad (photorefractory) were injected with metapyrone (10 microg/bird/alternate day). Results indicate that decreased activity of both adrenal and thyroid, extended the breeding phase but rate of regression decreased only in the case of bird receiving higher level of metapyrone.However,in the second group rate of gonadal regression was slow only in those bird where treatment was started during photosensitive phase. It may be suggested that optimum level of activity of adrenal and thyroid function are essential for termination of reproduction and any alteration in these function may alter seasonal pattern of neuroendocrine gonadal axis.     

Effects of temperature on testicular cycle of wild birds Black headed munia and Spotted munia

A long term investigation was made on the effects of temperature in the reproduction of tropical wild birds, Black headed munia, Munia malacca and Spotted munia, Lonchura punctulata. In Spotted munia delayed gonadal development as well as regression were observed in 12 degrees C treated group. In 20 degrees C treated birds the testicular volume was significantly less in the month of September and October and was significantly more in November compared to the corresponding control values. In 27 degrees C treated birds delay in testicular development was observed. In Black headed munia delayed gonadal development and regression was observed in 12 degrees C and 20 degrees C treated groups. But maximum gonadal development Delayed regression was also noticed in 20 degrees C group. In 27 degrees C treated group an inhibition of the testicular development was noticed during progressive phase (September). Present findings suggest that neither temperature nor continuous illumination could alter the circannual nature of testicular cycle in spotted munia indicating that temperature acts only as supplementary factor in the reproduction of these two bird models. We further suggest that temperature effects are mediated through changes in thyroxine levels.     

Cesium inhibition of motor activity in comparison to Lithium and Rubidium †

The biochemical and toxicological significance of cesium is scarcely understood, and could be evaluated in comparison with lithium widely used as a psychotropic drug. Two male Wistar rat groups of 200–220 g are administered independently, lithium, sodium, rubidium and cesium chloride, in doses of 3mEq/Kg/day (0.024 Eq/L drinking water) during 29 days. Motor activity was measured after the injection of 70 mg pargyline/Kg animal i.p. as inhibitor of MAO A + B with an activimeter of Tedeschy type. Accumulative movements per minute are presented in function of time. Total brain proteins, alkaline and acid phosphatases and blood parameters, haematocrit, haemoglobin and erythrocytes, were determined.

The maximal increase of motor activity was seen in rats treated with RbCl 2 h after the pargyline administration and the diminution was Rb>Li>Cs. Cesium induced a decrease of the total serum protein concentration from 6.39 ± 0.1 to 5.8±0.5mg/100ml serum in controls. Acid and alkaline phosphatase were decreased in cesium treated rats. The three determined blood parameters, haematocrit, haemoglobin and erythrocytes, show also a decrement with cesium treatment compared to the control ones.     

Influence of hypothyroidism on oxidative stress,c-Fos expression,cell cycle,and apoptosis in rats testes

The molecular basis of male reproduction for cross-regulation between androgen and thyroid hormone axes is still rudimentary. This study aims to define a possible mechanism of hypothyroidism-induced reproductive influence with respect to sex hormone, mineral, sperm motility, oxidative stress, c-Fos expression, cell cycle, and apoptosis in rat testes. The Wistar rats were randomly divided into control group (NS) and hypothyroidism group [1 ml/100g BW/day, 0.1% propylthiouracil (PTU)] by intragastric gavage for 60 days. Blood samples were collected to measure the serum levels. The epididymis was excised to measure sperm motility and testes were excised to measure mineral, oxidative stress, c-Fos expression, cell cycle, and apoptosis. After 60 days, body weight, relative testes weight, triiodothyronine, and total thyroxine were all significantly decreased, whereas thyroid stimulating hormone was increased in the hypothyroidism group. A significant increase in sex hormone level of estradiol (E2) and significant decreases in testosterone (T) and T/E2 ratio were observed following PTU treatment. And sperm quality was also significantly changed. There were significant decreases in the contents of calcium (Ca²⁺) and zinc (Zn²⁺). On the other hand, malondialdehyde and hydrogen peroxide contents significantly increased, whereas the activity of superoxide dismutase, catalase and nitric oxide synthase and nitric oxide content significantly decreased in hypothyroid rats. The mRNA and protein expressions of c-Fos decreased significantly. The cell percentage in G0/G1 phase increased significantly, whereas decreased significantly in S and G2/M phases. Also, a significant increase in testicular cell apoptosis was observed in hypothyroid-treated rats. These results suggested that hypothyroidism could affect reproductive function in the form of changed sex hormone levels, sperm motility and testicular Ca²⁺ and Zn²⁺, and enhanced oxidative stress leading to c-Fos abnormal expression and increased apoptosis.     

