Embryonic development of the tree frog, Hyla arborea

A staged series with time data and original photographs of the embryonic development of the tree frog, Hyla arborea are presented, following Gosner’s generalized table. To contribute to species specific embryological studies of anurans, the external features of development of this species were described. Duration of embryonic development, from fertilization to 25^th stage, is about 9 days at 20 ± 1 °C. Cleavage is holoblastic and unequal. Unlike the typical anuran development, neurular rotation was not observed in stage 15 or in any other stages. Other developmental stages resulted in a normal-looking. Embryos of H. arborea hatched at stage 20 or 21, which varied individually. Hatching occurred in the 4^th or 5^th day after fertilization. The mean total length of hatchlings was calculated as 6.38 mm. The mean size of ovum was estimated 1.4 mm in diameter.     

Grouping and Crowding Affect Target Appearance over Different Spatial Scales

Crowding is the impairment of peripheral target perception by nearby flankers. A number of recent studies have shown that crowding shares many features with grouping. Here, we investigate whether effects of crowding and grouping on target perception are related by asking whether they operate over the same spatial scale. A target letter T had two sets of flanking Ts of varying orientations. The first set was presented close to the target, yielding strong crowding. The second set was either close enough to cause crowding on their own or too far to cause crowding on their own. The Ts of the second set had the same orientation that either matched the target’s orientation (Grouped condition) or not (Ungrouped condition). In Experiment 1, the Grouped flankers reduced crowding independently of their distance from the target, suggesting that grouping operated over larger distances than crowding. In Experiments 2 and 3 we found that grouping did not affect sensitivity but produced a strong bias to report that the grouped orientation was present at the target location whether or not it was. Finally, we investigated whether this bias was a response or perceptual bias, rejecting the former in favor of a perceptual grouping explanation. We suggest that the effect of grouping is to assimilate the target to the identity of surrounding flankers when they are all the same, and that this shape assimilation effect differs in its spatial scale from the integration effect of crowding.     

Platelet-Derived Growth Factor CC-Mediated Neuroprotection against HIV Tat Involves TRPC-Mediated Inactivation of GSK 3beta

Platelet-derived growth factor-CC (PDGF-CC) is the third member of the PDGF family, and has been implicated both in embryogenesis and development of the CNS. The biological function of this isoform however, remains largely unexplored in the context of HIV-associated dementia (HAD). In the present study, we demonstrate that exposure of human neuroblastoma cells SH-SY5Y to HIV transactivator protein Tat resulted in decreased intrinsic expression of PDGF-CC as evidenced by RT-PCR and western blot assays. Reciprocally, pretreatment of SH-SY5Y cells with PDGF-CC abrogated Tat-mediated neurotoxicity by mitigating apoptosis and neurite & MAP-2 loss. Using pharmacological and loss of function approaches we identified the role of phosphatidylinositol 3-kinase (PI3K)/Akt signaling in PDGF-CC-mediated neuroprotection. We report herein a novel role about the involvement of transient receptor potential canonical (TRPC) channel 1 in modulation of calcium transients in PDGF-CC-mediated neuroprotection. Furthermore we also demonstrated PDGF-CC-mediated inactivation of the downstream mediator - glycogen synthase kinase 3β (GSK3β) evidenced by its phosphorylation at Ser-9. This was further validated by gain and loss of function studies using cells transfected with either the wild type or mutant GSK3β constructs. Intriguingly, pretreatment of cells with either the PI3K inhibitor or TRPC blocker resulted in failure of PDGF-CC to inactivate GSK3β, thereby suggesting the intersection of PI3K and TRPC signaling at GSK3β. Taken together our findings lead to the suggestion that PDGF-CC could be developed as a therapeutic target to reverse Tat-mediated neurotoxicity with implications for HAD.     

Antibiotic and heavy metal resistance in Gram-negative bacteria isolated from the Seyhan Dam Lake and Seyhan River in Turkey

This study aimed to determine the pattern of antibiotic and heavy metal resistance in Gram-negative bacteria isolated from five different sites in the Seyhan Dam Lake and Seyhan River in Adana, Turkey. The susceptibility of 268 isolates to 16 different antibiotics and five heavy metals was investigated by agar diffusion and dilution methods, respectively. The most common species isolated from the samples were Aeromonas hydrophila (17.5 %), Aeromonas caviae (8.9 %) and Citrobacter freundii (8.9 %). There was a high incidence of resistance to ampicillin (80.2 %), streptomycin (71.6 %) and cefazolin (60.4 %). Multiple antibiotic resistance indices ranged from 0.2 to 0.81, suggesting exposure to antibiotic contamination. The isolates showed tolerance to different concentrations of heavy metals. These results indicate that antibiotic and heavy metal resistance among the Seyhan Dam Lake and Seyhan River bacteria may pose a risk to the fish population and public health. At the same time, the finding in the aquatic environments of different combinations of resistance genes suggests their involvement in the spread of multidrug-resistant strains.     

