A simple porometer for precise recording of leaf resistance

A porometer, which can be easily constructed with a common photometricunit and yet records the air flow through a leaf blade accuratelyand sensitively, was developed and used to record the flow changesthrough Brassica chinensis leaves under several light, air andwater conditions. (Received May 17, 1973; )     

Ultraviolet reactivation of lambda phage: assay of infectivity of DNA molecules by spheroplast transfection

Prior irradiation of non-lysogenic bacteria by ultraviolet light leads to an increase in the viability of infecting irradiated λ phage (ultraviolet reactivation). Similarly, u.v. irradiation of wild type or uvrD bacteria lysogenic for λcIind^? increased the fraction of closed circular duplex phage DNA molecules formed after infection with u.v.-irradiated λ phage. The closed circular molecules isolated from the irradiated lysogens were shown to be free from u.v. damage by a spheroplast transfection assay. The increase of closed circular molecules is sufficient to explain the ultraviolet reactivation observed by the increase of viability of irradiated phage.In ultraviolet reactivation, damage must be erased on irradiated DNA molecules and the repair is independent of total replication of phage genomes, exchange of sister chromatids or recombination between phage genomes. Protein synthesis is necessary to increase the level of closed circular molecules of irradiated λ phage after irradiation of bacteria.     

The macula densa site of avian kidney

Summary The macula densa (MD) site of the kidney, at which the distal tubule is attached to the vascular pole of the glomerulus, was examined with the light microscope in domestic fowl and Japanese quail; and in the fowl also with the electron microscope. The characteristics of mammalian MD cells, as reported in the literature, are compared with those of the cells in the avian MD site. The avian cells possess some of the characteristics of mammalian MD cells and they are distinguishable from the cells in adjacent portions of the distal tubule. The Golgi system in the avian cells is apical to the nucleus, unlike in mammals where its location is basal. The cells in the avian MD sites can be considered as structurally transitional between the typical MD cells in mammals and the ordinary cells of the distal tubule. These findings are discussed in relation to the function of the avian kidney and to its control by the renin mechanism.* This investigation was supported in part by U.S. Public Health Service Research Grant HE 10338 from the National Heart Institute. We thank Mr. T. Takizawa for technical assistance. A preliminary report of this study was given at the 13th Annual Meeting of Japanese Society of Nephrology in Kyoto, 1970.     

Enzymatic Elimination of Collagen in the Alcian Blue Staining of Connective Tissue Ground Substance

Collagenase pretreatment of frozen-dried sections permits Alcian blue staining of mucopolysaccharides of connective tissue ground substance without the interference of collagen staining. Hyaluronidase elimination of Alcian blue staining confirms mucopolysaccharide as a substrate of the staining reaction.     

Chemical modification of the sugar part of methyl acarviosin: synthesis and inhibitory activities of nine analogues.

Nine analogues of methyl acarviosin (1), the core structure of acarbose and its homologues, the 6-hydroxy-(2), 6-azido-(3), 6-amino- (4), 6-acetamido-(5), 6-methoxy-(6), 6-hydroxy-2-O-methyl-(8), and 6-hydroxy-3-O-methyl derivatives (9), including the 5-methoxycarbonyl analogue (7) and 3,6-anhydro derivative (10) of 2, were synthesized by chemical modification of the sugar part of 2 derived by condensation of methyl 3,4-anhydro-alpha-D-galactopyranoside (17) and 4,7:5,6-di-O-isopropylidenevalienamine (26) or by direct coupling between 26 and the 6-substituted methyl 3,4-anhydro-alpha-D-galactopyranoside derivatives. Compounds 2 and 8 show notable inhibitory activity against yeast alpha-D-glucosidase almost comparable to that of 1. Introduction of a polar substituent at C-6 of 1 decreases the inhibitory activity. Interestingly, inversion of the conformation of the sugar part of 1 by introduction of the 3,6-anhydro bridge elicits almost no effect on the inhibitory activity.     

Total synthesis of the modified ganglioside de-N-acetyl-GM3 and some analogs.

Methyl[methyl 4,7,8,9-tetra-O-acetyl-5-(tert-butoxycarbonylamino)-3,5- dideoxy-2-thio-D-glycero-alpha-D-galacto-2-nonulopyranosid]onat e was used for the glycosylation of benzyl O-(2,6-di-O-benzyl-beta-D-galactopyranosyl)- and benzyl O-(2,3-di-O-benzyl-beta-D-galactopyranosyl)-(1----4)-3,6-di-O-benzyl- 2-O-pivaloyl-beta-D-glucopyranoside to give benzyl O-[methyl 4,7,8,9-tetra-O-acetyl-5-(tert-butoxycarbonylamino)- 3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosylonate]-(2-- --3)-O-(2,6-di-O-benzyl-beta-D-galactopyranosyl)-(21) and benzyl O-[methyl 4,7,8,9-tetra-O-acetyl-5-(tert-butoxycarbonylamino)-3,5- dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosylonate]-(2----6) -O-(2,3-di- O-benzyl-beta-D-galactopyranosyl)-(1----4)-3,6-di-O-benzyl-2-O-pivaloyl- beta-D-glucopyranoside (18), respectively, accompanied by the beta-linked isomers 22 and 19, respectively. Compounds 18, 21, and 22 were converted into the corresponding glycotriosyl donors which, upon coupling with (2S,3R,4E)-3-O-benzoyl-2-N-tetracosanoylsphingenine, afforded completely protected ganglioside analogs 39, 40, and 41, respectively. Deprotection of 40, 41, and 39 completed the synthesis of the modified ganglioside de-N-acetyl-GM3, a stereoisomer, and a regioisomer. The N-deprotected forms of 40 and 39, on successive treatment with methyl isocyanate and O-deprotection, gave the N-(N-methylcarbamoyl) analogs of GM3 and its regioisomer.     

Cloning and Inactivation of a Gene Essential to Inorganic Carbon Transport of Synechocystis PCC6803

A clone (HP-1) which transforms the high CO₂-requiring mutant (RKb) of Synechocystis PCC6803 defective in inorganic carbon transport to the wild-type (WT) phenotype was isolated from a WT genomic library. The clone contained a 5.4 kilobase-pair DNA insert. Complementation tests with subclones derived from HP-1 allowed the mutation in RKb to be located within 141 base-pair nucleotides. Sequencing of nucleotides in this region revealed an open reading frame encoding a hydrophobic protein consists of 80 amino acids. A defined mutant (M9) constructed by inactivating this putative inorganic carbon transport gene, designated ictA, was unable to transport CO₂ and HCO₃⁻ into the intracellular inorganic carbon pool. Cloning and sequence analysis of the respective RKb gene revealed a base substitution which generates a stop codon in the middle of ictA.