Matrix Metalloproteinase (MMP) Proteolysis of the Extracellular Loop of Voltage-gated Sodium Channels and Potential Alterations in Pain Signaling

Congenital insensitivity to pain (CIP) or congenital analgesia is a rare monogenic hereditary condition. This disorder is characterized by the inability to perceive any form of pain. Nonsense mutations in Nav.1.7, the main pain signaling voltage-gated sodium channel, lead to its truncations and, consequently, to the inactivation of the channel functionality. However, a non-truncating homozygously inherited missense mutation in a Bedouin family with CIP (Nav1.7-R907Q) has also been reported. Based on our currently acquired in-depth knowledge of matrix metalloproteinase (MMP) cleavage preferences, we developed the specialized software that predicts the presence of the MMP cleavage sites in the peptide sequences. According to our in silico predictions, the peptide sequence of the exposed extracellular unstructured region linking the S5–S6 transmembrane segments in the DII domain of the human Nav1.7 sodium channel is highly sensitive to MMP-9 proteolysis. Intriguingly, the CIP R907Q mutation overlaps with the predicted MMP-9 cleavage site sequence. Using MMP-9 proteolysis of the wild-type, CIP, and control peptides followed by mass spectrometry of the digests, we demonstrated that the mutant sequence is severalfold more sensitive to MMP-9 proteolysis relative to the wild type. Because of the substantial level of sequence homology among sodium channels, our data also implicate MMP proteolysis in regulating the cell surface levels of the Nav1.7, Nav1.6, and Nav1.8 channels, but not Nav1.9. It is likely that the aberrantly accelerated MMP-9 proteolysis during neurogenesis is a biochemical rational for the functional inactivation in Nav1.7 and that the enhanced cleavage of the Nav1.7-R907Q mutant is a cause of CIP in the Bedouin family.     

In vivo gene knockdown in rat dorsal root ganglia mediated by self-complementary adeno-associated virus serotype 5 following intrathecal delivery

We report here in adult rat viral vector mediate-gene knockdown in the primary sensory neurons and the associated cellular and behavior consequences. Self-complementary adeno-associated virus serotype 5 (AAV5) was constructed to express green fluorescent protein (GFP) and a small interfering RNA (siRNA) targeting mammalian target of rapamycin (mTOR). The AAV vectors were injected via an intrathecal catheter. We observed profound GFP expression in lumbar DRG neurons beginning at 2-week post-injection. Of those neurons, over 85% were large to medium-diameter and co-labeled with NF200, a marker for myelinated fibers. Western blotting of mTOR revealed an 80% reduction in the lumbar DRGs (L4-L6) of rats treated with the active siRNA vectors compared to the control siRNA vector. Gene knockdown became apparent as early as 7-day post-injection and lasted for at least 5 weeks. Importantly, mTOR knockdown occurred in large (NF200) and small-diameter neurons (nociceptors). The viral administration induced an increase of Iba1 immunoreactivity in the DRGs, which was likely attributed to the expression of GFP but not siRNA. Rats with mTOR knockdown in DRG neurons showed normal general behavior and unaltered responses to noxious stimuli. In conclusion, intrathecal AAV5 is a highly efficient vehicle to deliver siRNA and generate gene knockdown in DRG neurons. This will be valuable for both basic research and clinic intervention of diseases involving primary sensory neurons.     

First Philippine record of the parasitoid,Comperiella sp. (Hymenoptera: Encyrtidae): a potential biocontrol agent against Aspidiotus rigidus (Hemiptera: Diaspididae)

The encyrtid genus Comperiella Howard has so far not been reported in the Philippines, where there is currently an outbreak of the coconut scale insect Aspidiotus rigidus Reyne particularly in the southern parts of the island of Luzon and in some areas in Mindanao. Among Comperiella species, only C. unifasciata Ishii has been reported as a parasitoid of A. rigidus. We report not only new sightings of this parasitoid genus in the Philippines from surveys conducted in parts of the provinces of Laguna and Batangas, but also the discovery of a possibly new species that, like C. unifasciata, has been found to parasitize A. rigidus at a high rate. These findings have presented a potential of biological control against the coconut scale insect problem that has threatened the coconut industry in the country.     

DNA-Protein Complex in Circular DNA from Phage ϕ29

THE DNA of the B. subtilis phage ?29 has been described as unpermuted linear duplex molecules¹ of molecular weight 11 × 10⁶, but the formation of circular molecules has also been indicated, suggesting the existence of cohesive ends^1,2.     

Muscle transcriptomic analyses in Angus cattle with divergent tenderness

Beef tenderness contributes significantly to variation of beef palatability, and is largely influenced by various genetic and environmental factors. To identify candidate genes and pathways related to beef tenderness, we analyzed the longissimus dorsi (LD) muscle of Angus cattle that had different degrees of tenderness, measured by Warner-Bratzler shear force (WBSF). Microarray and RT-PCR analyses identified 53 genes that were differentially expressed in LD samples categorized as either tough or tender, including myosin, heavy chain 3 skeletal muscle embryonic (MYH3), myosin heavy chain 8 skeletal muscle perinatal (MYH8), guanylate binding protein 5 (GBP5), fatty acid binding protein 4 (FABP4), Stearoyl-coenzyme A desaturase (SCD), Fatty acid synthase (FASN), ubiquitin-like with PHD and ring finger domains 1 (UHRF1). Most of these genes are involved in lipid metabolism and skeletal muscle contraction. Employing Gene ontology (GO) and Ingenuity Pathway Analysis (IPA), several GO terms and pathways were found to be related to hydrolase, peptidase and GTPase activity, lipid metabolism, small molecule biochemistry, molecular transport, and tissue development. Overall, this analysis provides insight into the metabolic relationships between muscle biology and beef quality.     

重庆市蕨类植物区系调查和分析

重庆市有野生蕨类植物47科120属604种(含变种及以下分类单位)。其科属优势明显,其中蹄盖蕨科、金星蕨科、鳞毛蕨科和水龙骨科4个科包含了49属337种,占重庆市蕨类植物属、种总数的40.83%和55.79%;特有现象明显,地方特有种十分丰富,中国特有种和地方特有种类分别达到164种和33种;蕨类植物区系具有古老、孑遗和原始性等特点,表现出一定的热带性质或热带亲缘。