Adverse effects of mercuric chloride on thyroid of mice, Musculus albinus and pattern of recovery of the damaged activity

The protective role of "essentiale phospholipids" (EPL) on mercury induced thyroid dysfunction with special reference to cholesterol, thyroid peroxidase and thyroxine activity in mice were investigated. The animals were treated with 0.5 ml/day of 0.5 ppm aqueous mercuric chloride for a period of 7, 14 and 21 days. For the recovery 175 mg of EPL was given to mice (already treated with HgCl2) for a period of 7, 14 and 21 days. Daily treatment of HgCl2 for 7, 14 and 21 days decreased serum cholesterol, TPO and T4 activity. Simultaneous administration of EPL (25 mg/mice) restored thyroid function in mice by maintaining serum thyroid hormone concentration almost normal. It increased serum cholesterol, TPO and T4 activity. It appears that the protective effect of EPL against HgCl2 induced thyroid dysfunction is mediated through its antioxidative action.     

Role of nano-powder of Azadirachta indica leaves to regulate the physiological responses and metal uptake in Triticum aestivum seedlings

In the present study different doses (0.05, 2.0 and 5.0?mg per 30?ml nutrient medium) of nano-powder (Azadirachta indica leaves) were applied in Cd contaminated (6?ppm) hydroponic system to regulate the metal uptake in Triticum aestivum (wheat) seedlings. Other physiological attributes including oxidative biomarkers, antioxidants and photosynthetic responses were also assessed. The level of Cd was maximally reduced at the dose of 2.0?mg nano powder per 30?ml nutrient medium by 45 and 49% in the shoot and root, respectively. With the maximum reduction in the Cd uptake at this dose, the generation of oxidative stress markers such as H₂O₂ (12%), MDA (26%) and SOR (20%) content showed maximum reduction in treated seedlings. At different doses of nano-powder, the activities of antioxidative enzymes were also showed significant variation. Further, the photosynthetic O₂ evolution rate was improved with the treatment of nano-powder and the best response was noted at 2.0?mg per 30?ml nutrient medium with the maximum value of fresh shoot biomass (38%). The overall results suggest that, this technique could be easily applied for reducing the metal content and increasing the quality of agricultural crops.     

Evaluation of reproductive and developmental toxicity of cypermethrin in male albino rats

The ever-increasing use of pesticides in the agricultural and public health has become a major cause of sterility in human and various other animals particularly in males. This study was sought to screen the toxic impacts of cypermethrin (synthetic pyrethroid) on reproduction and development. Twenty-four Wistar male rats divided into four groups were orally administered cypermethrin of daily doses 50, 75, or 100 mg?kg^?1 bwt per day for 45 days; and for developmental toxicity, 12 female rats were separated into two groups. Maternal rats (experimental) were administered cypermethrin (100?mg?kg^?1) by gavage daily from 6th to 17th day of gestation, and the control group was dosed only vehicle (olive oil). The body weights, fertility index, biochemical, enzymatic, hormonal, and histopathological parameters were the criteria used to evaluate the toxicity of cypermethrin. Study showed significant decline in the weight of testes, epididymises, seminal vesicles, and ventral prostate, and reduction in sperm counts both in epididymises and testes in chemical-treated animals. Pre- and post- fertility test showed 50%, 80%, and 100% negative results after treatment. A significant degenerative reduction in testicular glycogen and sialic acid was also noted. In contrast, protein and cholesterol levels of testes were significantly increased. In addition, acid phosphatase activity was significantly increased, while alkaline phosphatase, testosterone, leutinizing hormone (LH), and follicle stimulating hormone (FSH) levels were diminished. Histology of testes showed degenerative changes in seminiferous tubules. Cypermethrin exposure during gestation produced adverse effects markedly in females and fetuses.     

Effect of mercuric chloride on circulating hormones in adult albino rats

The effect of mercuric chloride at two different doses, 0.5 mg/kg body weight (low dose), 1 mg/kg body weight (high dose), for 30 days, was seen on the circulating hormones in the mature male albino rats. Testosterone level was markedly decreased in the low dose (P < 0.01) and high dose (P < 0.001) treated animals. The level of luteinizing hormone (LH) was also reduced in the low dose (P < 0.01) as well as in the high dose (P < 0.001) treated animals. However, follicle stimulating hormone (FSH) and prolactin (PRL) levels were found to be decreased only in the high dose (P < 0. 05) treated animals and no change was observed in the low dose treated animals. The changes in the hormone levels caused by the mercuric chloride treatment suggest the dysfunction of pituitary-testicular axis.     

