Photoengraving of coverslips and slides to facilitate monitoring of micromanipulated cells or chromosome spreads

A simple photolithographic technique has been developed which can be used to produce microscopic grid patterns on glass coverslips. The grid pattern is first photo-reduced onto film, and the resulting photographic negative is then used as a mask. A glass slide or coverslip, coated with a layer of photoresist, is then exposed to tungsten light through the mask. After developing and etching, the grid pattern is transferred permanently onto glass. This simple and rapid procedure allows one to mass-produce very small, high resolution grids which are useful for monitoring individual microinjected cells or chromosomal spreads under the microscope.     

Effect of food limitation on food consumption and reproductive allocation by adult milkweed bugs, Oncopeltus fasciatus

Male/female pairs of adult milkweed bugs, Oncopeltus faciatus were offered reduced food rations (100 mg milkweed seeds/week, 50 mg seeds/week, and 25 mg seeds/week) at 232C, 14L : 10D photoperiod. The high rate of food consumption normally occurring during the teneral period (first 8 days posteclosion) and subsequent food consumption were reduced on both reduced rations. Initial fresh weight was lost by bugs on both reduced rations and their weekly fresh body weight tended to remain less than bugs on the 100 mg seeds/week ration.Normal onset of egg production (about 3 weeks posteclosion) was delayed 6 weeks and normal length of a female's life (13–14 weeks) was increased 7–8 weeks on the 25 mg seeds/week ration. Rate of egg production exhibited a linear decrease with decrease in food ration on both reduced rations due to an increased interclutch interval, while fresh egg weight, duration of egg stage, number of eggs/clutch and percentage of clutches containing fertile eggs were little affected.Gross egg production efficiency (efficiency of conversion of ingested food into eggs = dry mg egg production × 100/dry mg food ingested) was high on both the 100 and 50 mg seeds/week rations (27.9% and 21.1%, respectively) and low (7.7%) on the 25 mg seeds/week ration. These data are discussed in the context of the reciprocal interaction between nutrient intake and egg production.     

Flavonoid chemistry of arceuthobium (viscaceae)

Flavonoid compounds from 36 of the 38 known taxa of the genusArceuthobium (dwarf mistletoes) were examined. The flavonoid chemistry of the genus is rather uniform, all taxa producing 3-O-glycosides of the flavonols quercetin and myricetin. No infraspecific chemical variation was encountered, and in those instances where subspecific taxa are recognized, their chemistry was uniform. At the subgeneric level, members of subgenusArceuthobium synthesize primarily glucosides, whereas galactosides are more common in subgenusVaginata. In two of the four Old World species of subgenusArceuthobium (A. juniperi- procerae andA. oxycedri) only myricetin 3-O-glucoside was detected. There are no absolute flavonoid differences between subgenera, sections, or series. On the other hand, flavonoids are useful in several instances at the species level. In several cases, chemical data lend support to the recognition of species which in the past have been considered doubtfully distinct on the basis of morphology.     

A general procedure for the preparation of labeled l-ascorbic acid from labeled d-glucose

A simple, three-step conversion of 1,2-O-isopropylidene-α-d-glucofuranose into l-ascorbic acid, originally described by Bakke and Theander, was used to prepare l-[4-¹⁴C]ascorbic acid from milligram amounts of d-[3-¹⁴C]glucopyranose in 28% radioisotopic yield. In addition, l-[6-¹⁴C]- and l-[U-¹⁴C]-ascorbic acid were prepared from d-[1-¹⁴C]- and d-[U-¹⁴C]-glucopyranose, respectively. The procedure is useful for the synthesis of l-ascorbic acid bearing isotopic hydrogen, carbon, or oxygen atoms at specific positions, subject only to the availability of starting material.     

Linkage of the gene controlling the synthesis of the fourth component of complement to the major histocompatibility complex of the guinea pig

C4-deficient (C4D) guinea pigs are lacking in C4 synthesis, a condition that appears to be caused by a structural gene defect. This defect is inherited as a simple autosomal recessive trait. We have demonstrated linkage between C4D and the major histocompatibility complex of the guinea pig (GPLA). Inbred C4D and inbred strain 13 guinea pigs appear to have the same GPLA haplotype. The use of these two strains should provide an animal model for reconstitution studies of C4 synthesis and for studied exploring the possible role of C4 in cellular and humoral immune responses.Abbreviations used in this paper are C4D deficiency of the fourth component of complement - MHC major histocompatibility complex - GPLA major histocompatibility complex of the guinea pig - MLC mixed lymphocyte culture     

Improved chemical synthesis and enzymatic assay of delta-1-pyrroline-5-carboxylic acid.

