Lipoxygenase from banana leaf: purification and characterization of an enzyme that catalyzes linoleic acid oxygenation at the 9-position

The objective of the present study was to purify and characterize the lipoxygenase (LOX) from banana leaf (Giant Cavendishii, AAA), an unutilized bioresource. LOX was extracted, isolated, and purified 327-fold using 25-50% saturation of ammonium sulfate fractionation, hydroxyapatite column separation, and gel filtration on Superdex 200. The molecular mass of the purified LOX was 85 kDa, K(m) was 0.15 mM, and V(max) was 2.4 microM/min.mg using linoleic acid as substrate. Triton X-100 was required in the extraction medium; otherwise, no LOX activity was detected. LOX activity increased with the concentration of Triton X-100 with an optimum at 0.1%. The optimal pH of the purified LOX from banana leaf was 6.2, and optimal temperature was 40 degrees C. The LOX showed the highest reactivity toward 18:2 followed by 18:3 and 20:4. A very low reaction rate was observed toward 20:5 and 22:6. On the basis of retention time in normal phase HPLC, the products of 18:2 or 18:3 catalyzed by purified LOX were hydroperoxyoctadecadienoic acid or hydroperoxyoctadecatrienoic acid. It seems that 9-LOX is the predominant enzyme in banana leaf. Banada leaf dried at 110 degrees C for 2 h developed algal aroma. Banana leaf extract stored at 10 degrees C for 12 h formed an oolong tea-like flavor. Banana leaf extract reacted with 18:2 or soybean oil pretreated with bacterial lipase produced green and melon-like aroma, whereas the same reaction with 18:3 produced a sweet, fruity, cucumber-like flavor note.     

Glutamate-activated chloride channels: Unique fipronil targets present in insects but not in mammals

Selectivity to insects over mammals is one of the important characteristics for a chemical to become a useful insecticide. Fipronil was found to block cockroach GABA receptors more potently than rat GABA_A receptors. Furthermore, glutamate-activated chloride channels (GluCls), which are present in cockroaches but not in mammals, were very sensitive to the blocking action of fipronil. The IC₅₀s of fipronil block were 30 nM in cockroach GABA receptors and 1600 nM in rat GABA_A receptors. Moreover, GluCls of cockroach neurons had low IC₅₀s for fipronil. Two types of glutamate-induced chloride current were observed: desensitizing and non-desensitizing, with fipronil IC₅₀s of 800 and 10 nM, respectively. We have developed methods to separately record these two types of GluCls. The non-desensitizing and desensitizing currents were selectively inhibited by trypsin and polyvinylpyrrolidone, respectively. In conclusion, in addition to GABA receptors, GluCls play a crucial role in selectivity of fipronil to insects over mammals. GluCls form the basis for development of selective and safe insecticides.     

Alpinia zerumbet potentially elevates high-density lipoprotein cholesterol level in hamsters

In folkloric plant medicines, Alpinia zerumbet (AZ) has been popularly recognized as an exellent hepatoprotector. To search for a good high-density lipoprotein cholesterol (HDL-C) elevating herbal preparation, we examined AZ for its antioxidant and hypolipidaemic bioactivities, especially its HDL-C elevating activity. AZ seeds contain 0.51% essential oils (SO), which are comprised of monoterpenoids, oxygenated monoterpenoids, sesquiterpenoids, oxygenated sesquiterpenoids, aldehydes, acid, and esters. Gas chromatography/mass spectrometry analysis indicated that most of the monoterpenes and sesquiterpenes were recoverable in pentane eluent, whilst the oxygenated monoterpenoids and sesquiterpenoids remained in ether eluent. The high contents of rutin, quercetin, and polyphenolics in ethanolic extract of AZ seeds exhibit moderate antilipoperoxidative but potent DPPH free radical scavenging bioactivities. Conclusively, both seed powder (SP) and SO are effective hypolipidaemics with amazingly potent HDL-C elevating capabilities. On the basis of hepatoprotectivity, SP is a more feasible hypolipidemic agent as well as a promising HDL-C elevating plant medicine.     

Multilocus phylogeography and ecological niche modeling suggest speciation with gene flow between the two Bamboo Partridges

Background: Understanding how species diversify is a long-standing question in biology. The allopatric speciation model is a classic hypothesis to explain the s...     

