The Himalayas: Barrier and conduit for gene flow

The Himalayan mountain range is strategically located at the crossroads of the major cultural centers in Asia, the Middle East and Europe. Although previous Y‐chromosome studies indicate that the Himalayas served as a natural barrier for gene flow from the south to the Tibetan plateau, this region is believed to have played an important role as a corridor for human migrations between East and West Eurasia along the ancient Silk Road. To evaluate the effects of the Himalayan mountain range in shaping the maternal lineages of populations residing on either side of the cordillera, we analyzed mitochondrial DNA variation in 344 samples from three Nepalese collections (Newar, Kathmandu and Tamang) and a general population of Tibet. Our results revealed a predominantly East Asian‐specific component in Tibet and Tamang, whereas Newar and Kathmandu are both characterized by a combination of East and South Central Asian lineages. Interestingly, Newar and Kathmandu harbor several deep‐rooted Indian lineages, including M2, R5, and U2, whose coalescent times from this study (U2, >40 kya) and previous reports (M2 and R5, >50 kya) suggest that Nepal was inhabited during the initial peopling of South Central Asia. Comparisons with our previous Y‐chromosome data indicate sex‐biased migrations in Tamang and a founder effect and/or genetic drift in Tamang and Newar. Altogether, our results confirm that while the Himalayas acted as a geographic barrier for human movement from the Indian subcontinent to the Tibetan highland, it also served as a conduit for gene flow between Central and East Asia. Am J Phys Anthropol 151:169–182, 2013. © 2013 Wiley Periodicals, Inc.     

The Microbiome of the Red Sea Coral Stylophora pistillata Is Dominated by Tissue-Associated Endozoicomonas Bacteria

Endozoicomonas bacteria were found highly associated with the coral Stylophora pistillata, and these bacteria are also ubiquitously associated with diverse corals worldwide. Novel Endozoicomonas-specific probes revealed that Endozoicomonas bacteria were abundant in the endodermal tissues of S. pistillata and appear to have an intimate relationship with the coral.     

Biomarkers of clinical responsiveness in brain tumor patients : progress and potential

Gliomas are the most common primary brain tumors in adults. Anaplastic astrocytoma and glioblastoma multiforme represent malignant astrocytomas, which are the most common type of malignant gliomas. Despite research efforts in cancer therapy, the prognosis of patients with malignant gliomas remains poor. Research efforts in recent years have focused on investigating the cellular, molecular, and genetic pathways involved in the progression of malignant gliomas. As a result, biomarkers have emerged as diagnostic, predictive, and prognostic tools that have the potential to transform the field of brain tumor diagnostics. An increased understanding of the important molecular pathways that have been implicated in the progression of malignant gliomas has led to the identification of potential diagnostic, prognostic, and predictive biomarkers, some bearing clinical implications for targeted therapy. Some of the most promising biomarkers to date include loss of chromosomes 1p/19q in oligodendrogliomas and expression of O-6-methylguanine-DNA methyltransferase (MGMT) or epidermal growth factor receptor (EGFR) status in glioblastomas. Other promising biomarkers in glioma research include glial fibrillary acidic protein, galectins, Kir potassium channel proteins, angiogenesis, and apoptosis pathway markers. Research into the clinical relevance and applicability of such biomarkers has the potential to revolutionize our approach to the diagnosis and treatment of patients with malignant gliomas.     

Synthesis and biological evaluation of 2-amino-7,7-dimethyl 4-substituted-5-oxo-1-(3,4,5-trimethoxy)-1,4,5,6,7,8-hexahydro-quinoline-3-carbonitrile derivatives as potential cytotoxic agents

A large number of antimitotic drugs, derived from natural sources or chemically synthesized, have been identified and shown to interfere with the tubulin system. Inhibition of tubulin polymerization is among the important targets useful in the cancer therapy.The present work reports the synthesis of some novel quinoline derivatives bearing a trimethoxyphenyl moiety. The trimethoxybenzene moiety has been reported to be crucial to obtain relevant cytotoxic and antitubulin responses. All the newly synthesized compounds were evaluated for their in vitro anticancer activity. Several compounds showed interesting cytotoxic activities compared to the used reference drug.     

