NADPH: protochlorophyllide oxidoreductases in white pine (Pinus strobus) and loblolly pine (P. taeda). Evidence for light and developmental regulation of expression and conservation in gene organization and protein structure between angiosperms and gymnosperms

NADPH: protochlorophyllide oxidoreductase (pchlide reductase, EC 1.6.99.1) catalyzes the light-dependent reduction of protochlorophyllide in higher plants. Cloned cDNAs encoding two distinct pchlide reductases were isolated from a lambda gt11 library constructed from poly(A)+ RNA prepared from the cotyledons of dark-grown white pine (Pinus strobus) seedlings and a nuclear gene (lpcr) analogous to one of these cDNAs has been characterized from loblolly pine (P. taeda). The pine gene encodes an approximately 43 kDa precursor polypeptide consisting of a 334-amino acid mature protein and a 66-amino acid transit peptide. The deduced primary structures for the pine proteins are highly homologous to those reported from monocots and dicots. The coding portion of the pine lpcr gene is interrupted by four introns. The placement of these introns within the pine lpcr gene is identical to that observed in pea (Pisum sativum), suggesting conservation in gene organization between dicot and gymnosperm species. Western blot analysis using polyclonal antiserum against oat pchlide reductase detected in extracts of dark-grown pine cotyledons a single immunoreactive protein, which declined in abundance during a 48 h period of illumination with white light. Cotyledons of dark-grown seedlings were also found to accumulate high levels of pchlide reductase mRNA; however, little or no change in the steady-state levels of mRNA encoding pchlide reductase was observed in these tissues following illumination. Stem tissue of dark-grown seedlings did not contain significant levels of pchlide reductase mRNA, whereas stems of light-grown plants of the same age accumulated substantial amounts of the message. These results suggest that light and the developmental age of the tissue affect regulation of lpcr expression in pine.

Peritoneal membrane plasmapheresis

A novel process has been devised that uses the peritoneal membrane to remove plasma proteins from the body at a rate comparable to conventional extracorporeal plasma-pheresis. A vasodilator (4 mg histamine phosphate) is added to 1 liter of hypertonic solution (485 mOsmol/L), and infused intraperitoneally with a residence time of 4 hr. Plasma containing proteins is convected across the peritoneum through open pores into the cavity and removed. The next alternating infusion is with a hypotonic solution (214 mOsml/L) containing a vasoconstrictor (1.0 mg norepinephrine). This infusion restores the fluid removed from the subject in the previous exchange, and prevents the rapid fall-off in protein removal rates obtained with repeated infusions with vasodilators only. Peritoneal membrane plasmapheresis was successfully tested on canines, with protein removal rates of between 30% and 50% of total serum protein per day for 13 days over a 22 day period. Peritoneal membrane plasmapheresis represents a potentially inexpensive, continuous/nightly home treatment for protein mediated diseases treatable by extracorporeal plasmapheresis.

Molecular cloning, nuclear gene structure, and developmental expression of NADPH: protochlorophyllide oxidoreductase in pea (Pisum sativum L.)

Complementary DNA clones and a corresponding nuclear gene (lpcr) encoding the NADPH-dependent protochlorophyllide oxidoreductase (pchlide reductase, EC 1.6.99.1) have been characterized from pea (Pisum sativum L.). The pea lpcr gene encodes a 43,118 Da precursor polypeptide comprised of a transit peptide of 64 amino acids and a mature protein of 336 amino acids. The coding portion of the gene is interrupted by four introns, two of which are located within the transit peptide coding portion of the gene. The deduced primary structure for the pea protein is similar to those reported for Arabidopsis and two monocot species. Northern blot analysis revealed little to no decrease in steady-state levels of mRNA encoding the enzyme in etiolated leaves illuminated with continuous white light for up to 48 h. In contrast, western blot analysis showed that the major immunoreactive species present in whole leaf extracts decreased to nearly undetectable levels during this same 48 h period. These results suggest that pchlide reductase activity in pea is primarily regulated post-transcriptionally, most likely at the level of translation initiation/elongation or protein turnover.

cDNAs encoding members of a family of proteins related to human sterol carrier protein 2 and assignment of the gene to human chromosome 1 p21----pter

Sterol carrier protein 2 (SCP2) is believed to play a key role in intracellular lipid movement. Here we report the cloning and nucleotide sequences of cDNAs encoding SCP2-related proteins of 58.85 kD and 30.8 kD and the assignment of the SCP2 gene to human chromosome 1 p21-pter. The SCP2-related proteins share common deduced carboxyl amino acid sequences with SCP2 and the cDNAs have a common 3' untranslated nucleotide sequence. The mRNAs encoding these proteins increased in a coordinate fashion as human placental cytotrophoblasts differentiated into syncytiotrophoblasts in culture. Our observations document the existence of a family of related proteins encoded by the human SCP2 gene.

[The clinical use of sodium hyaluronate eyedrops as a substitute for tears]

The present paper reports on the curative effect of the 0.1% Sodium hyaluronate (Na-HA) eyedrops jointly manufactured by Guangzhou Red Cross Hospital and Guangzhou Institute of Medical & Pharmaceutical Industry. 70 cases were studied. There were kerato-conjunctivitis sicca, lagophthalmos corneal fluorescein diffuse punctate epithelial lesion caused by contact lens, and keratitis punctata superficialis. The results showed effective treatment which occupied 95.7%. In the discussion, the authors point out that Na-HA has the same stagnatisity and elasticity as biotears because of its adhesion to the corneal epithelium. Moreover, it has the water-retaining microsponge action similar to that of mucopolysaccharide. Hence, Na-HA has protective effects on corneal epithelium. Finally, the authors conclude that Na-HA eyedrop is so far the most ideal substitute for tears and superior to other artificial tears.