The inducible and cytochrome P450-containing dehydroepiandrosterone 7α-hydroxylating enzyme system of Fusarium moniliforme

7α-Hydroxylation of DHEA by Fusarium moniliforme was investigated with regard to inducibility and characterization of the responsible enzyme system. Using GC/MS, the 7-hydroxylated metabolites of DHEA produced after biotransformation by Fusarium moniliforme mycelia were identified. The strain of Fusarium moniliforme hydroxylated DHEA predominantly at the 7α-position, with minor hydroxylation occurring at the 7β-position. Constitutive 7α-hydroxylation activity was low, but DHEA induced the enzyme complex responsible for 7α-hydroxylation via an increase in protein synthesis. DHEA 7α-hydroxylase was found to be mainly microsomal, and the best production yields of 7α-hydroxy-DHEA (28.5 ± 3.51 pmol/min/mg protein) were obtained with microsomes prepared from 18-h-induced mycelia. Kinetic parameters (K_M=1.18 ± 0.035 μM and V_max=909 ± 27 pmol/min/mg protein) were determined. Carbon monoxide inhibited 7α-hydroxylation of DHEA by microsomes of Fusarium moniliforme. Also, exposure of mycelia to DHEA increased microsomal P450 content. These results demonstrated that: (i) DHEA is 7α-hydroxylated by microsomes of Fusarium moniliforme; (ii) DHEA induces Fusarium moniliforme 7α-hydroxylase; (iii) this enzyme complex contains a cytochrome P450.     

Calcitonin administration improves endometrial receptivity via regulation of LIF,Muc-1 and microRNA Let-7a in mice

Calcitonin (CT) is one of the factors affecting the embryo implantation, but its effects on the implantation window have not been fully investigated. The current study investigated the effects of CT on the endometrium receptivity by morphological study and evaluation of leukemia inhibitory factor (LIF), mucin 1 (Muc-1), and microRNA (miRNA) Let-7a in the ovarian stimulation and the normal ovarian cycle. Then the mechanism of the CT effects through the mammalian target of rapamycin (mTOR) signaling pathway was studied by using PP242. A total of 64 BALB/c mice were divided into the normal ovarian cycle and ovarian stimulation groups. Each group consisted of four subgroups: control, calcitonin, PP242, and calcitonin+PP242. CT and PP242 were injected on the fourth of pregnancy into the mice and 24 hr later all the mice were killed. The uterine tissue samples were used for morphological analysis, and endometrial cells were mechanically isolated for evaluation of gene and protein expression. The results showed that ovarian stimulation induced mTOR phosphorylation as well as increased expression of the Let-7a miRNA. In addition, CT injection increased the expression of LIF and miRNA Let-7a in ovarian stimulation similar to that in normal ovarian cycles. However, injection of PP242 reduced expression of miRNA Let-7a and increased Muc-1 expression in ovarian stimulation group. In conclusion, the administration of CT improved endometrial receptivity in mice. This phenomenon occurred by upregulation of LIF, miRNA Let-7a and downregulation of Muc-1 via mTOR signaling pathway.     

Development of α4 integrin DNA aptamer as a potential therapeutic tool for multiple sclerosis

One of the most important molecules for multiple sclerosis pathogenesis is α4 integrin, which is responsible for autoreactive leukocytes migration into the brain. The monoclonal antibody, natalizumab, was introduced to market for blocking the extravasation of autoreactive leukocytes via inhibition of α4 integrin. However, the disadvantages of antibodies provided a suitable background for other agents to be replaced with antibodies. Considering the profound advantages of aptamers over antibodies, aptamer isolation against α4 integrin was intended in the current study. The α4 integrin-specific aptamers were selected using cell-systematic evolution of ligands by exponential enrichment (SELEX) method with human embryonic kidney (HEK)-293T overexpressing α4 integrin and HEK-293T as target and control cells, respectively. Evaluation of selected aptamer was performed through flow cytometric analysis. The selected clones were then sequenced and analyzed for any possible secondary structure and affinity. The results of this study led to isolation of 13 different single-stranded DNA clones in 11 rounds of selection which were categorized to three clusters based on common structural motifs and the equilibrium dissociation constant (K _d) of the most stable structure was calculated. The evaluation of SELEX progress showed growth in aptamer affinity with increasing of the number of cycles. Taken together, the findings of this study demonstrated the isolation of α4-specific single-stranded DNA aptamers with suitable affinity for ligand, which can further be replaced with natalizumab.     

Degradation of dibutyl phthalate by Paenarthrobacter sp. Shss isolated from Saravan landfill,Hyrcanian Forests,Iran

Biodegradation - Phthalic acid esters are predominantly used as plasticizers and are industrially produced on the million ton scale per year. They exhibit endocrine-disrupting, carcinogenic,...     

