A technique for electrophoresis in multiple-concentration agarose gels

A technique has been developed for embedding several agarose gels (running gels), each of a different agarose concentration, within a single 1.5% agarose slab. Equal portions of a sample were placed at the origin of each running gel and were simultaneously subjected to electrophoresis. Protein within the running gels was detected by staining with Coomassie blue; 0.2% gels were the least concentrated gels that were stained without gel breakage. Using the above technique, the dependence of electrophoretic mobility on agarose concentration has been measured for bacteriophage T7 capsids and a capsid dimer.     

The phagocytosis stimulating peptide tuftsin: Further look into structure-function relationships

Summary Sixteen new analogs of the phagocytosis-stimulating peptide tuftsin have been synthesized. The biological activities of these synthetic peptides, in which either the C-terminal or both C- and N-terminals are chemically altered, were evaluated by studying their effects on the phagocytosis of heat-killed yeasts and on the reduction of the dye nitroblue tetrazolium by normal human polymorphonuclear leukocytes. The results demonstrate that the integrity of the guanidine side chain of arginine at position four of tuftsin is crucial for maximal activity. Modification, even in side chain length, of the guanidine leads to decreasing activity. Preservation of the positive charge of position four of tuftsin yields analogs possessing considerable activity. Simultaneous alterations of both C- and N-terminal results in diminishing activites. The results of this study are discussed in relation to the structural features of tuftsin. It appears that interaction between the carboxyl of Arg⁴ and the amino group of Thr¹ which would indicate a specific conformation such as a 4 1 -turn are not favored.     

Sexual dimorphism and resource allocation in male and female shrubs of Simmondsia chinensis

Summary Desert populations of the evergreen dioecious shrub Simmondsia chinensis exhibit sex-related leaf and canopy dimorphisms not present in populations from more mesic coastal environments. Leaves on female shrubs have characteristically larger sizes, greater specific weights, and greater water-holding capacity than male leaves in desert habitats. In coastal scrub environments no significant difference is present, with leaf characteristics of both sexes similar to those of desert male shrubs. Desert female shrub canopies are typically relatively open with little mutual branch shading. In male shrubs canopies are more densely branched with considerable mutual shading of branches. Female plants allocate a greater proportion of their vegetative resources to leaves than do male plants. Considering total biomass, male plants allocate 10–15% of their resources (biomass, calories, glucose-equivalents, nitrogen, phosphorus) to reproductive tissues. Female allocation is dependent on seed set. At 100% seed set females would allocate 30–40% of their resources to reproduction, while female reproductive investment would equal that of males at approximately 30% seed set. Sexual dimorphism and the associated physiological characteristics in Simmondsia act as an alternative to differential habitat selection by male and female plants. Female plants respond to limited water resources in desert areas by increasing their efficiency in allocating limited resources to reproductive structures.     

Races of the emperor tamarin,Saguinus imperator Goeldi (Callitrichidae,Primates)

The two described subspecies of the emperor tamarin,Saguinus imperator imperator Goeldi andSaguinus imperator subgrisescens Lönnberg are defined and compared, the geographic range of each plotted.     

Serological cross-reactivity between products of different Ia loci

Antibody prepared in I-E-subregion-incompatible strains (anti-A _e ^s :E ^/k ) cross-reacts with I-A-subregion controlled A ^b : A ^/b and A ^q A ^q complexes. This cross-reaction defines a new I-region specificity designated Ia.50. The implications of this finding for the genetic origin of the I region and immuneresponse-gene function are discussed.     

6-d-glucopyranosyl fatty acid esters from Brassica napus pollen

6-d-Glucopyranosyl esters of palmitic, oleic, linoleic and linolenic acids were identified in Brassica napus (rape) pollen. These esters are inactive as plant growth promoters in the bean second-internode bioassay.     

