Alterations in Neurotransmitter Receptor Binding in Discrete Areas of the Copper-Deficient Rat Brain

Abstract: Neonatal copper deficiency produced alterations in central neurotransmitter receptors that were selective with respect both to brain region and to neurotransmitter receptor type. Both high- and low-affinity dopamine receptor densities in the corpus striatum were significantly lowered, 55% and 29%, respectively, when expressed on a wet weight basis. There was a significant decrease in the level of muscarinic receptors in the striatum whether expressed on the basis of wet weight (50%) or protein (27%). A smaller reduction in muscarinic receptor density was observed in the cortex, whereas there was no effect of copper deficiency in the cerebellum. The treatment did not change β-adrenergic receptor binding in either the cortex or cerebellum. The affinities of the receptors for the ligands was not affected by the low-copper diet. It was previously reported that copper deficiency produces regionally specific decreases in the concentrations of dopamine and norepinephrine. The greatest reduction occurred in the concentration of dopamine in the corpus striatum. The results from both studies suggest that copper deficiency in post-weanling rats may induce a selective morphological lesion.     

Variety-specific response of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) leaf mitochondria to drought stress

The main objective of the present work was to examine leaf respiratory responses to dehydration and subsequent recovery in three varieties of winter wheat (Triticum aestivum L.) known to differ in their level of drought tolerance. Under dehydration, both total respiration and salicylhydroxamic acid (SHAM)-resistant cytochrome (Cyt) pathway respiration by leaf segments decreased significantly compared with well-watered plants. This decrease was more pronounced in the drought-sensitive Sadovo and Prelom genotypes. In contrast, the KCN-resistant SHAM-sensitive alternative (Alt) pathway became increasingly engaged, and accounted for about 80% of the total respiration. In the drought-tolerant Katya variety, increased contribution of the Alt pathway was accompanied by a slight decrease in Cyt pathway activity. Respiration of isolated leaf mitochondria also showed a variety-specific drought response. Mitochondria from drought-sensitive genotypes had low oxidative phosphorylation efficiency after dehydration and rewatering, whereas the drought-tolerant Katya mitochondria showed higher phosphorylation rates. Morphometric analysis of leaf ultrastructure revealed that mitochondria occupied approximately 7% of the cell area in control plants. Under dehydration, in the drought-sensitive varieties this area was reduced to about 2.0%, whereas in Katya it was around 6.0%. The results are discussed in terms of possible mechanisms underlying variety-specific mitochondrial responses to dehydration.     

Pattern formation in auxin flux

The plant hormone auxin is fundamental for plant growth, and its spatial distribution in plant tissues is critical for plant morphogenesis. We consider a leading model of the polar auxin flux, and study in full detail the stability of the possible equilibrium configurations. We show that the critical states of the auxin transport process are composed of basic building blocks, which are isolated in a background of auxin depleted cells, and are not geometrically regular in general. The same model was considered recently through a continuous limit and a coupling to the von Karman equations, to model the interplay of biochemistry and mechanics during plant growth. Our conclusions might be of interest in this setting, since, for example, we establish the existence of Lyapunov functions for the auxin flux, proving in this way the convergence of pure transport processes toward the set of equilibrium points.     

Expression of γ-H2AX and patient prognosis in breast cancer cohort

H2AX phosphorylation is a novel marker of DNA double-stranded breaks. In the present study, we assessed the γ-H2AX expression, its association with other clinicopathologic characteristics, and the prognosis in a cohort of 97 patients with breast cancer. Ninety-seven specimens of tumor tissue and 77 adjacent normal tissues from patients with breast cancer were examined. All patients underwent modified radical mastectomy or local tumor resection without lymph node dissection. γ-H2AX expression was assessed by standard immunohistochemistry. Patients were followed after surgery for a mean duration of 70.1 ± 18.7 months (range, 6-93 months). The γ-H2AX staining was positive in 27 (27.8%) patients. The positive rates of H2AX were 26.0% and 2.6% in tumor tissue and adjacent normal tissues, respectively. γ-H2AX positive status was negatively associated with TNM staging, with 24 positive cases (32.4%) in TNM staging I-II, while no positive cases in TNM staging III-IV (P = 0.026). Sixteen patients (16.5%) died during the follow-up. No significant association between γ-H2AX expression and patient survival was detected. The unadjusted HR (hazard ratio) for γ-H2AX positive was 0.84 (95% CI: 0.27, 2.60). In TNM staging subgroup analysis, death only occurred in γ-H2AX negative patients. Our study is the first study to demonstrate that expression of γ-H2AX is associated with TNM staging. Due to the small sample and limited follow-up time, we did not observe a significant association between γ-H2AX and patient survival. γ-H2AX expression could be a potential biomarker for cancer diagnosis and prediction, and further studies are in need.