Δ¹-Pyrroline-5-car?ylic acid, an intermediate in both the biosynthesis and degradation ofl-proline, has been synthesized by the periodate oxidation of hydroxylysine and isolated as a pure compound, as indicated by enzymatic assay with pyrroline-5-car?ylate reductase fromEscherichia coli. Some features of the instability in solution ofΔ¹-pyrroline-5-car?ylic acid have been studied, leading to the conclusion that the rate of decomposition is sensitive to concentration of the compound. Colorimetric assay witho-aminobenzaldehyde was found to be an inadequate measure of the pyrroline compound in partially decomposed solutions.     

Dispersal polymorphisms in subdivided populations

Price's method for analyzing natural selection in subdivided populations is applied to the problem of dispersal polymorphism strategies in a stable habitat. The results agree with the more traditional Mendelian models for this same problem that have recently been published. Further, by using Price's method, the results obtained are simpler and more general, and the causal evolutionary mechanisms underlying the predicted patterns are more easily recognized. The most interesting new result is that the equilibrium proportion of dispersed individuals is a simple function of the risk of dispersing and the regression coefficient of relatedness among individuals who, in the absence of dispersal, would compete for a limited, local resource. This regression coefficient refers to the genotypes that control the dispersal phenotype. For example, when mothers control the phenotype of their progeny, then the regression is from the mother onto an offspring chosen randomly from the local group before dispersal; while when offspring control their own phenotype, the regression is taken directly from offspring onto a randomly chosen cohort member before dispersal. This use of controlling genotypes to calculate regressions explains the form of the parent-offspring conflict over dispersal noted by previous authors. The simplicity and generality of these results suggest that Price's method is a useful approach for studying the class of phenomena known as "games among relatives".     

Effect of apolipoprotein A-I lipidation on the formation and function of pre-beta and alpha-migrating LpA-I particles

A unique class of lipid-poor high-density lipoprotein, pre-beta1 HDL, has been identified and shown to have distinct functional characteristics associated with intravascular cholesterol transport. In this study we have characterized the structure/function properties of poorly lipidated HDL particles and the factors that mediate their conversion into multimolecular lipoprotein particles. Studies were undertaken with homogeneous recombinant HDL particles (LpA-I) containing apolipoprotein (apo) A-I and various amounts of palmitoyloleoylphosphatidylcholine (PC) and cholesterol. Complexation of apoA-I with small amounts of PC and cholesterol results in the formation of discrete lipoprotein structures that have a hydrated diameter of about 6 nm but contain only one molecule of apoA-I (Lp1A-I). While the molecular charge and alpha-helix content of apoA-I are unaffected by lipidation, the thermodynamic stability of the protein is reduced significantly (from 2.4 to 0.9 kcal/mol of apoA-I). Evaluation of apoA-I conformation by competitive radioimmunoassay with monoclonal antibodies shows that addition of small amounts of PC and cholesterol to apoA-I significantly increases the immunoreactivity of a number of domains over the entire molecule. Increasing the ratio of PC:apoA-I to 10:1 in the Lp1A-I complex is associated with increases in the alpha-helix content and stability of apoA-I. However, incorporation of 10-15 mol of PC destabilizes the Lp1A-I complex and promotes the formation of more thermodynamically stable (1.8 kcal/mol of apoA-I) bimolecular structures (Lp2A-I) that are approximately 8 nm in diameter. The formation of an Lp2A-I particle is associated with an increased immunoreactivity of most of the epitopes studied, with the exception of one central domain (residues 98-121), which becomes significantly less exposed. This structural change parallels a significant increase in the net negative charge on the complex. Characterization of the ability of these lipoproteins to act as substrates for lecithin:cholesterol acyltransferase (LCAT) shows that unstable Lp1A-I complexes stimulate a higher rate of cholesterol esterification by LCAT than the small but more stable Lp2A-I particles (Vmax values are 5.8 and 0.3 nmol of free cholesterol esterified/h, respectively). The ability of LCAT to interact with lipid-poor apoA-I suggests that LCAT does not need to bind to the lipid interface on an HDL particle but that LCAT may directly interact with apoA-I. The data suggests that lipid-poor HDL particles may be metabolically reactive particles because they are thermodynamically unstable.