The sequence of the chromosomal mouse β-globin major gene: Homologies in capping,splicing and poly(A) sites

We have determined the entire nucleotide sequence of a cloned β-globin^maj gene derived from the BALB/c mouse. This sequence is 1567 bases long and includes the 5′ cap region as well as the presumptive poly(A) addition site of β-globin mRNA. The sequence establishes the fact that the gene is encoded in three discontinuous segments of DNA interrupted by two intervening sequences and precisely locates each. The smaller intervening sequence, 116 bases long, occurs between Arg and Leu codons at codon positions 30 and 31. The larger intervening sequence of 646 bases also occurs between Arg and Leu codons, but at codon positions 104 and 105. There is striking homology between the borders of the two intervening sequences, but no extensive dyad symmetry. Furthermore, the DNA region that just precedes and overlaps the 5′ cap structure of the mRNA shows homology to corresponding regions in other eucaryotic genes including the late adenovirus promoter. The 3′ untranslated sequence is closely homologous to that of the rabbit β-globin mRNA. The sequence thus allows us to identify several noncoding regions of potential importance for the expression and processing of genetic information. It also provides a basis for future comparison with other sequenced genes and a defined substrate for the development of direct tests of gene function.     

An Ly-like specificity with extensive nonlymphoid expression

The characteristics of a strong mouse alloantigen with renal, bone marrow, and lymphoid expression were studied. This antigen is probably identical to that currently designated Ly-6.2. It was defined by the high-titered (1:1000) cytotoxic activity of three different antisera against peripheral lymphocyte target cells from DBA/2, DBA/1, and a variety of other strains. In the F₂ and four backcross generations the genetic control of this specificity segregated as a single autosomal dominant gene. In lymphoid tissues the predominant expression was on T cells but 10–30% of B cells were lysed by these antisera. The specificity was expressed strongly in kidney, as shown by sequential absorption, in amounts equal to or greater than the amount in lymphoid tissues. Comparison to the rate of absorption of H-2 by kidney indicated that this antigen may be expressed in amounts comparable to an H-2 antigen in kidney. Immunization with kidney tissue resulted in a strong cytotoxic antibody response. The number of bone marrow cells expressing this antigen (40–50%) was well beyond what could be accounted for by T lymphocytes in bone marrow. In addition, a nonlymphoid tumor, the P815Y mastocytoma, was positive by cytotoxicity and by absorption. The extensive nonlymphoid expression and antigenic strength of Ly-6.2 raises the possibility that this serologically defined lymphocyte alloantigen will have histocompatibility effects when allografts of the appropriate tissues are examined.     

Rabbit muscle phosphorylase derivatives with oligosaccharides covalently bound to the glycogen storage site

Linear maltooligosaccharides, e.g., maltoheptaose or terminal 4-O-methylmaltoheptaose, activated by cyanogen bromide, react covalently with rabbit muscle phosphorylases b and a (EC 2.4.1.1). Site-specific modification prevents further binding to glycogen and shifts the phosphorylase a tetramer-dimer equilibrium in favor of the dimer. Use was made of these properties to separate by affinity chromatography and gel filtration phosphorylase a dimers with specifically bound oligosaccharide from unspecifically modified products. The phosphorylase a-maltoheptaose derivative carries one oligosaccharide residue per monomer and can be distinguished from the native enzyme by its electrophoretic mobility in polyacrylamide gels or by affinity electrophoresis. Phosphorylase a preparations with covalently bound maltooligosaccharides are enzymatically active in the presence of a primer and alpha-D-glucopyranose 1-phosphate (glucose-1-P). Methylation of the nonreducing chain terminus of the bound oligosaccharide has no effect on glycogen synthesis. These findings exclude the participation of bound oligosaccharides in chain elongation. Purified covalent phosphorylase a-maltoheptaose complexes are stable dimers. They are no longer activated by glycogen. The properties of covalently modified phosphorylase-oligosaccharides are consistent with and provide direct evidence for the existence of a glycogen storage site in rabbit muscle phosphorylases. Covalent occupation of the storage site renders the affinity of glucose-1-P to phosphorylase a independent of modulation by glycogen, supporting the assumption that the glycogen storage site is involved in interactions with the catalytic site.