Novi propisi iz područja zaštite zdravlja, sigurnosti na radu i zaštite od požara - 12/17. - 2/18.

<div><p><i>couch potato</i> (<i>cpo</i>) encodes an RNA binding protein that has been reported to be expressed in the peripheral and central nervous system of embryos, larvae and adults, including the major endocrine organ, the ring gland. A polymorphism in the <i>D</i>. <i>melanogaster cpo</i> gene coding region displays a latitudinal cline in frequency in North American populations, but as <i>cpo</i> lies within the inversion <i>In(3R)Payne</i>, which is at high frequencies and itself shows a strong cline on this continent, interpretation of the <i>cpo</i> cline is not straightforward. A second downstream SNP in strong linkage disequilibrium with the first has been claimed to be primarily responsible for the latitudinal cline in diapause incidence in USA populations.Here, we investigate the frequencies of these two <i>cpo</i> SNPs in populations of <i>Drosophila</i> throughout continental Europe. The advantage of studying <i>cpo</i> variation in Europe is the very low frequency of <i>In(3R)Payne</i>, which we reveal here, does not appear to be clinally distributed. We observe a very different geographical scenario for <i>cpo</i> variation from the one in North America, suggesting that the downstream SNP does not play a role in diapause. In an attempt to verify whether the SNPs influence diapause we subsequently generated lines with different combinations of the two <i>cpo</i> SNPs on known <i>timeless</i> (<i>tim)</i> genetic backgrounds, because polymorphism in the clock gene <i>tim</i> plays a significant role in diapause inducibility. Our results reveal that the downstream <i>cpo</i> SNP does not seem to play any role in diapause induction in European populations in contrast to the upstream coding <i>cpo</i> SNP. Consequently, all future diapause studies on strains of <i>D</i>. <i>melanogaster</i> should initially determine their <i>tim</i> and <i>cpo</i> status.</p></div

Electromagnetic field effects in Drosophila melanogaster

Many higher animals have evolved the ability to use the Earth’s magnetic field, particularly for orientation. However, the biophysical mechanism by which magnetoreception is achieved remains elusive. One theoretical model (the radical pair mechanism - RPM) proposes that the geomagnetic field is perceived by chemical reactions involving the blue-light photoreceptor Cryptochrome (CRY). Recent evidence supports the RPM in Drosophila melanogaster and reveals a mechanistic link with the circadian clock. Here I have confirmed, albeit with rather different results, that a low frequency electromagnetic field (AC-EMF) along with a Static Field (SF) exposure does affect circadian and activity behaviour in the fruit fly. Furthermore, I have developed two new assays to investigate the effects of EMF in Drosophila melanogaster, negative geotaxis and an additional light wavelength preference assay, revealing a net CRY-dependent response. My data support the idea of CRY mediated magnetoreception, thereby indirectly supporting the RPM. Furthermore, I provide some striking new results that challenge our view that only the canonical clock neurons contribute to behavioural rhythms in Drosophila melanogaster

Nucleotide alignment of the <i>cpo</i> region in <i>D</i>. <i>melanogaster</i> and <i>D</i>. <i>simulans</i>.

<p><i>D</i>. <i>melanogaster</i> sequences, top two rows. The box indicates the position of SNP <i>cpo</i>^{<i>48034(A/T)</i>} which appears to be monomorphic in <i>D</i>. <i>simulans</i>. The arrow points to a position which is polymorphic in <i>D</i>. <i>simulans</i> but not in <i>D</i>. <i>melanogaster</i>.</p

Diapause incidence in the Treviso population (TOT) and in the four sublines (<i>sTA</i>, <i>sTT</i>, <i>sCA</i> and <i>sCT</i>).

<p>Y axis: percentage diapause averaged among 5/6 replicates (±SEM). A) Diapause in LD 8:16 at 12 and 28 days (dotted and plain bars respectively). B) Diapause in LD 16:8. Gray bars: Treviso population. For a description of the genotypes of the populations see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0162370#pone.0162370.t002" target="_blank">Table 2</a>.</p

<i>cpo</i> and <i>5’</i> sequences used for neutrality tests.

