The response of a bumblebee goby,Brachygobius sabanus,to chemical stimuli from injured conspecifics

Synopsis Brachygobius sabanus move less often and spend less time swimming when they detect chemicals released from injured conspecifics. This resembles the alarm response found in ostariophysan fishes, darters, and at least one other gobiid. Chemicals from injured Poecilia reticulata do not induce an alarm response in B. sabanus.     

Photographic densitometry for quantitative DNA analysis of cytologic and histologic specimens.

We found that photographic densitometry (PD) is a useful technique for quantitative determinations of nuclear DNA content in clinical tumor material. Optimum conditions for the use of PD in clinical cytology and histopathology were worked out. A quantitative evaluation of the method was performed, particularly with respect to errors that may appear when measuring clinical tumor material. Our study showed that PD offers accurate DNA measurements in cytologic and histologic specimens. Ploidy level determinations in tumor cell populations in clinical material could be as accurately performed with PD as with scanning microspectrophotometry (SMP). Nuclear DNA content of individual cells as determined by PD correlated highly with nuclear DNA content determined by SMP (correlation coefficient, 0.96). Since the PD method is less influenced by background variation than are other image techniques (due to measurement of a photographic image), it is particularly useful in measurement of histopathologic sections, in which the background variation can introduce considerable errors. The method is also valuable with clinical cytologic smears, in which the presence of blood and other material disturbs the background. PD represents a valid complement to scanning microspectrophotometry and TV imaging systems, particularly for DNA analysis of tissue sections. Moreover, it can be applied easily in the clinical routine. Relevant tissue areas are selected and photographed by the pathologist or cytopathologist, and the measurement is performed by a laboratory technician.     

Structural requirements for high affinity ligand binding by estrogen receptors: a comparative analysis of truncated and full length estrogen receptors expressed in bacteria, yeast, and mammalian cells.

In order to better understand the structural requirements for effective high affinity binding of estrogens and antiestrogens by the human estrogen receptor (ER), a comparative study was undertaken in which we examined: 1) native ER from the MCF-7 ER-positive human breast cancer cell line; 2) full length ER expressed in yeast; 3) the ER hormone binding domain (amino acid residues 302-595) expressed in yeast; 4) a bacterially expressed protein A fusion product encoding a truncated ER (amino acid residues 240-595); and 5) a synthetic peptide encompassing amino acids 510-551 of the ER. The binding parameters studied included affinity, kinetics, structural specificity for ligands, and stability. Full length ER expressed in yeast was very similar to the MCF-7 ER in its affinity [dissociation constant (Kd), 0.35 +/- 0.05 nM], dissociation rate (t1/2, 3-4 h at 25 C), and structural specificity for both reversible and covalently attaching affinity ligands. While the truncated ER expressed in yeast was similar to MCF-7 ER in its specificity of ligand binding, it showed a slightly reduced affinity for estradiol (Kd, 1.00 +/- 0.17 nM). The bacterially expressed ER also had a lower affinity for estradiol (Kd, 1.49 +/- 0.16 nM), which may be due in part to an increase in the dissociation rate (t1/2, 0.5 h at 25 C). The attachment of covalent affinity ligands and structural specificity for a variety of reversible ligands was comparable in the bacterially expressed ER to that observed for the receptors expressed in MCF-7 cells and yeast.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased yield of fructose from glucose employing thermophilic xylose isomerase in water-ethanol mixtures

Summary The isomerization of D-glucose in mixed ethanol-water was studied at various reaction temperatures (40–70 °C), employing glucose isomerase fromStreptomyces phaeochromogenes andClostridium thermohydrosulfuricum, respectively. The thermophilicClostridium enzyme was considerably, more stable towards the combination of organic cosolvent and increased temperature and with this enzyme a 55% yield of fructose from glucose was obtained at relatively low concentration of ethanol (40 %).     

