To be or not to be a piRNA: genomic origin and processing of piRNAs

Piwi-interacting RNAs (piRNAs) originate from genomic regions dubbed piRNA clusters. How cluster transcripts are selected for processing into piRNAs is not understood. We discuss evidence for the involvement of chromatin structure and maternally inherited piRNAs in determining their fate

A pontuszi tűzmoly [Duponchelia fovealis (Zeller)] tápnövényválasztásának viselkedési és elektrofiziológiai vizsgálata

A pontuszi tûzmoly (Duponchelia fovealis) hazai megjelenésével a növényházakban termesztett növények kártevôinek száma tovább gyarapodott. A faj soktápnövényû, tápnövénypreferenciája hiányosan ismert. Vizsgálataink elsôdleges célja a leginkább kedvelt növények és illatanyagaik megismerése, valamint ezen tudás birtokában kairomonnal csalétkezett rovarcsapdák kifejlesztése a kártevô monitorozására és esetleges tömegcsapdázására. Megfigyelésünkhöz az irodalmi adatok alapján a Cyclamen persicum, Euphorbia pulcherrima, Schlumbergera truncata, Chrysanthemum x grandiflorum és Ocimum basilicum növényeket választottuk, amelyeket tojásrakási viselkedés szempontjából teszteltünk, valamint összegyûjtött illatanyagaikkal mindkét nem imágóin elektroantennográfiás méréseket (EAG) végeztünk. A tojásrakási hely választásának és az elektroantennográfiás mérések eredménye alapján azt a következtetést vonhatjuk le, hogy a Chrysanthemum x grandiflorum bizonyult a legkedveltebb tápnövénynek

piRNA Biogenesis in Drosophila melanogaster

The PIWI-interacting RNA (piRNA) pathway is a conserved defense system that protects the genome integrity of the animal germline from deleterious transposable elements. Targets of silencing are recognized by small noncoding piRNAs that are processed from long precursor molecules. Although piRNAs and other classes of small noncoding RNAs, such as miRNAs and small interfering (si)RNAs, interact with members of the same family of Argonaute (Ago) proteins and their function in target repression is similar, the biogenesis of piRNAs differs from those of the other two small RNAs. Recently, many aspects of piRNA biogenesis have been revealed in Drosophila melanogaster. In this review, we elaborate on piRNA biogenesis in Drosophila somatic and germline cells. We focus on the mechanisms by which piRNA precursor transcription is regulated and highlight recent work that has advanced our understanding of piRNA precursor processing to mature piRNAs. We finish by discussing current models to the still unresolved question of how piRNA precursors are selected and channeled into the processing machinery

Small but sturdy: small RNAs in cellular memory and epigenetics

Cells in multicellular organisms have distinct identities characterized by their profiles of expressed genes. Cell identities can be stable over a long time and through multiple cellular divisions but are also responsive to extracellular signals. Since the DNA sequence is identical in all cells, a "cellular memory" of expression profiles is achieved by what are defined as epigenetic mechanisms. Two major molecular principles—networks of transcription factors and maintenance of cis-chromatin modifications—have been implicated in maintaining cellular memory. Here we describe recent studies demonstrating that short noncoding RNAs can also provide molecular signals that define epigenetic states of cells. Small RNAs can act independently or cooperate with chromatin modifications to achieve long-lasting effects necessary for cellular memory and transgenerational inheritance