<p>A: details regarding the two genomic regions amplified, sequenced and analysed. Their length is reported in base pairs. N: number of individuals sequenced. Details of the four populations analysed. Latitude in degrees North. N: number of sequences analysed for the <i>5</i>’ and polymorphic <i>cpo</i> region (referred to as <i>5’</i> and <i>cpo</i> respectively). B: indel polymorphisms in the <i>cpo</i> and 5’ regions. Values calculated with DNAsp v5.10.01, using multiallelic model (all alleles are considered, also the ones which overlap in sequence). Mean indel length event is calculated averaging the length of every indel event in the alignment. Mean indel is calculated considering every indel event in each sequence. Values are in nucleotides. C. Results of the Tajima’s and Fu and Li’s test statistic. Results including and not including indels presented.* p<0.05, ** p<0.01. D. Results of the HKA test. Total number of sites in base pairs, gaps excluded S OBS: observed number of segregating sites (intraspecies comparison). S EXP: expected number of segregating sites (intraspecies comparison). DIFF OBS: observed number of differences (interspecies comparison). DIFF EXP: expected number of differences (interspecies comparison).</p

<i>tim</i> and <i>cpo</i> genotypes of the four lines created from a population from Treviso, Italy.

<p>The diapause incidence of these lines was then assessed at two different photoperiods (LD 8:16 and LD 16:8) and at two time points: after 12 and 28 days.</p

European frequencies of <i>cpo</i> polymorphisms and <i>In(3R)Payne</i>.

<p>Frequency of <i>cpo</i>^{<i>347Val</i>} in European populations plotted against latitude. Open circles, southern- and northern-most American populations [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0162370#pone.0162370.ref005" target="_blank">5</a>], filled circles, European populations. * p<0.05. B) Frequency of <i>cpo</i>^{<i>48034A</i>} in European populations against latitude. C) Frequency of In(3R)Payne against latitude.</p

Geographical analysis of diapause inducibility in European Drosophila melanogaster populations.

Seasonal overwintering in insects represents an adaptation to stressful environments and in European Drosophila melanogaster females, low temperatures and short photoperiods can induce an ovarian diapause. Diapause may represent a recent (<15Ky) adaptation to the colonisation of temperate Europe by D. melanogaster from tropical sub-Saharan Africa, because African D. melanogaster and the sibling species D. simulans, have been reported to fail to undergo diapause. Over the past few centuries, D. melanogaster have also invaded North America and Australia, and eastern populations on both continents show a predictable latitudinal cline in diapause induction. In Europe however, a new diapause-enhancing timeless allele, ls-tim, is observed at high levels in southern Italy (∼80%), where it appears to have arisen and has spread throughout the continent with a frequency of ∼20% in Scandinavia. Given the phenotype of ls-tim and its geographical distribution, we might predict that it would work against any latitudinal cline in diapause induction within Europe. Indeed we reveal that any latitudinal cline for diapause in Europe is very weak, as predicted by ls-tim frequencies. In contrast, we determine ls-tim frequencies in North America and observe that they would be expected to strengthen the latitudinal pattern of diapause. Our results reveal how a newly arisen mutation, can, via the stochastic nature of where it initially arose, blur an otherwise adaptive geographical pattern

TLR4 and TLR2 activation.

<p>Triggering of TLR4 and TLR2 in transfected HEK293 cells. HEK293/TLR4/p-Nifty2-SEAP and HEK293/TLR2/p-Nifty2-SEAP cells were either untreated (none) or treated with BpWT or BpCyaA− for 16 h. Positive control (PC) for TLR4 stimulation was <i>E. coli</i> LPS (0.1 µg/ml) and positive control for TLR2 stimulation was Pam2CSK4 (0.1 µg/ml). SEAP activity in supernatants of cell cultures was measured. Data are reported as fold increase of SEAP activity over untreated values. Mean expression ± SE of ten independent experiments is indicated. * <i>p</i><0.05 <i>vs</i> none; ° <i>p</i><0.05 <i>vs</i> PC.</p

Analysis of MyD88-independent pathway induction.

<p>MDDC were either untreated (none) or treated with BpWT or BpCyaA−. Phosphorylation of IRF3 was determined at the indicated time-points by Western blot. Data are from one representative out of three independent experiments performed with MDDC obtained from different donors.</p