A functionally unique anti-CD3 monoclonal antibody cross-reactive with basal keratinocytes

Monoclonal antibodies (mAb) 147, 446, and 454 each recognize different epitopes of CD3. The CD3 epitope recognized by mAb 446 is functionally unique for the T cell. In contrast to mAb 147 and 454, mAb 446 induces modulation of surface CD3 with delayed kinetics and, hence, is impaired in inducing a refractory state in the T cell to subsequent anti-CD3-induced helper function. MAb 446 (but not other anti-CD3 mAb, including mAb 147, 454, OKT3, and anti-Leu4) recognizes a cytoplasmic determinant within basal keratinocytes. Extraction of keratinocytes with nonionic detergent and 2 M NaCl abolished subsequent staining with mAb 446 but enhanced subsequent staining with anti-keratin mAb, suggesting that this cross-reactive determinant is not keratin. Immunoprecipitation of internally labeled keratinocytes with the anti-CD3 mAb 147 and 446 failed to reveal specific bands, whereas these same mAb immunoprecipitated specific bands from internally labeled CD3+ Jurkat cells corresponding to previously identified CD3 subunits, suggesting that the cross-reactive determinant in keratinocytes is also not CD3. The cross-reactivity is not species specific, in that mAb 446 stained a mouse keratinocyte line, nor is it absolutely keratinocyte specific, in that mAb 446 stained one of the two nonkeratinocyte human epithelial cell lines tested. This study raises the possibility that perturbation of unique CD3 epitopes may have unique effects on T cell surface events and subsequent activation and function.     

Indole alkaloids as systematic markers of the Apocynaceae

Indole alkaloids can be characterized by skeletal specialization (S), determined upon consideration of their relative position on a biogenetic map and the number of their naturally occurring substitutional derivatives, as well as by oxidation level (O). The mean (S) and (O) for contained alkaloids of a given plant taxon are taken to represent evolutionary advancement parameters, respectively EA_s and EA_o.A correlation of these EA_s/EA_o values for tribes of the Apocynaceae-Plumerioideae reveals a chemical gradient, given by gradually increasing EA_s and EA_o values, to link Carisseae-Alstonieae-Rauvolfieae-Tabernaemontaneae.     

A sequence element necessary for self-cleavage of the antigenomic hepatitis delta RNA in 20 M formamide.

The genomic and antigenomic RNAs of hepatitis delta virus are capable of self-cleavage and show no significant sequence similarities to other known self-cleaving RNAs. We have derived an antigenomic delta RNA which cleaves to completion in 15 s in 9 mM magnesium at 37 degrees C and is capable of efficient self-cleavage in concentrations of formamide as high as 20 M. Cleavage in high concentrations of denaturant is dependent upon the presence of a polypurine sequence element, GGAGA, located between 81 and 85 nucleotides downstream of the cleavage site. Mutation of the initial G81G82 to C81C82, or removal of the sequence element, results in a loss of the ability to cleave in high formamide concentrations. Changing the final U-2C-1 of a pyrimidine-rich region, UCUUC, just upstream of the cleavage site, to G-2G-1 severely affects the self-cleavage, but introducing the two mutations, GG to CC and UC to GG, into the same molecule, restoring potential base pairing, partially restores the formamide stability. Relocating the GGAGA sequence upstream of the cleavage site also results in partial restoration of the formamide cleavage. Although the GGAGA sequence is important for self-cleavage under denaturing conditions, it does not appear to be necessary for HDV RNA cleavage in normal buffer conditions.     

Control of the antibody response of C57BL/6 Lyt-congenic strains to the Lyt-3.1 alloantigen by a gene linked to theLyt-2 locus

Congenic anti-Lyt-3.1 sera have recently been produced by immunizing B6-Lyt-2^a mice with thymocytes from either B6-Lyt-2^a, Lyt-3^a or B6-Lyt-2^a, Lyt-3^a, H-2^k mice (Boos et al. 1978). Surprisingly, mice of the congenic strain B6 failed to produce either anti-Lyt-2.1 or anti-Lyt-3.1 cytotoxic antibodies after identical immunizations. To determine the genetic basis for the difference in response to Lyt-3.1, (B6 × B6-Lyt-2^a)F_a mice and progeny of the backcross, (B6 × B6-Lyt-2^a)F₁ × B6-Lyt-2^a, were immunized with B6-Lyt-2^a, Lyt-3^a, H-2^k thymocytes. In addition, thymic biopsies of backcross progeny were performed and thymocytes tested for the Lyt-2.2 antigenic specificity. Results indicate that gene(s) governing the immune response to Lyt-3.1 is (are) linked to theLyt-2 locus, and that the responder allele (linked toLyt-2 ^a ) shows very poor penetrance in Lyt-2^a/Lyt-2^b mice.     

Plant phosphoglucose isomerase genes lack introns and are expressed in Escherichia coli

Nuclear genes that appear to encode both cytosolic and plastid isozymes of phosphoglucose isomerase (PGI), an essential glycolytic enzyme, have been isolated from three diploid species of the annual wild flower genus Clarkia (Onagraceae). The genes do not contain introns and are expressed to varying degrees in Escherichia coli when cloned in either Charon 35 phage or pUC plasmid vectors. The PGI proteins synthesized in E. coli form dimers, are catalytically active, and their electrophoretic mobilities are similar to those of appropriate Clarkia PGIs. The nucleotide sequence of a gene encoding a plastid isozyme of C. unguiculata is described.     

Methyl- and methylthio-phenanthrenes from Micrandropsis scleroxylon

The trunk wood of Micrandropsis scleroxylon W. Rodr. (Euphorbiaceae) contains besides sitosterol, stigmasterol and ferulic acid, three novel compou     

Development of species identification in ducklings: XI. Embryonic critical period for species-typical perception in the hatchling

In the embryonic stages prior to hatching, the contact-contentment call of the Peking duck (domesticated Anas platyrhynchos) is more highly variable (2–6 notes/s) than it is after hatching (4–6 notes/s). The embryos must be exposed to the normally wide range of repetition rates of their contact-contentment call (2, 4, 6 notes/s) if their preference for the species maternal call is to be normal at 24 h after hatching. Exposure of muted embryos to the higher (4, 6 notes/s) or lower (2, 4 notes/s) portions of the normal range was ineffective. Thus the normally highly variable nature of the embryo's vocalizations fits the requirements of its developing auditory system. An embryonic critical period was also demonstrated: when muted hatchlings were exposed to the rates typical of the postnatal period (4, 6 notes/s), or even the more widely variable rates of the embryonic period (2, 4, 6 notes/s), they failed to show a preference for the normal maternal call at 24 or 48 h after hatching. Thus the precise developmental linkage involves maturational stage as well as the representativeness of the stimulation.