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71.
72.
Olfactory sensitivity in tsetse flies: a daily rhythm 总被引:3,自引:0,他引:3
The diurnal tsetse Glossina morsitans morsitans bites especially in early
morning and late afternoon; around midday feeding is at a low. In
laboratory apparatus that measures the amount of locomotion under constant
conditions over the photophase, the flies display a similar patterning of
activity levels. The profile of daily rhythms for G. morsitans reported in
the literature includes a number of motor and sensory motor systems that
fluctuate cophasically. Lacking is a study on the patterning of the senses'
response levels. In this paper we present the first instance of a daily
modulation in the sense of smell. We stimulated the antennae with
concentration series of host-derived odours and measured the spiking rate
of cells at different times during the photophase. The
concentration-response curves suggest that the sensitivity of antennal
olfactory cells flows in parallel with the other daily rhythms. This was
also reflected in electroantennograms (EAGs). The electroantennography was
extended to G. fuscipes fuscipes, whose level of spontaneous locomotor
activity--instead of following a U- shaped pattern--rises gradually over
the photophase. Again, the EAGs appeared to parallel the species' locomotor
activity. What we believe happens is that the organism tones down the
sensitivity of its odour receptors during periods of anticipated inactivity
for reasons of economy.
相似文献
73.
The cysteine proteinase 1 (CP1) and cysteine proteinase 2 (CP2) genes of Dictyostelium discoideum encode co-ordinately expressed mRNA sequences which are inducible by extracellular cAMP. There are short, G-rich sequence elements upstream of both genes and we have previously shown that deletion of these elements from the CP2 gene abolishes cAMP-inducibility. We show here that the G-rich element from the CP1 gene is functionally homologous to that in the CP2 gene by reconstituting cAMP-inducibility in a deletion mutant of the CP2 gene using CP1-derived sequences. Both the CP1 and CP2 genes contain multiple G-rich elements. We show that efficient induction requires at least two copies of the CP1 element and that their relative orientation is unimportant. Two copies of an inverted relative orientation are, however, inactive when moved upstream of their normal position and are incapable of conferring cAMP-inducibility on a heterologous gene. These observations suggest that these sequences are either essential promoter elements, not themselves interacting with the inducer, or that their interaction with a separate class of control sequences is necessary for inducible expression. 相似文献
74.
75.
Background
Bacterial typing schemes based on the sequences of genes encoding surface antigens require databases that provide a uniform, curated, and widely accepted nomenclature of the variants identified. Due to the differences in typing schemes, imposed by the diversity of genes targeted, creating these databases has typically required the writing of one-off code to link the database to a web interface. Here we describe agdbNet, widely applicable web database software that facilitates simultaneous BLAST querying of multiple loci using either nucleotide or peptide sequences. 相似文献76.
CJ Cooksey 《Biotechnic & histochemistry》2017,92(2):134-140
The name, gentian, appeared about 1880. Immediately following its discovery in 1861, this violet dye was known as Violet de Paris or as methyl violet. Initially used as a textile dye, it was soon used to color virtually anything. The names and identity of the components, the varying modes of manufacture, analytical methods and the dye’s significant contribution to biological staining are discussed here. Finally, I discuss the dye’s declining medical use following the revelation of its toxic nature. 相似文献
77.
78.
Salah Azzi Theo CJ Sas Yves Koudou Yves Le Bouc Jean-Claude Souberbielle Patricia Dargent-Molina Irène Netchine Marie-Aline Charles 《Epigenetics》2014,9(3):338-345
The ZAC1 gene, mapped to the 6q24 region, is part of a network of co-regulated imprinted genes involved in the control of embryonic growth. Loss of methylation at the ZAC1 differentially methylated region (DMR) is associated with transient neonatal diabetes mellitus, a developmental disorder involving growth retardation and diabetes in the first weeks of post-natal life. We assessed whether the degree of methylation of the ZAC1 DMR in leukocytes DNA extracted from cord blood is associated with fetal, birth and post-natal anthropometric measures or with C-peptide concentrations in cord serum. We also searched for an influence of dietary intake and maternal parameters on ZAC1 DMR methylation. We found positive correlations between the ZAC1 DMR methylation index (MI) and estimated fetal weight (EFW) at 32 weeks of gestation, weight at birth and weight at one year of age (respectively, r = 0.15, 0.09, 0.14; P values = 0.01, 0.15, 0.03). However, there were no significant correlations between the ZAC1 DMR MI and cord blood C-peptide levels. Maternal intakes of alcohol and of vitamins B2 were positively correlated with ZAC1 DMR methylation (respectively, r = 0.2 and 0.14; P = 0.004 and 0.04). The influence of ZAC1 seems to start in the second half of pregnancy and continue at least until the first year of life. The maternal environment also appears to contribute to the regulation of DNA methylation. 相似文献
79.
80.
Joris?J?Glas Juan?M?Alba Sauro?Simoni Carlos?A?Villarroel Marije?Stoops Bernardus?CJ?Schimmel Robert?C?Schuurink Maurice?W?Sabelis Merijn?R?KantEmail author 《BMC biology》2014,12(1):98