Sharp intense line in the bioluminescence emission of the firefly

Numerous investigations have been carried out on the spectral distribution of the light of different species of fireflies. Here we record the emission spectrum of the Indian species of the firefly Luciola praeusta Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae) on a color film. Green and red color-sectors, with an intense yellow one in between, appear in this spectrum. Intensity profile of this spectrum reveals a hitherto undetected strong narrow yellow line, which lies within the full-width-at-half maximum (FWHM) of the intensity profile. The spectrum recorded in a high-resolution spectrometer confirms the presence of this sharp intense line. This finding lends support to an earlier drawn analogy between the in vivo emission of the firefly and laser light.     

Betulachrysoquinone hemiketal: A p-benzoquinone hemiketal macrocyclic compound produced by Phanerochaete chrysosporium

Betulachrysoquinone hemiketal was isolated from pre-extracted wood of Betula lutea Michx. inoculated with Phanerochaete chrysosporium Burds. Acid-catalysed hydrolysis of betulachrysoquinone hemiketal produced betulachrysoquinone which was shown to be 2-hydroxy-6-(13′-hydroxytetradecanyl)-p-benzoquinone.     

AFDX-116 discriminates between muscarinic M2 receptors of the heart and the iris smooth muscle

Summary Studies with the atypical muscarinic antagonist pirenzepine provide convincing evidence for the classification of muscarinic acetylcholine receptors (mAChRs) into two subtypes, M₁ and M₂. The present study examines the heterogeneity of the M₂ subtype employing the newly developed competitive muscarinic antagonist, AFDX-116. Comparison of the binding affinities of pirenzepine, atropine, and AFDX-116 to mAChRs in microsomes from the rabbit cerebral cortex, heart, and iris smooth muscle shows that iris mAChRs, which are pharmacologically of the M₂ subtype, can be distinguished from M₂ cardiac receptors based on their affinity for AFDX-116. These results are consistent with the hypothesis that the M₂ receptor subtype consists of a heterogeneous population of receptors.Abbreviations mAChRs Muscarinic Acetylcholine Receptors - CCh Carbachol - NMS N-Methylscopolamine - AFDX-116 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6Hpyrido[2,3-b][1,4]benzodiazepine-6-one     

Epidermal conductance in different parts of durum wheat grown under Mediterranean conditions: the role of epicuticular waxes and stomata

Abstract. Epidermal (non-stomatally-controlled) conductance from the fourth leaf, first node leaf, flag leaf and ear of durum wheat (Triticum turgidum var durum L.) grown under Mediterranean field conditions has been measured, along with leaf stomatal frequency and the amount and distribution of epicuticular waxes. Measurements were carried out on varieties and land-races from the Middle East, North Africa, ‘Institut National de la Recherche Agricole’ (INRA) and ‘Centra Internacional de Mejora de Maiz y Trigo’ (CIMMYT). Significant differences were observed among genotypes in the epidermal conductances (g_e) of the four organs. For each of the four organs tested, genotypes from the Middle East and CIMMYT showed higher g_e. values than those from North Africa and INRA. Ears showed epidermal conductances that were more than four times higher than those of leaves when g_e. values were expressed per unit dry weight. The amount of epicuticular waxes was higher in the fourth leaves, intermediate in the first node and flag leaves and lower in the ears. For each organ, g_e differences among genotypes were unrelated with the amount of epicuticular waxes. Removal of epicuticular waxes by dipping the organs into chloroform significantly increased the epidermal conductance for the fourth and first node leaves and the ear. However, this did not occur for the flag leaf. For the fourth leaf, g_e of intact leaves and g_e of leaves in which epicuticular waxes were removed were unrelated (r = -0.265). The regression coefficient of this relation for the first node and flag leaves showed values of 0.666 and 0.650 (P > 0.05), respectively, and values were even higher in the ear (r > m 0.892, P > 0.01). Scanning electron microscope analysis showed that wax bloom decreased from the fourth leaf to the flag leaf, whereas the extent of amorphous wax increased. Wax bloom in leaves consisted mainly of deposits of thin wax plates. In the ears and the adaxial surface of flag leaves, fibrillar waxes predominated. In the first node and flag leaves, the wax deposits on the adaxial side cover the surface of the leaf more densely and uniformly than those on the abaxial side. There was no significant correlation between g_e and total stomatal density, or between g_e and either adaxial or abaxial stomatal density for any sample of the three different leaves. The contribution of epicuticular waxes plus total stomatal frequency only explained 42.4, 11.8, 28.3 and 16% of g_e (per unit leaf area) variations for the fourth leaf, first node leaf, flag leaf and the combined variation of the three leaves together, respectively. From these results, it is concluded that complex interrelationship between different morphophysiological characteristics probably control g_e differences among genotypes and that these interrelationships differ for each different plant part.     

Cellular systems for the study of the biosynthesis of polyamines and ethylene,as well as of virus multiplication

Leaves of Chinese cabbage from healthy plants or from those infected with turnip yellow mosaic virus yield protoplasts which convert methionine to protein, S-adenosylmethionine, decarboxylated S-adenosylmethionine, spermidine, spermine and 1-aminocyclopropane-1-carboxylate. The enzyme spermidine synthase is entirely cytosolic and has been purified extensively. An inhibitor of this enzyme, dicyclohexylamine, blocks spermidine synthesis in intact protoplasts, and in so doing stimulates spermine synthesis. Aminoethoxyvinylglycine blocks the conversion of S-adenosylmethionine to 1-aminocyclopropane-1-carboxylate, the precursor to ethylene, in protoplasts. This inhibitor markedly stimulates the synthesis of both spermidine and spermine. Essentially all the protoplasts obtained from new leaves of plants infected 7 days earlier are infected. On incubation, such protoplasts convert exogenous methionine to viral protein and viral spermidine whose specific radioactivity is twice that of total cell spermidine. Exogeneous spermidine is also converted to cell putrescine and viral spermidine and spermine. Normal and virus-infected cells are being studied for their content of phenolic acid amides of the polyamines.     