Anti-implantation and anti-fertility potentials of Anethum graveolens L. extracts in rats

Ovarian hormones affected some enzymes in reproductive tissues. Previous studies revealed Anethum graveolens (dill) seed extract elevated ovarian hormones. In this study, we compared the effects of dill seed and leaf extracts on some enzymes activities and infertility potential. Female Wistar rats were divided into three groups of control, dill seed and dill leaf aqueous extracts treated groups. Experimental groups received 1 mL of 0.5 g kg^?1 of each extract orally for 25 days (five estrous cycles). Estradiol, progesterone, luteinizing hormone, and follicle stimulating hormone concentrations were determined. Uterus and ovaries were removed and their glucose-6-phosphate dehydrogenase, lactate dehydrogenase, and alkaline phosphatase activities were measured. Female rats of three groups were mated with untreated males. Fetuses were extracted in the 20th gestational day and their weights and crown rump lengths were measured. Anti-fertility and anti-implantation activities and fertility indices were calculated. Glucose-6-phosphate activity of dill seed treated group increased 1.6 times in the endometrium and 1.7 times in the myometrium. Progesterone concentration and lactate dehydrogenase activity of serum increased in the dill seed treated group compared to the control and dill leaf treated group. A significant decrease was observed in weights and crown rump lengths of fetuses, weights of placenta, and fertility index of the dill seed treated group compared to the control and dill leaf treated group, but its anti-implantation and anti-fertility indices increased. We suggested that high level of glucose-6-phosphate could entail increased oxidative stress in uterus and ovary. High lactate dehydrogenase activity in serum may affect cell membranes. Higher secretion of progesterone caused hormonal imbalance and produced estrous cycle irregularity. It was concluded that dill seed but not dill leaf extract could induce infertility in an animal model.     

Time-dependent effects of chlordane on thyroid histological structure and function in rats

In order to study the time-dependent effects of chlordane on thyroid hormone levels and histological structure in rats, 120 healthy 4-week-old SD rats were divided randomly into 12 groups. Rats in treatment groups were treated orally by gavage with chlordane at a dose of 15 mg kg^?1 for 5, 10, 15, 20, 30, or 40 days, while rats in control group received an equal volume of corn oil. Serum levels of thyroxine (FT4), triiodothyronine (FT3), and thyroid stimulating hormone (TSH) were measured by radioimmunoassay. Sections of thyroids were dyed with hematoxylin–eosin to detect any pathological alterations. In chlordane treated groups, on day 5, changes in serum levels of FT4, FT3, and TSH were not found. On days 10 and 15, serum levels of FT4 and FT3 decreased, accompanied by increased levels of TSH. On days 20, 30 and 40, serum levels of these hormones returned to control values. As for alterations in histology, on day 10–15, follicular epithelium of the thyroid were found to proliferate into two layers in chlordane treated rats. On day 20, in focal areas the two-layer afollicular epithelia were observed to continuously proliferate into 3–4 layers of follicular epithelium, termed hyperplasia plaques. On days 30 and 40, solid buds and secondary follicles to solid buds were detected. The earliest alteration of thyroid hormones in treated SD rats occurred between 5 and 10 days with corresponding histopathologic changes. As the exposure time increased, the serum levels of hormones and histopathology altered in a time-dependent manner.     

Metabolic responses of Azolla pinnata to cadmium stress: photosynthesis,antioxidative system and phytoremediation

This present study deals with the growth, photosynthesis, oxidative stress and phytoremediation character of Azolla pinnata L. exposed to different levels (0.05, 0.1, 0.5, 1.0, 1.5 and 2.0 mg·L^?1) of cadmium (Cd). Significant accumulation of Cd in Azolla fronds was noticed after 24 and 96 h of exposure and the accumulation rate was dose and time dependent. Growth of A. pinnata increased significantly after both exposure times with and without metal. At lower Cd doses (0.05 and 0.1 mg·L^?1), growth and photosynthesis of A. pinnata showed a marginal increase over the respective control, however, at higher Cd doses (0.5, 1.0, 1.5 and 2.0 mg·L^?1), a decreasing trend was noticed. At lower doses, Azolla fronds could counterbalance the negative effect of enhanced levels of superoxide radicals (SOR) and hydrogen peroxide (H₂O₂) through the greater activity of antioxidative enzymes. The decaresing trends in catalase and peroxidase activity at higher Cd doses suggest that Azolla fronds were not able to mitigate the negative effects of H₂O₂, hence an increase in malondialdehyde content was noticed. The study concludes that up to 0.1 ,mg·L^?1 Cd, A. pinnata can flourish and be used as biofertiliser and for phytoremedial purposes in Cd-contaminated fields; beyond this concentration poor growth may restrict its application.     