Lithium-induced renal toxicity in rats: Protection by a novel antioxidant caffeic acid phenethyl ester

Lithium carbonate used in the long-term treatment of manic-depressive illness has been reported to lead to progressive renal impairment in rats and humans. Caffeic acid phenethyl ester (CAPE), a component of honeybee propolis, protects tissues from reactive oxygene species mediated oxidative stress in ischemia-reperfusion and toxic injuries. The beneficial effect CAPE on lithium-induced nephrotoxicity has not been reported yet. The purpose of this study was to examine a possible renoprotective effect of CAPE against lithium-induced nephrotoxicity in a rat model. Twenty-two adult male rats were randomly divided into three experimental groups, as follows: control group, lithium-treated group (Li), and lithium plus CAPE-treated group (Li+CAPE). Li were treated intraperitoneally (i.p.) with 25 mg/kg Li₂CO₃ solution in 0.9% NaCl twice daily for 4 weeks. CAPE was co-administered i.p. with a dose of 10 μM/kg/day for 4 weeks. Serum Li, blood urea nitrogen and plasma creatinine, urinary N-acetyl-β-D-glucosaminidase (NAG, a marker of renal tubular injury), and malondialdehyde (MDA, an index of lipid peroxidation), were used as markers of oxidative stress-induced renal impairment in Li-treated rats. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were studied to evaluate the changes of antioxidant status in renal tissue. Serum Li levels were found high in the Li and Li+CAPE groups. In Li-administrated rats, urinary NAG and renal MDA levels were increased according to control and Li+CAPE groups (p < 0.05). CAPE caused a significant reduction in the levels of these parameters. Likewise, renal SOD, CAT and GSH-Px activities were decreased in Li-administrated animals; CAPE caused a significant increase in the activities of these antioxidant enzymes. In conclusion, CAPE treatment has a protective effect against Li-induced renal tubular damage and oxidative stress in a rat model.     

The effects of diazinon on lipid peroxidation and antioxidant enzymes in rat heart and ameliorating role of vitamin E and vitamin C

Diazinon is one of the most widely used organophosphate insecticides (OPIs) in agriculture and public health programs. Reactive oxygen species (ROS) caused by OPIs may be involved in the toxicity of various pesticides. The aim of this study was to investigate how diazinon affects lipid peroxidation (LPO) and the antioxidant defense system in vivo and the possible ameliorating role of vitamins E and C. For this purpose, experiments were done to study the effects of DI on LPO and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in adult rat heart. Experimental groups were: (1) control group, (2) diazinon treated (DI) group, (3) DI+vitamins E and C-treated (DI+Vit) group. The levels of malondialdehyde (MDA) and the activities of SOD and CAT increased significantly in the DI group compared with the control group. The activity of SOD and the levels of MDA decreased significantly in the DI+Vit group compared with the DI group. The differences between the DI+Vit and control groups according to the MDA levels and the activities of both SOD and CAT were statistically significant. These results suggest that treating rats with a single dose of diazinon increases LPO and some antioxidant enzyme activities in the rat myocardium and, in addition, that single-dose treatment with a combination of vitamins E and C after the administration of diazinon can reduce LPO caused by diazinon, though this treatment was not sufficiently effective to reduce the values to those in control group.     

Na+/I− Symporter and Type 3 Iodothyronine Deiodinase Gene Expression in Amniotic Membrane and Placenta and Its Relationship to Maternal Thyroid Hormones

Placental type 3 iodothyronine deiodinase (D3) potentially protects the fetus from the elevated maternal thyroid hormones. Na⁺/I^? symporter (NIS) is a plasma membrane glycoprotein, which mediates active iodide uptake. Our objectives were to establish the distribution of NIS and D3 gene expressions in the placenta and the amniotic membrane and to investigate the relationship between placental D3 and NIS gene expressions and maternal iodine, selenium, and thyroid hormone status. Thyroid hormones, urinary iodine concentration (UIC), and selenium levels were measured in 49 healthy term pregnant women. NIS and D3 gene expressions were studied with the total mRNA RT-PCR method in tissues from maternal placenta (n?=?49), fetal placenta (n?=?9), and amniotic membrane (n?=?9). NIS and D3 gene expressions were shown in the fetal and maternal sides of the placenta and amniotic membrane. Mean blood selenium level was 66?±?26.5 μg/l, and median UIC was 143 μg/l. We could not demonstrate any statistically significant relationship of spot UIC and blood selenium with NIS and D3 expression (p?>?0.05). Positive correlations were found between NIS and thyroxine-binding globulin (TBG) (r?=?0.3, p?=?0.042) and between D3 and preoperative glucose levels (r?=?0.4, p?=?0.006). D3 and NIS genes are expressed in term placenta and amniotic membrane; thus, in addition to placenta, amniotic membrane contributes to regulation of maternofetal iodine and thyroid hormone transmission. Further studies are needed to clarify the relationship between maternal glucose levels and placental D3 expression and between TBG and placental NIS expression.