Linkage mapping of genes for resistance to leaf,stem and stripe rusts and ω-secalins on the short arm of rye chromosome 1R

Summary The genes controlling resistance to three wheat rusts, viz., leaf rust (Lr26), stem rust (Sr31) and stripe or yellow rust (Yr9), and -secalins (Sec1), located on the short arm of rye chromosome 1R, were mapped with respect to each other and the centromere. Analysis of 214 seeds (or families derived from them) from testcrosses between a 1BL.1RS/1R heterozygote and Chinese Spring ditelocentric 1BL showed no recombination between the genes for resistance to the three rusts, suggesting very tight linkage or perhaps a single complex locus conferring resistance to the three rusts. The rust resistance genes were located 5.4 ± 1.7 cM from the Sec1 locus, which in turn was located 26.1 ± 4.3 cM from the centromere; the gene order being centromere — Sec1 — Lr26/Sr31/Yr9 — telomere. In a second test-cross, using a different 1BL.1RS translocation which had only stem rust resistance (SrR), the above gene order was confirmed despite a very large proportion of aneuploids (45.8%) among the progeny. Furthermore, a map distance of 16.0 ± 4.8 cM was estimated for SrR and the telomeric heterochromatin (C-band) on 1RS. These results suggest that a very small segment of 1RS chromatin is required to maintain resistance to all three wheat rusts. It should be possible but difficult to separate the rust resistance genes from the secalin gene(s), which are thought to contribute to dough stickiness of wheat-rye translocation lines carrying 1RS.     

Effect of increased CO2 concentration and temperature on the phyllosphere mycoflora of winter wheat flag leaves during ripening

The impact of elevated carbon dioxide (CO₂, 600/700 μmol mol^-1) and temperature (+ 4°C) on phyllosphere fungi colonising flag leaves of mini crops of winter wheat cv. Mercia between anthesis and harvest was determined in a computer-controlled environment facility in 1993 and 1994. In both years the total fungal populations (cm² leaf) were found to have increased due to exposure to either elevated CO₂ and elevated CO₂+ temperature treatments. This was mainly due to significant increases in populations of Cladosporium spp. (C. cladosporioides and C. herbarum) on the flag leaves during ripening. Other phyllosphere component species such as white and pink yeasts were not markedly affected by treatments. The range of fungal species found in such controlled environment chambers was narrower than that commonly found on flag leaves of field grown crops. Common and important colonisers of leaves and ripening ears such as Aureobasidium pullulans, Epicoccum nigrum and Fusarium spp. were seldom isolated.     

Spread of beet necrotic yellow vein virus in infected seedlings and plants of sugar beet (Beta vulgaris)

Summary Infection of sugar beet roots by beet necrotic yellow vein virus (BNYVV) was investigated with transmission electron microscopy, immunogold labelling and enzyme linked immuno sorbent assay (ELISA). Here we show that infection of sugar beet roots is very fast, occurring during germination. Seedlings grown directly in infected soil showed higher BNYVV infection than plants transplanted into infected soil after seven days of initial growth in sterilized soil. The earlier the initial infection, the faster was its spread. The study showed that a few differentiated cells of the cortex and of the xylem parenchyma were the preferred sites of viral multiplication. The spread of viral infection was slow through differentiated tissues. Intact virions were frequently found in undifferentiated and mature vessel elements and xylem parenchyma, whereas they were rare in sieve elements. Virus particle number in the differentiating tracheary elements was high, suggesting that infection of the vessel elements preceded their differentiation. This would explain increased infection after early inoculation. Even the xylem tissue of the primary root was highly infected, the seedlings lacked virus particles in their hypocotyls and leaves.     

Distribution of the enantiomers of hydroxychloroquine and its metabolites in ocular tissues of the rabbit after oral administration of racemic-hydroxychloroquine

The disposition of the enantiomers of hydroxychloroquine (HCQ) and its major metabolites in ocular tissues of rabbits has been studied. Both albino, New Zealand White (NZW), and pigmented animals were administered daily oral doses of rac-HCQ, (S)-HCQ or (R)-HCQ (20 mg/kg) over 1, 6, or 8 day periods or for 8 days followed by a 7-day washout period. At the end of the study periods, plasma and whole blood samples were collected and the rabbits were sacrificed. The eyes were collected, the aqueous humor removed with a syringe, and the eyes separated into the cornea, lens, vitreous body, iris, choroid-retina, sclera, and conjunctiva. The concentrations of (R)-HCQ, (S)-HCQ, and their respective metabolites were determined using a validated enantioselective liquid chromatographic assay. The data from these studies indicate that HCQ accumulated in both pigmented and nonpigmented ocular tissues. In the pigmented tissues, HCQ and its metabolites were bound to melanin and the binding was not enantiospecific. In the nonpigmented tissues and in the iris and retina-choroid of the NZW rabbits, the accumulation appeared to be the result of a reversible and enantioselective binding of HCQ and its metabolites to an unidentified biopolymer present in these ocular tissues. © 1994 Wiley-liss, Inc.