A Tunable Nd:CaYA104 Laser

The gain and tuning characteristics of the new laser material, neodymium-doped calcium-YALO (Nd: CaYA104), are obtained for crystals end-pumped by a 500 mW diode laser. The free-running laser output wavelength is about 1079 nm. The laser is continuously tunable from 1077.5 to 1084.5 nm with a Lyot filter in the cavity. Power output at the peak of the tuning curve is about 15 mW. With the addition of a thin, uncoated etalon the laser runs single-mode with an emission linewidth of 80 MHz. © 1992

Severe heat shock induces nucleolar accumulation of mRNAs in Trypanosoma cruzi

Several lines of evidence have shown that, besides its traditional function in ribosome biogenesis, the nucleolus is also involved in regulating other cellular processes such as mRNA metabolism, and that it also plays an important role as a sensor and coordinator of the stress response. We have recently shown that a subset of RNA Binding Proteins and the poly(A)+ RNA are accumulated into the Trypanosoma cruzi nucleolus after inducing transcription inhibition with Actinomycin D. In this study, we investigated the behaviour of the T. cruzi mRNA population in parasites subjected to severe heat shock, an environmental stress that also decreases the rate of RNA synthesis. We found that the bulk of poly(A)+ RNA is reversibly accumulated into the nucleolus when exposing T. cruzi epimastigote forms to severe heat shock. However, the Hsp70 mRNA was able to bypass such nucleolar accumulation. Together, these data reinforce the idea about the involvement of the T. cruzi nucleolus in mRNA metabolism during an environmental stress response. Interestingly, T. brucei procyclic forms did not induce nucleolar accumulation of poly(A)+ RNA under such stress condition, suggesting that different trypanosomatids have adopted different responses to deal with the same stress conditions.Fil: Nazer, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Verdún, Ramiro E.. University of Miami; Estados UnidosFil: Sanchez, Daniel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin

The <i>T. cruzi</i> mRNA population is partially accumulated into the nucleolus in response to severe heat shock.

<p>Localization of the mRNA population using either an (A) oligo(dT) or (B) mini-exon probe in untreated, heat-shocked and recovered <i>T. cruzi</i> epimastigotes. In addition, cells were pre-treated with RNase A before performing FISH (bottom panels). Nuclei were counterstained with DAPI (blue). The white arrows indicate the nucleolar localization for both probes. (C) RNA FISH using a Cy3-labelled oligo(dA)30 probe in untreated parasites and parasites exposed to 40°C for 2 h. N: nucleus, K: kinetoplast, Nu: nucleolus. Size bars represent 2 µm. Representative nuclei are shown. (D) A quantitative analysis of experiments is shown in panels (A) and (B). The results are expressed as mean +/− SD from at least three independent experiments (a minimum of 100 parasites per experiment were counted).</p

Hsp70 mRNA is able to bypass the nucleolar accumulation.

<p>FISH analysis for (A) α-Tub, (B) Smug and (C) Hsp70 mRNAs in parasites subjected to heat shock at 40°C for 2 h. In addition, cells were pre-treated with RNase A before performing FISH (bottom panels). The white arrows indicate the nucleolus. Nuclei were counterstained with DAPI (blue). Size bars represent 2 µm. Representative nuclei are shown. (D) A quantitative analysis of the experiments shown in panels (A), (B) and (C). The results are expressed as mean +/− SD from at least three independent experiments (a minimum of 100 parasites per experiment were counted).</p

Poly(A)+ RNA in response to heat shock is located in cytoplasmic granules but not into the nucleolus in <i>T. brucei</i>.

<p>Poly(A)+ RNA subcellular localization in <i>T. brucei</i> procyclic forms (A) untreated, (B) exposed to heat shock at 40°C for 2 h, (C) pre-treated with RNase A after heat shock, and (D) incubated with ActD for 4 h. The white arrows indicate the nucleolus. Nuclei were counterstained with DAPI (blue). N: nucleus, K: kinetoplast, Nu: nucleolus. Size bars represent 2 µm. Representative parasites are shown.</p