Effect of plant genotype on the transformation of cultivated alfalfa (Medicago sativa) by Agrobacterium tumefaciens

The trait for somatic embryogenesis is being introduced sexually into alfalfa (Medicago sativa) breeding populations to facilitate genetic transformation of this crop. Cocultivation experiments were conducted with an agronomically-improved embryogenic clone from one such population as well as with two other embryogenic clones, one of which was the source of the embryogenic trait in the breeding populations. Transgenic plants were produced from the agronomically-improved clone whereas none were produced from the other two clones. Among the 16 transgenic plants analyzed there was a range in both copy number and number of integration sites for the NPT-II gene; those plants regenerated after a prolonged selection phase in vitro generally had the highest numbers in both respects. There was no evidence of sectoral chimerism of the transgene in a subsample of transgenic plants analyzed by PCR.     

Development and maturation of surghum seeds on detached panicles grown in vitro

Summary A procedure for culturing detached panicles of sorghum, Sorghum bicolor (L.) Moench, was developed to achieve flowering, fertilization, and subsequent seed development and maturation in vitro. Sixteen sorghum genotypes (five high and eleven low in tannin) were tested for their ability to develop normally in culture. Panicles collected one to two days before the initiation of anthesis were cultured in flasks containing liquid medium. Contamination and medium darkening were the major obstacles encountered. Up to 55% of the panicles cultured reached physiological maturity in vitro. The frequency of seed set ranged from 30 to 97% depending upon genotype and medium. Seed and glume color were normal. Seed produced in vitro resembled those grown in vivo and germinated well, but were smaller than normal (100 kernel weight reached 50 to 70% of the control). Grain polyphenols were synthesized in the cultured panicles. Seed of high tannin genotypes produced in vitro were lower in total phenols and tannins and higher in flavan-4-ols and the 3-deoxyanthocyanidin pigments than control seed. This technique can be used for harvesting late-maturing stocks and for various sorghum studies.     

In vitro modulation of antioxidant enzyme levels in normal hamster kidney and estrogen-induced hamster kidney tumor

Antioxidant enzyme (AE) activities were studied in normal hamster kidney proximal tubules and in estrogen-induced hamster kidney cancer. In vivo, kidney tumor had lower activities of manganese superoxide dismutase (MnSOD), copper, zinc superoxide dismutase, catalase, and glutathione peroxidase than kidney proximal tubules. Differences in AE activities were, in general, maintained in tissue culture, with AE activities remaining low in tumor cells compared to normal cells. Normal proximal tubular cells showed significant induction of MnSOD activity as a function of time in culture of following exposure to diethylstilbestrol, a synthetic estrogen, while MnSOD activity remained low in tumor cells under these conditions. Our results suggest that antioxidant enzymes, particularly MnSOD, are regulated differently in estrogen-induced hamster kidney tumor cells than in normal kidney proximal tubular cells, demonstrating that cancers arising from hormonal influence have similar AE profiles to those previously described in cancers arising from viral or chemical etiologies.     

Life-history traits of the lizard Sceloporus undulatus from two populations raised in a common laboratory environment

Hatchling Sceloporus undulatus elongatus from Washington Co., Utah and S. u. garmani from Woods Co., Oklahoma were raised to maturity and reproduction under identical laboratory conditions with ad libitum food availability. Growth, allometry, age and size of maturity, clutch size and egg mass were compared among lab-raised cohorts from the two populations, among lab-raised and field-caught animals (including their field-caught mothers) and, for growth, with values obtained by previously published field studies on the same or nearby populations. For all traits population differences observed in previous field studies and current field samples resulted from both a plastic response to proximate environmental conditions and intrinsic (possibly genetic) difference. The most plastic traits were growth and age of maturity. Cohorts from both populations expressed the ability to mature in less than 6 months in the laboratory but only the S.u. garmani express early maturity in the field. Allometric differences generated during growth in the lab were not observed in field samples but may reflect an adaptive physiological difference. The least plastic trait was egg mass. The only trait for which the rank order of the difference in the field was reversed in the lab was growth rate. S.u. elongatus grew significantly faster than S.u. garmani in the lab but much slower in the field. The tendency of S.u. garmani females to breed at minimum size of maturity may be greater than that of S.u. elongatus.     

