Characterization of lacrimal gland carbonic anhydrase VI.

We have previously demonstrated by immunohistochemistry the presence of secreted carbonic anhydrase (CA VI) in the acinar cells of the rat lacrimal glands. In this study we purified the sheep lacrimal gland CA VI to homogeneity and demonstrated by Western analysis that it has the same apparent subunit molecular weight (45 kD) as the enzyme isolated from saliva. RT-PCR analysis showed that CA VI mRNA from the lacrimal gland was identical to that of the parotid gland CA VI mRNA. An RIA specific for sheep CA VI showed the lacrimal gland tissue concentration of the enzyme to be 4.20 +/- 2.60 ng/mg protein, or about 1/7000 of the level found in the parotid gland. Immunohistochemistry (IHC) and in situ hybridization (ISH) showed that lacrimal acinar cells expressed both immunoreactivity and mRNA for CA VI. Moreover, CA VI immunoreactivity was occasionally observed in the lumen of the ducts. Unlike the parotid gland, in which all acinar cells expressed CA VI immunoreactivity and mRNA, only some of the acinar cells of the lacrimal gland showed expression. These results indicate that the lacrimal gland synthesizes and secretes a very small amount of salivary CA VI. In tear fluid, CA VI is presumed to have a role in the maintenance of acid/base balance on the surface of the eye, akin to its role in the oral cavity.     

Localization of laminin alpha4-chain in developing and adult human tissues.

Recent studies suggest important functions for laminin-8 (Ln-8; alpha4beta1gamma1) in vascular and blood cell biology, but its distribution in human tissues has remained elusive. We have raised a monoclonal antibody (MAb) FC10, and by enzyme-linked immunoassay (EIA) and Western blotting techniques we show that it recognizes the human Ln alpha4-chain. Immunoreactivity for the Ln alpha4-chain was localized in tissues of mesodermal origin, such as basement membranes (BMs) of endothelia, adipocytes, and skeletal, smooth, and cardiac muscle cells. In addition, the Ln alpha4-chain was found in regions of some epithelial BMs, including epidermis, salivary glands, pancreas, esophageal and gastric glands, intestinal crypts, and some renal medullary tubules. Developmental differences in the distribution of Ln alpha4-chain were detected in skeletal muscle, walls of vessels, and intestinal crypts. Ln alpha4- and Ln alpha2-chains co-localized in BMs of fetal skeletal muscle cells and in some epithelial BMs, e.g., in gastric glands and acini of pancreas. Cultured human pulmonary artery endothelial (HPAE) cells produced Ln alpha4-chain as M(r) 180,000 and 200,000 doublet and rapidly deposited it to the growth substratum. In cell-free extracellular matrices of human kidney and lung, Ln alpha4-chain was found as M(r) 180,000 protein.     

Production of gibberellin-like substance in the embryo of barley during germination

Summary Embryos were excised from barley seeds, their homogenates were incubated with ficin, and their content in gibberellin-like substance was assayed by means of -amylase-producing activity, but no gibberellin-like substance could be detected.Embryos free from endosperm which were cultured for five days produced measurable amounts of gibberellin-like substance. This substance was not produced when a carbon source was absent from the medium, or when air was removed after 2 days of aerobic culture. CCC and Phosfon D (at the concentration of 2×10^-4 M and 0.8×10^-4 M, respectively) inhibited the formation of the gibberellin-like substance in cultured embryos without affecting their growth.Mevalonic acid could be used as a carbon source in the culture of the embryos. The formation of the gibberellin-like substance was in this case inhibited by 0.8×10^-4 M Phosfon D, but was not inhibited by 2×10^-3 M CCC.     

Genetic evidence of peripheral isolation and low diversity in marginal populations of the Acropora hyacinthus complex

Coral Reefs - Zooxanthellate corals are found throughout the tropics, but also extend into subtropical and marginal locations due to the presence of warm ocean currents. The population history of...     

Spawning and fertility of F<Subscript>1</Subscript> hybrids of the coral genus <Emphasis Type="Italic">Acropora</Emphasis> in the Indo-Pacific

The role of hybridization through multi-specific synchronous spawning in the evolution of reef-building corals has been discussed since the 1990s, particularly for the genus Acropora. However, F₁ hybrids have been reported as common in only one case in the Caribbean, with no evidence of mechanisms that would allow continuous reproduction of the hybrids. In this study, we report for the first time the fecundity of two F₁ hybrid colonies produced experimentally from two Indo-Pacific species, A. intermedia and A. florida. These F₁ hybrids spawned at the same time as the parental corals. Backcrossing and F₁ hybrid crossing were successful in both directions. Furthermore, more than 90% self-fertilization was achieved in an F₁ hybrid, although it was negligible in the parental corals. While it is possible that the F₁ hybrid was a chimera, these results suggest that some products of interspecific hybridization may persist as the offspring of self-fertilizing F₁ hybrids.     

Cu,Zn-SOD deficiency induces the accumulation of hepatic collagen

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic diseases, and results in the development of fibrosis. Oxidative stress is thought to be one of the underlying causes of NAFLD. Copper/zinc superoxide dismutase (SOD1) is a primary antioxidative enzyme that scavenges superoxide anion radicals. Although SOD1 knockout (KO) mice have been reported to develop fatty livers, it is not known whether this lack of SOD1 leads to the development of fibrosis. Since the accumulation of collagen typically precedes liver fibrosis, we assessed the balance between the synthesis and degradation of collagen in liver tissue from SOD1 KO mice. We found a higher accumulation of collagen in the livers of SOD1 KO mice compared to wild type mice. The level of expression of HSP47, a chaperone of collagen, and a tissue inhibitor (TIMP1) of matrix metalloproteinases (a collagen degradating enzyme) was also increased in SOD1 KO mice livers. These results indicate that collagen synthesis is increased but that its degradation is inhibited in SOD1 KO mice livers. Moreover, SOD1 KO mice liver sections were extensively modified by advanced glycation end products (AGEs), which suggest that collagen in SOD1 KO mice liver might be also modified with AGEs and then would be more resistant to the action of collagen degrading enzymes. These findings clearly show that oxidative stress plays an important role in the progression of liver fibrosis.     

Inhibitors of amyloid β-protein aggregation mediated by GM1-containing raft-like membranes

The aggregation (fibril formation) of amyloid β-protein (Aβ) is considered to be a crucial step in the etiology of Alzheimer's disease (AD). The inhibition of Aβ aggregation and/or decomposition of fibrils formed in aqueous solution by small compounds have been studied extensively for the prevention and treatment of AD. However, recent studies suggest that Aβ aggregation also occurs in lipid rafts mediated by a cluster of monosialoganglioside GM1. This study examined the effects of representative compounds on Aβ aggregation and fibril destabilization in the presence of GM1-containing raft-like liposomes. Among the compounds tested, nordihydroguaiaretic acid (NDGA), rifampicin (RIF), tannic acid (TA), and quercetin (QUE) showed strong fibrillization inhibitory activity. NDGA and RIF inhibited the binding of Aβ to GM1 liposomes by competitively binding to the membranes and/or direct interaction with Aβ in solution, thus at least partly preventing fibrils from forming. Coincubation of Aβ with NDGA, RIF, and QUE in the presence of GM1 liposomes resulted in elongate particles, whereas the presence of TA yielded protofibrillar structures. TA and RIF also destabilized fibrils. The most potent NDGA prevented Aβ-induced toxicity in PC12 cells by inhibiting Aβ accumulation. Furthermore, a comparison of the inhibitory effects of various compounds between aqueous-phase and GM1-mediated aggregation of Aβ suggested that the two aggregation processes are not identical.