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

Treiblmayr, Karl; Pascual, Núria; Piulachs, María‐Dolors; Keller, Thomas; Bellés, Xavier

doi:10.1673/031.006.4301

Cited by 62 publications

(58 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the MetKr-h1-E93 axis, or the MEKRE93 pathway (32), switches adult morphogenesis on and off, as observed, among other models, in B. germanica (29,32,39,40). Kr-h1 is expressed in juvenile instars, but its expression abruptly decreases at the beginning of N6 (29), coinciding with the gradual decrease of JH levels in the hemolymph (41). Treatment with JH reinduces Kr-h1 expression and inhibits adult morphogenesis, indicating that the decrease in Kr-h1 expression at the beginning of N6 is crucial for metamorphosis and that it is primarily triggered by the decrease of JH levels (29).…”

Section: An Mirna Family That Leads Metamorphosis To a Correct Conclumentioning

confidence: 85%

MiR-2 family regulates insect metamorphosis by controlling the juvenile hormone signaling pathway

Lozano

Montañez

Bellés

2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

101

View full text Add to dashboard Cite

In 2009 we reported that depletion of Dicer-1, the enzyme that catalyzes the final step of miRNA biosynthesis, prevents metamorphosis in Blattella germanica. However, the precise regulatory roles of miRNAs in the process have remained elusive. In the present work, we have observed that Dicer-1 depletion results in an increase of mRNA levels of Krüppel homolog 1 (Kr-h1), a juvenile hormone-dependent transcription factor that represses metamorphosis, and that depletion of Kr-h1 expression in Dicer-1 knockdown individuals rescues metamorphosis. We have also found that the 3′UTR of Kr-h1 mRNA contains a functional binding site for miR-2 family miRNAs (for miR-2, miR-13a, and miR-13b). These data suggest that metamorphosis impairment caused by Dicer-1 and miRNA depletion is due to a deregulation of Kr-h1 expression and that this deregulation is derived from a deficiency of miR-2 miRNAs. We corroborated this by treating the last nymphal instar of B. germanica with an miR-2 inhibitor, which impaired metamorphosis, and by treating Dicer-1-depleted individuals with an miR-2 mimic to allow nymphal-to-adult metamorphosis to proceed. Taken together, the data indicate that miR-2 miRNAs scavenge Kr-h1 transcripts when the transition from nymph to adult should be taking place, thus crucially contributing to the correct culmination of metamorphosis.insect metamorphosis | microRNA | juvenile hormone | evolution of metamorphosis | insect hormones M icroRNAs (miRNAs) are endogenous, ca. 22-nt, singlestrand, noncoding RNAs that regulate gene expression by acting posttranscriptionally through basepairing between the socalled seed sequence of the miRNA (nucleotides 2-8 at its 5′ end) and the complementary seed match sequence in the target mRNA (1). Since miRNAs were first discovered in the nematode Caenorhabditis elegans in the 1990s (2) and subsequently detected in other species (3), a remarkable diversity of them has been reported in a variety of organisms, including insects, plants, viruses, and vertebrates (4). Information available indicates that miRNAs are key players in gene regulatory networks, driving cell differentiation, conferring robustness, and channeling the development of multicellular organisms (5-8). Furthermore, the escalation in complexity in early bilaterian evolution has been correlated with a strong increase in the number of miRNAs (9-11). In insects, miRNAs have been shown to be involved in fine-tuning a number of biological processes such as cell proliferation, apoptosis and growth, oogenesis, and development, as well as response to biological stress (12).In 2009 we first looked at whether miRNAs might have a relevant role in the regulation of insect metamorphosis. Only a few published studies had considered the contribution of miRNAs to this process, but these focused on specific aspects, such as wing formation and neuromuscular development (13-16). They also used the fly Drosophila melanogaster as a model, a species that follows the holometabolan mode of metamorphosis, in which the juvenile stages are extre...

show abstract

Section: An Mirna Family That Leads Metamorphosis To a Correct Conclumentioning

confidence: 85%

MiR-2 family regulates insect metamorphosis by controlling the juvenile hormone signaling pathway

Lozano

Montañez

Bellés

2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

101

View full text Add to dashboard Cite

show abstract

“…Reproduction in B. germanica females is under the control of JH, which paces the reproductive rate and governs the duration of the preoviposition period, and whose absence enables a protracted gestation (for reviews, see Schal et al, 1997;Treiblmayr et al, 2006). The rate of oocyte maturation in socially isolated, group-housed and over-crowded females reflects the rates of JH production by the respective CA; smaller basal oocytes in isolated and crowded females (20 females per dish) corresponded well with lower rates of JH synthesis, whereas larger oocytes in pair-housed and grouped females (eight per dish) paralleled higher rates of JH synthesis on day 6.…”

Section: Discussionmentioning

confidence: 99%

“…We therefore hypothesized that the female's reproductive physiology would be unresponsive to social interactions during gestation. Nevertheless, because JH biosynthesis is known to increase slightly before egg hatch, and the basal oocytes grow slightly as well (Gadot et al, 1989b;Schal et al, 1997;Treiblmayr et al, 2006), we hypothesized that social interactions in the late phase of gestation might influence the second ovarian cycle.…”