Proteolytic processing of the vitellogenin precursor in the boll weevil,Anthonomus grandis

The soluble proteins of the eggs of the coleopteran insect Anthonomus grandis Boheman, the cotton boll weevil, consist almost entirely of two vitellin types with M_rs of 160,000 and 47,000. We sequenced their N-terminal ends and one internal cyanogen bromide fragment of the large vitellin and compared these sequences with the deduced amino acid sequence from the vitellogenin gene. The results suggest that both the boll weevil vitellin proteins are products of the proteolytic cleavage of a single precursor protein. The smaller 47,000 M vitellin protein is derived from the N-terminal portion of the precursor adjacent to an 18 amino acid signal peptide. The cleavage site between the large and small vitellins at amino acid 362 is adjacent to a pentapeptide sequence containing two pairs of arginine residues. Comparison of the boll weevil sequences with limited known sequences from the single 180,000 M_r honey bee protein show that the honey bee vitellin N-terminal exhibits sequence homology to the N-terminal of the 47,000 M_r boll weevil vitellin. Treatment of the vitellins with an N-glycosidase results in a decrease in molecular weight of both proteins, from 47,000 to 39,000 and from 160,000 to 145,000, indicating that about 10–15% of the molecular weight of each vitellin consists of N-linked carbohydrate. The molecular weight of the deglycosylated large vitellin is smaller than that predicted from the gene sequence, indicating possible further proteolytic processing at the C-terminal of that protein. © 1993 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Oxide-Based Solid-State Batteries: A Perspective on Composite Cathode Architecture

The garnet-type phase Li₇La₃Zr₂O₁₂ (LLZO) attracts significant attention as an oxide solid electrolyte to enable safe and robust solid-state batteries (SSBs) with potentially high energy density. However, while significant progress has been made in demonstrating compatibility with Li metal, integrating LLZO into composite cathodes remains a challenge. The current perspective focuses on the critical issues that need to be addressed to achieve the ultimate goal of an all-solid-state LLZO-based battery that delivers safety, durability, and pack-level performance characteristics that are unobtainable with state-of-the-art Li-ion batteries. This perspective complements existing reviews of solid/solid interfaces with more emphasis on understanding numerous homo- and heteroionic interfaces in a pure oxide-based SSB and the various phenomena that accompany the evolution of the chemical, electrochemical, structural, morphological, and mechanical properties of those interfaces during processing and operation. Finally, the insights gained from a comprehensive literature survey of LLZO–cathode interfaces are used to guide efforts for the development of LLZO-based SSBs.     

The effectiveness of sodium lauryl sulphate as a shark repellent in a laboratory test situation

Swim-through chemical repellency tests, using sodium lauryl sulphate (SLS), cupric acetate, and rotenone, were conducted in a specially-designed roundabout tank on horn sharks, Heterodontus francisci , swell sharks, Cephaloscylliun ventriosum , and leopard sharks, Triakis semifasciata . Effective concentration thresholds (EC₅₀s) were calculated for two levels of response: (1) minimum noticeable and (2) strong. The SLS EC₅₀s were: horn shark 43.6 and 174.5 ppm; swell shark 95.1 and 160.0 ppm; and leopard shark inconclusive and 113.1 ppm. No response was discernible from cupric acetate. Rotenone evoked a weak response with an EC₅₀ of 5.7 ppm, but no strong response.
The ratio of the minimum noticeable EC₅₀: 24-hour lethal concentration (LC₅₀) indicated the relative repellency (compared to toxicity) of the chemicals. The ratio for SLS was 19:1 and for rotenone 57:1. SLS did not provoke a repellency response at a low enough concentration to function effectively as a classical, surrounding-cloud type, repellent. The range of potency of SLS, however, does allow it to be used as a directional repellent.     