Novel strategies for inhibition of bacterial biofilm in chronic rhinosinusitis

An important role has been recently reported for bacterial biofilm in the pathophysiology of chronic diseases, such as chronic rhinosinusitis (CRS). CRS, affecting sinonasal mucosa, is a persistent inflammatory condition with a high prevalence around the world. Although the exact pathological mechanism of this disease has not been elicited yet, biofilm formation is known to lead to a more significant symptom burden and major objective clinical indicators. The high prevalence of multidrug-resistant bacteria has severely restricted the application of antibiotics in recent years. Furthermore, systemic antibiotic therapy, on top of its insufficient concentration to eradicate bacteria in the sinonasal biofilm, often causes toxicity, antibiotic resistance, and an effect on the natural microbiota, in patients. Thus, coming up with alternative therapeutic options instead of systemic antibiotic therapy is emphasized in the treatment of bacterial biofilm in CRS patients. The use of topical antibiotic therapy and antibiotic eluting sinus stents that induce higher antibiotic concentration, and decrease side effects could be helpful. Besides, recent research recognized that various natural products, nitric oxide, and bacteriophage therapy, in addition to the hindered biofilm formation, could degrade the established bacterial biofilm. However, despite these improvements, new antibacterial agents and CRS biofilm interactions are complicated and need extensive research. Finally, most studies were performed in vitro, and more preclinical animal models and human studies are required to confirm the collected data. The present review is specifically discussing potential therapeutic strategies for the treatment of bacterial biofilm in CRS patients.     

In vivo respiratory metabolism of illuminated leaves

Day respiration of illuminated C(3) leaves is not well understood and particularly, the metabolic origin of the day respiratory CO(2) production is poorly known. This issue was addressed in leaves of French bean (Phaseolus vulgaris) using (12)C/(13)C stable isotope techniques on illuminated leaves fed with (13)C-enriched glucose or pyruvate. The (13)CO(2) production in light was measured using the deviation of the photosynthetic carbon isotope discrimination induced by the decarboxylation of the (13)C-enriched compounds. Using different positional (13)C-enrichments, it is shown that the Krebs cycle is reduced by 95% in the light and that the pyruvate dehydrogenase reaction is much less reduced, by 27% or less. Glucose molecules are scarcely metabolized to liberate CO(2) in the light, simply suggesting that they can rarely enter glycolysis. Nuclear magnetic resonance analysis confirmed this view; when leaves are fed with (13)C-glucose, leaf sucrose and glucose represent nearly 90% of the leaf (13)C content, demonstrating that glucose is mainly directed to sucrose synthesis. Taken together, these data indicate that several metabolic down-regulations (glycolysis, Krebs cycle) accompany the light/dark transition and emphasize the decrease of the Krebs cycle decarboxylations as a metabolic basis of the light-dependent inhibition of mitochondrial respiration.     

Hyperprolactinemia after laparoscopic ovarian drilling: An unknown phenomenon

Background  

The effects of ovarian drilling on the serum levels of gonadotropins and androgens have been studied previously. The aim of this study is to evaluate the effects of ovarian drilling on the serum prolactin levels and its relation to ovulation in women with polycystic ovary syndrome.     

Heterologous virus-induced gene silencing as a promising approach in plant functional genomics

VIGS (virus induced gene silencing) is considered as a powerful genomics tool for characterizing the function of genes in a few closely related plant species. The investigations have been carried out mainly in order to test if a pre-existing VIGS vector can serve as an efficient tool for gene silencing in a diverse array of plant species. Another route of investigation has been the constructing of new viral vectors to act in their hosts. Our approach was the creation of a heterologous system in which silencing of endogenous genes was achieved by sequences isolated from evolutionary remote species. In this study, we showed that a TRV-based vector cloned with sequences from a gymnosperm, Taxus baccata L. silenced the endogenous phytoene desaturase in an angiosperm, N. benthamiana. Our results showed that inserts of between 390 and 724 bp isolated from a conserved fragment of the Taxus PDS led to silencing of its homolog in tobacco. The real time analysis indicated that the expression of PDS was reduced 2.1- to 4.0-fold in pTRV-TbPDS infected plants compared with buffer treated plants. Once the best insert is identified and the conditions are optimized for heterologous silencing by pTRV-TbPDS in tobacco, then we can test if TRV can serve as an efficient silencing vector in Taxus. This strategy could also be used to silence a diverse array of genes from a wide range of species which have no VIGS protocol. The results also showed that plants silenced heterologously by the VIGS system a minimally affected with respect to plant growth which may be ideal for studying the genes that their complete loss of function may lead to decrease of plant growth or plant death.     

A multi-stage model for fundamental functional properties in primary visual cortex

Many neurons in mammalian primary visual cortex have properties such as sharp tuning for contour orientation, strong selectivity for motion direction, and insensitivity to stimulus polarity, that are not shared with their sub-cortical counterparts. Successful models have been developed for a number of these properties but in one case, direction selectivity, there is no consensus about underlying mechanisms. We here define a model that accounts for many of the empirical observations concerning direction selectivity. The model describes a single column of cat primary visual cortex and comprises a series of processing stages. Each neuron in the first cortical stage receives input from a small number of on-centre and off-centre relay cells in the lateral geniculate nucleus. Consistent with recent physiological evidence, the off-centre inputs to cortex precede the on-centre inputs by a small (～4 ms) interval, and it is this difference that confers direction selectivity on model neurons. We show that the resulting model successfully matches the following empirical data: the proportion of cells that are direction selective; tilted spatiotemporal receptive fields; phase advance in the response to a stationary contrast-reversing grating stepped across the receptive field. The model also accounts for several other fundamental properties. Receptive fields have elongated subregions, orientation selectivity is strong, and the distribution of orientation tuning bandwidth across neurons is similar to that seen in the laboratory. Finally, neurons in the first stage have properties corresponding to simple cells, and more complex-like cells emerge in later stages. The results therefore show that a simple feed-forward model can account for a number of the fundamental properties of primary visual cortex.