The ability of <Emphasis Type="Italic">Papaya ringspot virus</Emphasis>strains overcoming the transgenic resistance of papaya conferred by the coat protein gene is not correlated with higher degrees of sequence divergence from the transgene

The coat protein (CP) gene mediated transgenic resistance is found to be the best approach for protecting papaya plants against the destructive disease caused by Papaya ringspot viruses(PRSV). In order to study the variability of PRSV and the potential threat to the CP-transgenic resistance, five virus isolates were collected from transgenic plants of papaya line 16-0-1, which carry the CP gene of the typical mosaic strain of Taiwan PRSV YK, in an approved test field and fourteen from untransformed papaya plants in different areas of Taiwan. The results of biological, serological, and molecular characterization indicated that all isolates are related to PRSV YK. Among them, the isolate 5--19 from the transgenic line and the isolates CS and TD2 from untransformed papaya were able to overcome the YK CP gene-mediated resistance of papaya lines 18--2--4, 17-0-5, and 16-0-1, which provide high degrees of resistance to different geographic PRSV strains of Hawaii (HA), Mexico (MX), and Thailand (TH). These three isolates were also able to cause symptoms on untransformed papaya plants more severe than those induced by YK. In addition to the host reactions, the variability of the collected 19 isolates was also analyzed and compared with YK and other geographic strains by heteroduplex mobility assay (HMA) and sequence analyses. The results of HMA indicated that the CP genes of isolates 5--19 and TD2 are more divergent than those of other isolates when compared with YK. However, sequence analyses of the transgenic-resistance overcoming isolates 5-19, CS, and TD2 revealed that their CP coding regions and the 3 untranslated regions (UTRs) share nucleotide identities of 93.9–96.6% and 94.2–97.9% with those of YK, respectively; whereas the other geographic strains of HA, MX, and TH that could not overcome the transgenic resistance share lower nucleotide identities of 89.8–92.6% and 92.3–95.3% with those of YK, respectively. Our results indicate that the ability for overcoming the transgenic resistance is not solely correlated with higher degrees of sequence divergence from the transgene. The possible mechanism for overcoming the transgenic resistance and the potential threat of these PRSV strains to the application of the transgenic papaya lines carrying PRSV YK CP gene are discussed.     

Maxillary bone epithelial cyst in an adult miniature schnauzer

Maxillary bone epithelial cyst is rare in dogs. A 5-year-old, spayed female miniature schnauzer developed a swelling below the nasal canthus of left eye. Plain radiograph demonstrated a 1.5 cm diameter of radiolucent lesion on the maxillary bone anteroventral to the eye, and contrast dacryocystorhinography confirmed an obstructed nasolarcrimal duct. The swelling showed poor response to antibiotic treatment but responded well to oral prednisolone. Exploratory surgery revealed a cyst-like structure filled with brown serous fluid. Histopathological examination of the removed cyst revealed a double cuboidal epithelial cyst. The dog recovered rapidly after surgery, and the swelling had not recurred for a 36-month follow-up. It is the first case of periorbital bone epithelial cyst reported in an adult miniature schnauzer.     

Infiltrating Foxp3+ Regulatory T cells and Histopathological Features in Canine Classical and Spermatocytic Seminomas

In humans, regulatory T (T reg) cells are known to play a critical role in both the regulation of immune homoeostasis and the progression of cancer. However, there is little information about the identification, characterization and the function of T reg cells in canine tumours. We identified T reg cells in 28 canine seminoma samples using a Forkhead box P3 (Foxp3) antibody and investigated the relationship between T reg cell infiltration and histopathological features of classical and spermatocytic seminomas (SE and SS, respectively). The Foxp3 protein showed nuclear immunostaining in infiltrating lymphocytes, and Foxp3+ cells were diffused or focally distributed in seminoma tissues. Foxp3+ cells were frequently present in the SS histotype, in seminomas that showed no evidence of tumour cell invasion into the vessels and in seminomas showing a diffuse growth pattern with three cell types. Neither the SE/SS histotype nor the histopathological features of the tumour correlated with Foxp3+ cell counts. These results indicate that Foxp3+ T reg cells may be associated with a less malignant histological phenotype or may not play a critical role in the immune response of canine seminomas. Moreover, Foxp3+ T reg cells may be associated with SS seminoma, but further studies, involving a larger number of samples, are required to better understand whether these cells play a critical role in the immune response in canine seminomas. This is the first report to demonstrate the characteristics of T reg cell infiltration in canine seminoma.