SYSTEMATIC ANALYSIS OF SPHAEROPLEA (CHLOROPHYCEAE)1

A systematic investigation of the genus Sphaeroplea was conducted using cladistic analyses of both structural and isozyme characters for the same set of taxa. The structural data were not able to fully resolve some of the taxa while the isozyme data did produce a tree in which all nodes were supported by data. The structural characters were relatively consistent with one another, whereas the isozyme characters were much less internally consistent. Results from independent, cladistic analyses of both data sets support the concept that among those Sphaeroplea species investigated, S. fragilis Buchheim et Hoffman had an early divergence. The two data sets differed primarily in that the structural data support monophyly of the genus Sphaeroplea and the isozyme data do not. The greater relative consistency of the structural data suggests better support for trees inferred from its analysis. Furthermore, searches for character congruence between the two data sets revealed isozyme data which support monophyly of the genus Sphaeroplea, but had been overwhelmed by conflicting isozyme characters.     

The cardiac Na-H exchanger: a key downstream mediator for the cellular hypertrophic effects of paracrine, autocrine and hormonal factors.

The major mechanism by which the heart cell regulates intracellular pH is the Na(+)-H(+) exchanger (NHE) with the NHE-1 isoform as the primary cardiac subtype. Although NHE-1 has been implicated in mediating ischemic injury, more recent evidence implicates the antiporter as a key mediator of hypertrophy, which is produced by various autocrine, paracrine and hormonal factors such as endothelin-1, angiotensin II, and alpha(1) adrenoceptor agonists. These agonists activate the antiporter via phosphorylation-dependent processes. NHE-1 inhibition is likely conducive to attenuating the remodelling process after myocardial infarction. These effects probably occur independently of infarct size reduction and involve attenuation of subsequent postinfarction heart failure. As such, inhibitors of NHE offer substantial promise for clinical development that will attenuate acute responses to myocardial postinfarction and chronic pos t infarction, which evolve toward heart failure. The regulation of NHE-1 is discussed as is its potential role in mediating cardiomyocyte hypertrophy.     

Ingestion of Salmonella enterica Serotype Poona by a Free-Living Nematode, Caenorhabditis elegans, and Protection against Inactivation by Produce Sanitizers

Free-living nematodes are known to ingest food-borne pathogens and may serve as vectors to contaminate preharvest fruits and vegetables. Caenorhabditis elegans was selected as a model to study the effectiveness of sanitizers in killing Salmonella enterica serotype Poona ingested by free-living nematodes. Aqueous suspensions of adult worms that had fed on S. enterica serotype Poona were treated with produce sanitizers. Treatment with 20 μg of free chlorine/ml significantly (α = 0.05) reduced the population of S. enterica serotype Poona compared to results for treating worms with water (control). However, there was no significant difference in the number of S. enterica serotype Poona cells surviving treatments with 20 to 500 μg of chlorine/ml, suggesting that reductions caused by treatment with 20 μg of chlorine/ml resulted from inactivation of S. enterica serotype Poona on the surface of C. elegans but not cells protected by the worm cuticle after ingestion. Treatment with Sanova (850 or 1,200 μg/ml), an acidified sodium chlorite sanitizer, caused reductions of 5.74 and 6.34 log₁₀ CFU/worm, respectively, compared to reductions from treating worms with water. Treatment with 20 or 40 μg of Tsunami 200/ml, a peroxyacetic acid-based sanitizer, resulted in reductions of 4.83 and 5.34 log₁₀ CFU/worm, respectively, compared to numbers detected on or in worms treated with water. Among the organic acids evaluated at a concentration of 2%, acetic acid was the least effective in killing S. enterica serotype Poona and lactic acid was the most effective. Treatment with up to 500 μg of chlorine/ml, 1% hydrogen peroxide, 2,550 μg of Sanova/ml, 40 μg of Tsunami 200/ml, or 2% acetic, citric, or lactic acid had no effect on the viability or reproductive behavior of C. elegans. Treatments were also applied to cantaloupe rind and lettuce inoculated with S. enterica serotype Poona or C. elegans that had ingested S. enterica serotype Poona. Protection of ingested S. enterica serotype Poona against sanitizers applied to cantaloupe was not evident; however, ingestion afforded protection of the pathogen on lettuce. These results indicate that S. enterica serotype Poona ingested by C. elegans may be protected against treatment with chlorine and other sanitizers, although the basis for this protection remains unclear.