Rapid and simple isolation of pure photosystem II core and reaction center particles from spinach

Pure and active oxygen-evolving PS II core particles containing 35 Chl per reaction center were isolated with 75% yield from spinach PS II membrane fragments by incubation with n-dodecyl--D-maltoside and a rapid one step anion-exchange separation. By Triton X-100 treatment on the column these particles could be converted with 55% yield to pure and active PS II reaction center particles, which contained 6 Chl per reaction center.Abbreviations Bis-Tris bis[2-hydroxyethyl]imino-tris[hydroxymethyl]methane - Chl chlorophyll - CP29 Chl a/b protein of 29 kDa - Cyt b ₅₅₉ cytochrome b ₅₅₉ - DCBQ 2,5-dichloro-p-benzo-quinone - LHC II light-harvesting complex II, predominant Chl a/b protein - MES 2-[N-Morpholino]ethanesulfonic acid - Pheo pheophytin - PS H photosystem II - Q_A bound plastoquinone, serving as the secondary electron acceptor in PS II (after Pheo) - SDS sodiumdodecylsulfate     

The AXB and BXA set of recombinant inbred mouse strains

The recombinant inbred (RI) set of strains, AXB and BXA, derived from C57BL/6J and A/J, originally constructed and maintained at the University of California/San Diego, have been imported into The Jackson Laboratory and are now in the 29th to 59th generation of brother-sister matings. Genetic quality control testing with 45 proviral and 11 biochemical markers previously typed in this RI set indicated that five strains had been genetically contaminated sometime in the past, so these strains have been discarded. The correct and complete strain distribution patterns for 56 genetic markers are reported for the remaining RI strain set, which consists of 31 living strains and 8 extinct strains for which DNA is available. Two additional strains, AXB 12 and BXA 17, are living and may be added to the set pending further tests of genetic purity. The progenitors of this RI set differ in susceptibility to 27 infectious diseases as well as atherosclerosis, obesity, diabetes, cancer, cleft palate, and hydrocephalus. Thus, the AXB and BXA set of RI strains will be useful in the genetic analysis of several complex diseases.     

Molecular analysis of the avirulence gene avr9 of the fungal tomato pathogen Cladosporium fulvum fully supports the gene-for-gene hypothesis

The interaction between the fungal pathogen Cladosporium fulvum and tomato is supposed to have a gene-for-gene basis. Races of C. fulvum which have 'overcome' the resistance gene Cf9 of tomato, lack the avirulence gene avr9 which encodes a race-specific peptide elicitor. Races avirulent on tomato genotypes carrying the resistance gene Cf9 produce the race-specific peptide elicitor, which induces the hypersensitive response (HR) on those genotypes. The causal relationship between the presence of a functional avr9 gene and avirulence on tomato genotype Cf9 was demonstrated by cloning of the avr9 gene and subsequent transformation of C. fulvum. A race virulent on tomato genotype Cf9 was shown to become avirulent by transformation with the cloned avr9 gene. These results clearly demonstrate that the avr9 gene is responsible for cultivar specificity on tomato genotype Cf9 and fully support the gene-for-gene hypothesis. The avr9 gene is the first fungal avirulence gene to be cloned.     

Presence of corazonin in three insect species, and isolation and identification of [His7]corazonin from Schistocerca americana.

An ELISA for corazonin, a cardioactive neuropeptide from the American cockroach, Periplaneta americana, was developed. It was used to isolate corazonin from the cockroach Nauphoeta cinerea, the locust Schistocerca americana, and the hawkmoth Manduca sexta. The peptides from Nauphoeta and Manduca had the same retention times as Periplaneta corazonin, and their amino acid compositions also suggested that these peptides are identical with corazonin. The corazonin-immunoreactive peptide from Schistocerca eluted slightly earlier on HPLC than corazonin, and its structure was determined to be [His⁷]corazonin, or pGlu-Thr-Phe-Gln-Tyr-Ser-His-Gly-Trp-Thr-Asn-amide. These results indicate that corazonin is generally present in insects and that its structure has been well conserved.     

Human pheochromocytoma cells studied in culture contain large amounts of DSIP-like material.

Delta sleep-inducing peptide (DSIP)-like immunoreactive (LI) material has been detected in nine different human pheochromocytoma tumors by immunocytochemistry. In primary tumors subjected to indirect immunofluorescence a variable number of tumor cells (25-75%) showed positive cytoplasmic labeling after incubation with DSIP antiserum. Tumor cells grown in culture were strongly labeled by the DSIP antiserum with DSIP-LI concentrated to cell bodies. Electron microscopic immunocytochemistry (immunogold labeling) of pheochromocytoma cells demonstrated DSIP-LI over the dense core of secretory granules. The presence of DSIP-LI in several HPLC fractions from conditioned culture media indicates secretion of DSIP-LI from cultured pheochromocytoma cells. The observations suggest that DSIP-LI is synthesized and stored in secretory granules before release. The different HPLC profiles from each of the tumors may reflect differences in processing or turnover of DSIP-LI in pheochromocytoma cells.