Anti-diabetic and anti-oxidative activity of fixed oil extracted from Ocimum sanctum L. leaves in diabetic rats

Ocimum sanctum L. (OS) leaves have been shown to exert diverse potential benefits in a variety of stress conditions. The present study was conducted to elucidate the effects of the fixed oil extracted from OS leaves on the blood glucose levels and serum lipid profile of streptozotocin-induced diabetic rats. In addition, the anti-oxidative activity of OS leaves to protect various organs including the liver, kidney and heart was investigated. The fixed oil of the OS leaves was extracted using hexane, and the various fatty acid contents of the oil were determined using gas chromatography-mass spectrometry. Male Wistar rats were allocated into three groups (n=7 per group): Normal control rats, diabetic rats and diabetic rats fed daily with the fixed oil for three weeks. The results showed that α-linolenic acid was the primary fatty acid contained in the fixed oil of OS. After 3 weeks of diabetic induction, the rats exhibited increased blood glucose levels and serum lipid profile, in addition to elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine kinase MB subunit (CK-MB), creatinine and blood urea nitrogen (BUN). The fixed oil significantly decreased the elevated levels of blood glucose, the serum lipid profile and the levels of serum creatinine and BUN (P<0.001), without exerting significant effects on the elevated serum levels of AST, ALT, LDH and CK-MB. Furthermore, the fixed oil increased the diabetically-reduced levels of serum insulin and decreased the rat kidney weight. Fixed oil suppressed the elevated thiobarbituric acid reactive substances (TBARS) level and increased the activity of various antioxidative enzymes in the rat renal tissue. By contrast, the fixed oil had no effect on the elevated TBARS level and the inhibited activity of the antioxidative enzymes in the rat liver and cardiac tissues. Histopathological results indicated that the fixed oil preserved the renal tissue against oxidative stress in diabetes. In summary, the results of the present study suggest that the fixed oil extracted from OS leaves exerted anti-hyperglycemic, anti-hyperlipidemic and free radical scavenging effects in diabetic rats, thus providing renal protection against diabetes. The α-linolenic acid contained in the fixed oil may be responsible for these effects.

Knocking down a Taura syndrome virus (TSV) binding protein Lamr is lethal for the whiteleg shrimp Penaeus vannamei

A cDNA encoding a laminin receptor protein (Lamr) has been isolated from hemocytes of the Pacific white shrimp Penaeus (Litopenaeus) vannamei (Pv), based on primers designed from a previously published Lamr sequence of a Taura syndrome virus (TSV) binding protein of the black tiger shrimp Penaeus monodon (Pm). The deduced amino acid sequence of PvLamr shares 97% identity with PmLamr and has significant homology to laminin receptors and ribosomal protein p40 from various organisms. Tissue distribution analysis by RT-PCR revealed that Lamr transcripts were widely expressed in all tested tissues of P. monodon and Penaeus vannamei. PmLamr was constructed and expressed in Escherichia coli, and the recombinant protein was purified and used to raise a polyclonal antibody. The antiserum reacted with purified recombinant PmLamr and crude muscle tissue proteins from both P. monodon and P. vannamei, but not with hemocyte-free shrimp hemolymph. Examination of protein localization by immunohistochemical analysis revealed the presence of Lamr positive cytoplasm in subcuticular epithelial cells, hematopoietic tissues, epithelial cells of the stomach, epithelial cells of the anterior midgut cecum, antennal gland epithelial cells, F cells of the hepatopancreas, cells in the ovarian zone of proliferation and spheroid cells in the lymphoid organ. RNA interference-mediated silencing of the messenger from Lamr in P. vannamei led to shrimp mortality and indicated an essential function of Lamr for shrimp viability. A negative consequence was that the effect of Lamr knockdown on shrimp infection by Taura syndrome virus could not be assessed.

Low viral loads and lymphoid organ spheroids are associated with yellow head virus (YHV) tolerance in whiteleg shrimp Penaeus vannamei

Yellow head virus (YHV) is an invertebrate nidovirus that has caused mass mortality in penaeid shrimp since 1990. Several YHV types are known, but only the original type (YHV-type 1 or YHV-1) is highly virulent. Most studies have focused on acute YHV-1 infections and there is limited work on YHV-1 survivors. We compared moribund and surviving (14%) whiteleg shrimp Penaeus (Litopenaeus) vannamei from an experimental challenge with YHV-1. Although grossly normal, all survivors were positive for YHV-1 by specific, reverse transcriptase polymerase chain reaction (RT-PCR) assays, histological analysis or transmission electron microscopy (TEM), indicating that they were not resistant but tolerant to YHV-1. On the other hand, real-time PCR analysis revealed that mean YHV-1 copies/ng total RNA for survivors (2.8x10(4) +/- 6.9x10(4)) were approximately 40 times lower (P<0.05) than those in moribund shrimp (1.2x10(6) +/- 6.7x10(5)copies/ng total RNA). This was confirmed by strong positive immunohistochemical and in situ hybridization (ISH) reactions for YHV-1 in lymphoid organ tubules (LOT) of moribund shrimp and weak positive reaction only in lymphoid organ spheroids (LOS) of survivors. TEM revealed morphologically complete YHV virions in both groups. Furthermore, immuno-TEM and Western blot analysis revealed that YHV-1 structural proteins gp116 and p20 were present at comparable reactive levels in each group. Thus, YHV-1 tolerance was not associated with absence of gp116 as previously reported for palaemonid shrimp. Instead, it was associated with the presence of YHV-positive LOS and a relatively low viral load.