Structural and RNAi characterization of the German cockroach lipophorin receptor, and the evolutionary relationships of lipoprotein receptors

This article is available from: http://www.biomedcentral.com/1471-2199/8/53[Background] Lipophorin receptors (LpRs) have been described in a number of insects, but functional studies have been reported only in locusts and mosquitoes. The aim of the present work was to characterize the LpR of the cockroach Blattella germanica, not only molecularly but also functionally using RNAi techniques, and to place LpRs in a phylogenetical context among lipoprotein receptors.[Results] We cloned a putative LpR from B. germanica (BgLpR) using RT-PCR methods. Two isoforms of BgLpR that differ from each other by an insertion/deletion of 24 amino acids were obtained from the fat body and the ovary. A phylogenetical analysis of lipoprotein receptors showed that BgLpR grouped with other sequences annotated as LpR in a cluster placed as a sister group of vertebrate low density lipoprotein receptors (LDLR) + lipoprotein receptor-related proteins 8 (LPR8) + vitellogenin receptors (VgR) + very low density lipoprotein receptors (VLDLR). The two BgLpR isoforms are expressed in different adult female tissues (fat body, ovary, brain, midgut, muscle) and in embryos. In ovaries and fat body, the two isoforms are similarly expressed during the first gonadotrophic cycle. mRNA levels in the fat body increase in parallel to vitellogenesis, whereas they decrease in the ovaries. BgLpR protein levels increase in parallel to vitellogenesis in both organs. Treatment with juvenile hormone increases BgLpR protein. RNAi experiments show that females with lower BgLpR expression have less lipophorin in the growing oocytes with respect to controls.[Conclusion] The two isoforms of BgLpR are structurally similar to other LpRs. Phylogenetical analyses show that LpRs and the group formed by vertebrate LDLR + LPR8 + VgR + VLDLR, diverged from a common ancestor and diversified in parallel. The different expression patterns in the fat body and the ovary, comparing mRNA and protein, indicate that the corresponding mechanisms regulating BgLpR expression are different. Experiments with JH III suggest that such a hormone regulates the expression of BgLpR posttranscriptionally. RNAi experiments indicate that BgLpR is a functional lipophorin receptor.Financial support from the Ministry of Education and Science, Spain (projects BOS2002-03359, BFU2005-00264, AGL2002-01169, AGL2005- 00773) and the Generalitat de Catalunya (2001 SGR 003245) is gratefully acknowledged. L.C. is recipient of pre-doctoral research grants (I3P) from CSIC. We thank Prof. Coby Schal (North Carolina State University) for generous gifts of anti-lipophorin antibody.Peer reviewe

Juvenile Hormone Titer Versus Juvenile Hormone Synthesis in Female Nymphs and Adults of the German Cockroach, Blattella germanica

Patterns of juvenile hormone have been intensively studied in the cockroach Blattella germanica under different physiological situations. However, data have been mainly obtained in vitro, and refer to hormone synthesized by isolated corpora allata, whereas information available on hormone concentration in the hemolymph is restricted to adult females. In order to complement our studies in vitro, we have measured juvenile hormone titer in the hemolymph of B. germanica females in four characteristic physiological situations: penultimate and last instar nymphs, adults during the first vitellogenic cycle, and adults transporting egg cases (ootheca). In general, a significant positive correlation between rates of hormone synthesis and concentration in the hemolymph is observed. The main disparities appear in the penultimate day of the period of ootheca transport, where titer is high whereas synthesis is low, and on day 6 of the first vitellogenic cycle, where synthesis increases whereas titer decreases. At these stages, the observed disparities between synthesis and titer might be explained by differential action of degradation enzymes

Concurrent hyperfractionated radiotherapy and chemotherapy for patients with limited small-cell lung cancer. Results from a single institution

BackgroundConcurrent use of chemotherapy and twice-a-day hyperfractionated radiotherapy is an efficacious scheme to control limited disease (LD) small-cell lung cancer (SCLC).AimOur main objective was to estimate initial results in overall survival for patients with LD-SCLC treated with concomitant chemotherapy and hyperfractionated thoracic radiotherapy in routine practice. Response to treatment and toxicity were also assessed.Material and MethodsForty-nine patients with confirmed LD-SCLC were treated at the Department of Radiotherapy of the Hospital General de Catalonia (Spain) from December 1999 to February 2007. The chemotherapy regimen was cisplatin (80 mg/m2) on day 1 and etoposide (100 mg/m2) on days 1, 2, and 3, every 21 day. The target dose to the tumor volume was 45 Gy. Prophylactic cranial irradiation (PCI), consisting of 30 Gy delivered in 15 fractions, was prescribed for all patients with a response rate >75% (23 of 30 patients).ResultsMedian follow-up was 12 months (range, 6–58 months) and median overall survival was 28.9 months. Two-year and 4-year survival rates were 56.4% and 30.1%, respectively. At 2 years, specific survival, local control, and systemic control were 64.2%, 88.8%, and 46.8%, respectively. Myelotoxicity and oesophagitis were the most severe toxicities.ConclusionsThe combined schedule – hyperfractionated irradiation plus concurrent chemotherapy – can be applied in routine practice in the context of early radiotherapy, which is considered standard treatment, with acceptable toxicity and similar results to those described in the literature