Age,experience and reproductive performance in a long-lived bird: a hormonal perspective

The ultimate factors influencing age-specific reproductive performance in birds have been widely discussed, and several hypotheses have been suggested to explain why young/inexperienced breeders have lower reproductive success than older individuals. In comparison, proximate factors and, particularly, hormonal mechanisms influencing age-related reproductive performance have received lesser attention. In this paper, we examined how baseline levels of corticosterone and prolactin, two hormones involved in reproduction, changed with age and experience in a long-lived bird, the Black-browed albatross (Thallasarche melanophris) during the brooding stage. Corticosterone levels were not linked to age, whereas prolactin levels increased until individuals reached 15 years of age. First-time breeders had higher corticosterone levels and lower prolactin levels than experienced ones. Corticosterone levels were not correlated with breeding experience among experienced birds, whereas prolactin levels slightly increased with advancing experience. Among experienced breeders, there was no effect of individual quality on corticosterone and prolactin levels. Baseline corticosterone and prolactin levels were respectively, positively and negatively correlated to time spent fasting/brooding on the nest. Moreover, the probability of successfully fledging a chick was negatively related to corticosterone levels, but not to prolactin levels. Elevated corticosterone levels in first time breeders may serve as evidence for depleted body reserves resulting from lower foraging/brooding capabilities and therefore support the constraint hypothesis. Low prolactin levels in young/inexperienced birds may be interpreted either as evidence for their lower breeding capacities (constraint hypothesis) or for their limited breeding investment (restraint hypothesis). Finally, we report, for the first time, the hormonal changes associated with the onset of senescence. The very old and most experienced birds, which had the lowest probability of successfully fledging a young, displayed elevated corticosterone levels and low prolactin levels, possibly indicating a degradation of breeding skills and/or a disruption of the endocrine system in senescent birds.     

Life-history traits and the fate of translocated populations

Attempts to identify predictors and mechanisms of invasion success have been weakened by poor data quality, mostly because monitoring does not begin immediately after introduction events. To overcome this issue, we used data from conservation translocations of threatened bird species. We analyzed information on >1200 translocation events of >150 bird species to investigate how life-history traits affect population establishment measured based on rates of survival and reproduction. Species position along the slow–fast life-history continuum was a key predictor of translocation success. Species with fast-paced life histories were less likely to survive (over both short- and mid-term) and more likely to breed successfully than species with slow life histories. The temporal partitioning of reproductive effort (number of clutches per year) also affected the probability of successful reproduction. Our results illustrate how conservation-motivated reintroduction programs can provide proxies for the initial stages of the invasion process, enabling empirical tests of predictions from life-history theory and informing management.     

Benzene-induced histopathological changes and germ cell population dynamics in testes of Sprague Dawley rats

Benzene has been considered as an occupational hematotoxin and leukemogen. The present study was conducted to determine the effects of oral administration of benzene on reproductive organs and testicular spermatogenesis in rats. Adult rats were divided into three weight matched groups (Gr. I-III) containing 6 each. Gr. I rats received vehicle only and served as control. Rats in Gr. II and III were fed orally with 0.5 and 1 ml kg(-1) dose of benzene for 14 and 9 days, respectively and autopsy was done on 15th and 10th day. Food and water intake and gross behavioral changes were recorded daily during the entire treatment. Results showed no significant change in reproductive organ weights viz. testis, epididymis and ventral prostate in benzene-treated (0.5 or 1 ml kg(-1)) rats than that in controls. But, caused a significant decrease (p < 0.005) in weights of seminal vesicles in rats treated with both 0.5 and 1 ml kg(-1) doses compared to control. In contrast, at higher dose (1 ml kg(-1)) of benzene, significant (p < 0.001) decline in body weight and 100% mortality was observed on day 10 of autopsy. In treated rats, testicular cytotoxicity was marked by multinucleated giant cells formation, cytoplasmic vacuolization, pyknosis of nuclei, chromatolysis, desquamation and dissolution of germ cells in tubular lumen. The quantitative analysis of spermatogenesis showed a significant (p < 0.001) decrease in number ofA-spermatogonia (in 1 ml kg(-1) dose only), primary spermatocytes (non-pachytene and pachytene) and spermatids (round and elongated) in treated as compared to control rats. The diameters of testicular tubules and Leydig cells nuclei were also significantly (p < 0.001) reduced in treated rats. A steady loss in food and water intake recorded and signs of ill health were observed in treated (0.5 or 1 ml kg(-1)) rats. Results of the study indicated antitesticular lantispermatogenic effects of benzene at 0.5 and 1 ml kg(-1) dose in rats.     