Comparison of the Arylamine <Emphasis Type="Italic">N-</Emphasis>Acetyltransferase from <Emphasis Type="Italic">Mycobacterium marinum</Emphasis> and <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis>

Arylamine N-acetyltansferase (NAT) from Mycobacterium tuberculosis (TBNAT) is a potential drug target for anti-tubercular therapy. Recombinant TBNAT is much less soluble and is produced in lower yields than the closely related NAT from Mycobacterium marinum (MMNAT). In order to explore MMNAT as a model for TBNAT in drug discovery, we compare the two mycobacterial NAT enzymes. Two site-directed mutants of MMNAT have been prepared and characterised: MMNAT71, Tyr → Phe and MMNAT209, Met → Thr, in which residues within 6 Å of the active-site cysteine have been replaced with the corresponding residue from TBNAT. Two chimeric proteins have also been produced in which the third domain of MMNAT has been replaced by the third domain of TBNAT and vice versa. The activity profile of the chimeric proteins suggests a role for the third domain in the evolutionary divergence of NAT between these closely related mycobacterial species.     

Novel KRAS Gene Mutations in Sporadic Colorectal Cancer

Introduction

In this article, we report 7 novel KRAS gene mutations discovered while retrospectively studying the prevalence and pattern of KRAS mutations in cancerous tissue obtained from 56 Saudi sporadic colorectal cancer patients from the Eastern Province.

Methods

Genomic DNA was extracted from formalin-fixed, paraffin-embedded cancerous and noncancerous colorectal tissues. Successful and specific PCR products were then bi-directionally sequenced to detect exon 4 mutations while Mutector II Detection Kits were used for identifying mutations in codons 12, 13 and 61. The functional impact of the novel mutations was assessed using bioinformatics tools and molecular modeling.

Results

KRAS gene mutations were detected in the cancer tissue of 24 cases (42.85%). Of these, 11 had exon 4 mutations (19.64%). They harbored 8 different mutations all of which except two altered the KRAS protein amino acid sequence and all except one were novel as revealed by COSMIC database. The detected novel mutations were found to be somatic. One mutation is predicted to be benign. The remaining mutations are predicted to cause substantial changes in the protein structure. Of these, the Q150X nonsense mutation is the second truncating mutation to be reported in colorectal cancer in the literature.

Conclusions

Our discovery of novel exon 4 KRAS mutations that are, so far, unique to Saudi colorectal cancer patients may be attributed to environmental factors and/or racial/ethnic variations due to genetic differences. Alternatively, it may be related to paucity of clinical studies on mutations other than those in codons 12, 13, 61 and 146. Further KRAS testing on a large number of patients of various ethnicities, particularly beyond the most common hotspot alleles in exons 2 and 3 is needed to assess the prevalence and explore the exact prognostic and predictive significance of the discovered novel mutations as well as their possible role in colorectal carcinogenesis.     

A threshold level of TLR9 mRNA predicts cellular responsiveness to CpG-ODN in haematological and non-haematological tumour cell lines

The human toll like receptor 9 (TLR9) detects differences between microbial and host DNA, based on unmethylated deoxycytidyl deoxyguanosine dinucleotide (CpG) motifs, leading to activation of both innate and adaptive immune mechanisms. The synthetic TLR9 agonist, CpG-ODN, can substitute for microbial DNA in these responses, and is in clinical trials as an immunomodulatory agent in diseases as diverse as infections, cancer and allergic disorders. Human TLR9 is expressed on cells of haematopoietic origin (principally plasmacytoid dendritic cells and B cells), but has also been described as being expressed on a number of other cell types. In order to clarify the expression and function of TLR9 in a range of cells of both haematopoietic and non-haematopoietic origin, we investigated the level of expression of TLR9 mRNA, and the ability of the cells to respond to CpG-ODN by upregulation of cell surface markers, cytokine production, cellular proliferation and activation of NFκB. Our data show that the cellular response to CpG-ODN depended on a threshold level of expression of TLR9. TLR9 was widely expressed amongst B cell tumours (with the exception of myeloma cell lines), but we did not find either threshold levels of expression of TLR9 or responses to CpG-ODN in several myeloma or myeloid tumour cell lines or any non-haematological tumour cell lines tested in our study. TLR9-positive cells varied significantly in their responses to CpG-ODN, and the level of TLR9 expression beyond the threshold did not correlate with the magnitude of the response to CpG-ODN. Finally, CpG-ODN induced NFκB activation and increased cellular proliferation in Hek293 cells that had been stably transfected with hTLR9, but did not affect the expression of surface markers or synthesis of IL-6, IL-10 or TNF-α. Thus both haematological and non-haematological cells expressing appropriate levels of TLR9 respond to CpG-ODN, but the nature of the TLR9-mediated response is dependent on cell type.     