Hemimetabolous genomes reveal molecular basis of termite eusociality

Around 150 million years ago, eusocial termites evolved from within the cockroaches, 50 million years before eusocial Hymenoptera, such as bees and ants, appeared. Here, we report the 2-Gb genome of the German cockroach, Blattella germanica, and the 1.3-Gb genome of the drywood termite Cryptotermes secundus. We show evolutionary signatures of termite eusociality by comparing the genomes and transcriptomes of three termites and the cockroach against the background of 16 other eusocial and non-eusocial insects. Dramatic adaptive changes in genes underlying the production and perception of pheromones confirm the importance of chemical communication in the termites. These are accompanied by major changes in gene regulation and the molecular evolution of caste determination. Many of these results parallel molecular mechanisms of eusocial evolution in Hymenoptera. However, the specific solutions are remarkably different, thus revealing a striking case of convergence in one of the major evolutionary transitions in biological complexity

Oogenesis in the cockroach Blattella germanica. Fine tunning by miRNA

Conferencia invitada al V International Simposium of Developmental Biology celebrado en Ribeirão Preto (Brasil) entre el 18 y el 21 de noviembre de 2011.Peer Reviewe

The extracellular matrix protein SPARG is induced by juvenile hormone to regulate the dynamics of follicular cells during insect ovary maturation

Trabajo presentado en la 10th International Conference on Juvenile Hormones (JHX 2014), celebrada en Tsukuba (Japón) del 9 al 13 de junio de 2014.N

La maduración del oocito en insectos. ¿Cómo se regula la oogénesis en las distintas especies?

Trabajo presentado en el V Congreso de la Sociedad Española de Biología Evolutiva (SESBE 2016), celebrado en Murcia del 18 al 21 de enero de 2016.La formación y maduración del oocito es un proceso altamente controlado, ya que todos los acontecimientos deben ocurrir en el momento adecuado y en la secuencia correcta para que la posterior embriogénesis se realice correctamente. En insectos se distinguen dos modelos de ovario, los que tienen ovariolos de tipo panoístico y los que los tienen de tipo meroístico, más modificado. El ovario panoístico no sólo lo encontramos en insectos, sino que es el tipo más común en la mayoría de especies de invertebrados y vertebrados. Muchos de los genes que se expresan en ovarios y controlan procesos básicos, como la polaridad del oocito o la proliferación de las células germinales y de las células somáticas, están altamente conservados en las distintas especies de insectos, tanto si muestran el ovario panoístico como el meroístico, pero los mecanismos de regulación pueden ser diferentes en uno y otro. El estudio de estos mecanismos en una especie como Blattella germanica, con ovarios panoísticos, comparándolos con los de especies con ovarios meroísticos muy bien conocidas, como Drosophila melanogaster, nos permitirá reconstruir los cambios evolutivos que han pro piciado la transición de un modelo de ovario a otro.N

Modificación genética. Investigación para el control de Blatella germanica

Trabajo presentado en EXPOCIDA IBERIA 2020 (Congreso Profesional y Feria de Control de Plagas y Sanidad Ambiental), celebrado en Madrid el 20 y 21 de febrero de 2020.Utilización de herramientas moleculares para su posible uso en el control de plagas: el RNAi y el CRISPR-Cas9. Avances y estado actual de las investigaciones en CRISPR-Cas9 en el laboratorio y posibilidades futuras de uso en el control de cucarachas

Regulation of insect oogenesis. More than an endocrine interplay

Trabajo presentado en la 28th Conference of European Comparative Endocrinologists (CECE 2016), celebrado en Lovaina del 21 al 25 de agosto de 2016.Oogenesis is a crucial process in the animal kingdom to ensure the continuity of the species. Thus, it is not surprising that it is finely regulated. During the process of oogenesis, the ovarian follicle gets a series of signals that initiates competence, which will ultimately lead to maturation and oviposition. Insects are good models to study oogenesis as they have developed very different strategies to regulate it, and one of the most basic has been the design of different ovarian types. Two main types can be distinguished among insects: the panoistic and the meroistic. The panoistic is common in phylogenetically basal species, whereas the meroistic type predominates in distal insect groups. To study insect oogenesis we currently use the cockroach Blattella germanica as a model , a basal species with panoistic ovaries. The knowledge of this species can allow comparing its oogenesis with that of more mo dified species, like Drosophila melanogaster (with meroistic ovaries). In B. germanica , the juvenile hormone is the main reproductive hormone, involved in vitellogenesis control and oocyte maturation. We will review the role of juvenile hormone and its sig naling pathway, the function of ecdysone, which is necessary for chorion formation in adult cockroaches, and is also involved in the first steps of oogenesis, and the role of the Insulin pathway, which regulates tissue growth as well as vitellogenesis thro ugh the control of juvenile hormone synthesis. Finally, we will comment the involvement of these hormones in the signaling pathways (Hippo, Notch) that typically regulate insect oogenesis, in general.N