Cybil induced hepatobiochemical changes in wistar rats

Cybil, 25%EC formulation of Cypermethrin, induces biochemical changes in the liver of wistar rats after oral intubation of the same at acute (one day) and subacute (7, 14 and 21 days) levels. The changes were tallied with the controls run simultaneously. LD50 of Cybil was estimated to be 622mg/kg body weight The acute dose is 80mg/kg body weight exposed for one day i.e. 24 hours and subacute dose is 4mg/kg body weight exposed for 7, 14 and 21 days. When compared with the control values, both the doses enhanced the level of glycogen, cholesterol, total lipid and acid phosphatase activities, while decreased activity of alkaline phosphatase. Alterations in glycogen, cholesterol, total lipid, acid phosphatase and alkaline phosphatase resulted in the impairement in liver physiology.     

入侵藤本薇甘菊的耐盐能力

薇甘菊Mikania micrantha Kunth为原产中南美洲的入侵藤本植物,现已在全球热带和亚热带地区照成严重的生态问题。野外观察发现薇甘菊已在珠三角沿海植被中滋生。为揭示薇甘菊的耐盐能力及其对滨海盐生植被的潜在危害性,分别对薇甘菊种子、根系和茎干在不同盐度胁迫下的响应进行了测定。在珠三角地区采集了薇甘菊3个批次的种子,并选取珠江三角洲6种常见植物（菊科假臭草Eupatorium catarium、藿香蓟Ageratum conyzoides、野茼蒿Crassocephalum crepidioides、鬼针草Bidens pilosa、翅果菊Pterocypsela indica和旋花科小花假番薯Ipomoea triloba）作为对照,测定了它们在不同NaCl盐度（质量分数）胁迫下的萌发率和幼苗生长;为揭示薇甘菊种子是否可由海水传播,将薇甘菊和对照植物假臭草、藿香蓟和鬼针草在不同盐度条件下浸泡不同时间后解除胁迫再观测其种子萌发率;为确定薇甘菊能否在滨海盐土中无性繁殖,分别对薇甘菊的根系和茎干在盐水浸泡下的植株生长进行了测定。研究结果表明：1）总体而言,薇甘菊3个种群在≤0.6%盐度胁迫下的种子萌发率均与对照组无显著差异,个别种群的这一阈值可高达1.5%,明显高于其他对照植物;同一盐度胁迫条件下,薇甘菊幼苗根系和苗高生长受抑制程度明显低于对照植物。2）即使经高达3.0%盐度胁迫浸泡长达12 d后,薇甘菊、藿香蓟和假臭草种子的萌发率也没有受到显著影响,而鬼针草种子的萌发率有明显下降;四种植物受浸泡后萌芽的幼苗生长均正常。3）薇甘菊根系受0.5%盐度胁迫时没有植株死亡,但苗高增长仅为对照组的53.3%;根系在1.0%盐度胁迫下有95%的植株能存活至少25 d,但苗高增长仅为对照的18.9%;根系在≥1.5%盐度胁迫下薇甘菊无法存活。4）被清水浸泡的薇甘菊茎茎叶均能存活且在全部被浸泡的节上萌芽。当薇甘菊茎干受≥1.0%盐水浸泡时,受浸泡的叶片全部死亡,在1.0%、2.0%和3.0%盐度胁迫下受试茎第21天的死亡率分别为42.9%、40.9%和86.4%。以上结果表明薇甘菊对盐生生境具一定的适应能力,可能通过种子萌发或无性繁殖扩张的方式对滨海盐生植被构成威胁,应当引起重视。     

Influence of pH, salt concentration and temperature on the growth of Aeromonas hydrophila