Paternal bisphenol A exposure induces testis and sperm pathologies in mice offspring: Possibly due to oxidative stress?

Bisphenol A (BPA), an endocrine and metabolic disruptor, is widely used to manufacture polycarbonate plastics and epoxy resins. Accumulating evidence suggests that paternal BPA exposure adversely affects male germlines and results in atypical reproductive phenotypes that might persist for generations to come. Our study investigated this exposure on testicular architecture and sperm quality in mouse offspring, and characterised underlying molecular mechanism(s). A total of 18 immature male Swiss albino mice (3.5 weeks old) were randomly divided into three groups and treated as follows: Group I, no treatment (sham control); Group II, sterile corn oil only (vehicle control); Group III, BPA (400 μg/kg) in sterile corn oil. At 9.5 weeks old, F0 males were mated with unexposed females. F0 offspring (F1 generation) were monitored for postnatal development for 10 weeks. At 11.5 weeks old, the animals were sacrificed to examine testicular architecture, sperm parameters, including DNA integrity, and oxidative stress biomarkers. Results showed that BPA significantly induced changes in the body and testis weights of the F0 and F1 generation BPA lineages compared to F0 and F1 generation control lineages. A decrease in sperm count and motility with further, increased sperm abnormalities, no or few sperm DNA alterations and elevated levels of MDA, PC and NO were recorded. Similar effects were found in BPA exposed F0 males, but were more pronounced in the F0 offspring. In addition, BPA caused alterations in the testicular architecture. These pathological changes extended transgenerationally to F1 generation males’ mice, but the pathological changes were more pronounced in the F1 generation. Our findings demonstrate that the biological and health BPA impacts do not end in paternal adults, but are passed on to offspring generations. Hence, linking observed testis and sperm abnormalities in the F1 generation to BPA exposure of their parental line was evident in this work. The findings also illustrate that oxidative stress appears to be a molecular component of the testis and sperm pathologies.     

A steroid isolated from the water mold Achlya heterosexualis induces neurogenesis in vitro and in vivo

Using 22R-hydroxycholesterol as a sub-structure to screen natural compound databases, we identified a naturally occurring steroid (sc-7) with a 16-acetoxy-22R-hydroxycholesterol moiety, in which the hydroxyl groups in positions 3 and 22 are esterified by an acetoxy group and in which the carbon in position 26 carries a functional diacetylamino. sc-7 is an analog of the sex steroids dehydro-oogoniol and antheridiol, can be isolated from the water mold Achlya heterosexualis, and promoted neurogenesis in vitro and in vivo. Mouse embryonic teratocarcinoma P19 cells exposed to sc-7 for 2days followed by a 5-day wash-out differentiated into cholinergic neurons that expressed specific neuronal markers and displayed axonal formation. Axons continued growing up to 28days after treatment. In vivo, infusion of sc-7 for 2weeks into the left ventricle of the rat brain followed by a 3-week wash-out induced bromodeoxyuridine uptake by cells of the ependymal layer and subventricular zone that co-localized with doublecortin and glial fibrillary acidic protein immunostaining, demonstrating induction of proliferation and differentiation of neuronal progenitors. Migrating neuroblasts were also observed in the corpus callosum. Thus, under these experimental conditions, adult ependymal cells resumed proliferation and differentiation. Taken together, these results suggest that sc-7 is an interesting molecule for stimulating in situ neurogenesis from resident neuronal progenitors as part of neuron replacement therapy. sc-7 did not bind to nuclear steroid receptors and was not metabolized as a steroid, supporting our hypothesis that the neurogenic effect of sc-7 is not likely due to a steroid-like effect.