The influence of environmental factors on the growth of Aeromonas hydrophila was investigated Four isolates (AH 37, AH 79, AH 86 and AH 100) were exposed to various environmental factors such as pH, salt concentration and temperature in laboratory condition. All the four isolates showed more or less similar growth at pH 7.0, 8.0 and 9.0 at 30 degrees C and 5 degrees C. At pH 5.0, 6.0 and 10.0, the log number of cells was found to be lesser than that of pH 7.0, 8.0 and 9.0 at both 30 degrees C and 5 degrees C. The results of the influence of salt concentration on the growth of Aeromonas hydrophila revealed that NaCl concentration of 0.5%, 1.0% and 2.0% favored the growth of this organism at both 30 degrees C and 5 degrees C. Increase in the salt concentration resulted in the growth of the decrease of this organism. Three percentages and 4% salt concentration moderately supported the growth of the organisms in the medium whereas at 5.0% NaCl concentration, there was no growth. Moderate growth of A. hydrophila at 5 degrees C is an interesting observation. The ability to grow at salt concentration between 0.5%, 4.0% under acidic and alkaline conditions pose a problem in the preservation of seafoods. These criteria may account for modified preservation techniques.     

The effects of bisphenol A on sex hormone levels of F0 female rats and F1 male rats during weaning period

The effects of bisphenol A (BPA) were examined on sex hormones of F1 generation male rats during weaning period. Female rats were exposed to BPA from day 0 after pregnancy to the weaning period at doses of 50, 100, or 200 mg kg^?1. The sex hormone levels of F1 generation male rats were determined. This study shows that F0 generation female rats fed with 200 mg kg^?1 BPA had a significantly higher serum prolactin (PRL) levels at the end of weaning. Significantly higher levels of serum estradiol (E₂) were also found in female rats fed 100 or 200 mg kg^?1 BPA. Serum levels of E₂ in F1 male generation rats were higher in treatment groups compared to control groups while serum testosterone (T) levels were lower. Follicle stimulating hormone (FSH) in F1 generation rats fed 200 mg kg^?1 was markedly decreased. The relative testicular weights were significantly less in 100 and 200 mg kg^?1 BPA groups. BPA was found to alter the sex hormone levels in F1 male rats during weaning period and thus disrupted endocrine functions.     

Studies on comparative population growth of some species of the rotifer Lecane (Rotifera)

We compared the population growth patterns of 5 species of the rotifer genus Lecane [(L. quadridentata (Ehrenberg, 1830), L. comuta (Muller, 1786), L. papuana (Murray, 1913), L. unguitata (Fadeev, 1925) and L. pyriformis (Daday, 1905)] ranging in adult average body size from 30 to 140 microm. All species were cultured under laboratory conditions for 25-30 days using the green alga Scenedesmus acutus as the exclusive diet, at a density of 1.0 x 10(6) cells ml(-1) at 24 degrees C. Regardless of the species, lecanids reached their peak population densities after 4 weeks. Peak population densities ranged from 15 to 320 ind. ml(-1), depending on body size. There was an inverse curvilinear relation between body lengths and peak population abundances (densities) of the Lecane species. Egg ratios (eggs per female) for the tested species were < 0.6 during the exponential phase but declined to 0.1 (or lower) as the population density increased. The rates of population increase for the lecanids were in general lower(0.10 to 0.21 day (-1)) than other well-studied rotifer species including members of Brachionidae.     

Demonstration of sperm head shape abnormality and clastogenic potential of cypermethrin

Adult male Swiss albino mice were administered ip. suspension solution of cypermethrin in 0.15% DMSO at the doses of 30 mg, 60 mg and 90 mg/kg b. wt. daily for 5 days. Another group of animals was injected cyclophosphamide ip. (60 mg/kg b. wt.) in similar manner which served as positive control. Effect of cypermethrin on body and testes weight and sperm head morphology was studied. Clastogenic potential of cypermethrin was studied by using modified Allium test. The cytological changes were studied in the root tip cells of Allium cepa after 3 days treatment with three different concentration of cypermethrin (0.1, 1.0 and 10.0 microg/ml). The results revealed that body weight gain was considerably reduced in higher dose groups, but the testicular weight did not change significantly in any of the cypermethrin treated groups. However, a significant elevation in the number of abnormal shape of sperm head was noticed in higher dose groups as compared to control. It was observed that the abnormality in the shape of sperm head was dose-dependent. The cytological changes in the root tip cells of Allium cepa indicated that cypermethrin is having toxic effects on the root tip cells in the form of stickiness of chromosomes and also affect the mitotic activity. This study suggest that cypermethrin may have the potential to induce adverse effects on sperm head shape morphology of mouse as well as clastogenic effects on root tip cells of Allium cepa.