Section: Responses To Social Interactions During Gestationmentioning

confidence: 99%

“…However, unlike oviparous species, the egg case is then rotated 90° and retained externally by the female, attached at the vestibulum (an outer chamber that lies above the enlarged seventh abdominal sternite), until the nymphs hatch approximately 21-22days later at 27°C (Roth and Stay, 1962). This incubation period is functionally similar to gestation in ovoviviparous cockroaches, as the corpora allata (CA) are inhibited in both groups, suppressing juvenile hormone III (JH) production (Tobe and Stay, 1985;Gadot et al, 1989a;Gadot et al, 1989b;Gadot et al, 1991) (for reviews, see Schal et al, 1997;Treiblmayr et al, 2006). As the major gonadotropic hormone, JH is produced and released by the CA in a stage-specific manner and it paces the female's reproductive rate.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, during gestation, JH production remains low, but at the end of gestation, before egg hatch, JH titers slightly increase and the basal oocytes grow slightly as well (Gadot et al, 1989a;Gadot et al, 1989b). The average length of the basal oocytes is a reliable measure of the reproductive stage because all basal oocytes mature synchronously and their length correlates well with both the activity of the CA (as measured by their JH biosynthesis in vitro) and with JH titer in the hemolymph (as measured by GC-MS) (Sevala et al, 1999;Treiblmayr et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Differential physiological responses of the German cockroach to social interactions during the ovarian cycle

Uzsák

Schal

2012

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYIn many animal species, social interactions can influence the morphology, physiology and behavior of individuals, including their rate of development and reproduction. Reproduction in cockroaches is regulated by juvenile hormone III (JH), and social interactions have been shown to accelerate female reproduction in the German cockroach, Blattella germanica (L.), by stimulating JH production. However, it is not clear in this or any other insect species whether social facilitation of the reproductive rate occurs throughout the ovarian cycle or only at certain stages. We compared the effects of social interactions during the preoviposition period (when JH production is high) and during gestation (when little JH is produced), as well as during the first ovarian cycle (when females are virgin) and the second ovarian cycle (after females had mated). Social interaction with one conspecific female was sufficient to accelerate JH production and oocyte maturation, but this effect was reversed by crowding. Social interactions also accelerated the onset of sexual receptivity in virgin females. However, social interactions failed to shorten gestation, suggesting that social cues stimulate JH production only when the corpora allata (CA) are active and not when CA activity is suppressed by the central nervous system. Females were most responsive to transient social isolation and transient social interactions when 2-3days old, suggesting that they are particularly sensitive to social interactions when their CA become active. Overall, these results show that all JH-dependent events in the reproductive cycle of B. germanica females are under the strong influence of social interactions.

show abstract

Origin and Evolution of Insect Metamorphosis

Bellés

2011

Encyclopedia of Life Sciences

Self Cite

View full text Add to dashboard Cite

Brazilian livestock stands out in the international scenario representing the largest cattle herd in the world. In this context, the costs of livestock activities are high, especially the investment in animal health products, such as antiparasites, in order to control the damages associated with the deleterious effects of the parasites, with greater relevance for tick infestations and Haematobia irritans, known as fly of the horns. Currently, the traditional control of this parasite uses indiscriminate conventional pesticides with broad spectrum, exposing animals, living beings and the environment to toxic risks, accelerating the resistance process. However, Piriproxifem belonging to the class of insect growth inhibitors (IGR), is a biorational parasiticide, with selective action mechanism for insects, being highly safe for the control of the immature forms of H.irritans. The oral efficacy of Piriproxifem allows the development of an oral dosage form, appropriating the pharmaceutical technology to corroborate strategies for the control of the asset release system, such as the use of polymer matrices impregnated, in order to increase the residence time of the drug in rumem, and consequently prolong the time of action of the insect control. The main purpose of the controlled release system is to increase the safety of the product and to extend the pharmacological action when associated to the polymers PEG, PCL e PLGA, promoting the gradual dissolution of the drug. The formulation was physicochemically characterized by infra-red spectroscopy (FTIR), morphological assays by scanning electron microscopy (SEM) and thermal analysis by thermogravimetric (TGA) assays. The methodologies used for the development of the release system and the in vitro dissolution profile were evaluated. The results demonstrated that it was possible to develop a controlled release formulation containing pyriproxyfen by the evaluation of the dissolution kinetic study, and the incorporation methodologies did not differ significantly in the release profile. The spectral analyzes elucidated the structures and their characteristic attributions of each polymer. The highest volumetric fraction found in the micrographs of the PCL, PLGA and PEG polymers was 96.02%, 76.24% and 86.88% represented by the dipped incorporation method, whereas the lowest volumetric fraction was 94, 85%, 75.84% and 84.84% corresponding to the impregnated method. TGA and DTG demonstrated the results of initial mass loss (6.9 ± 0.02), and it was possible to evaluate the degradation temperature of each formulation.

show abstract

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

Cited by 62 publications

References 22 publications

MiR-2 family regulates insect metamorphosis by controlling the juvenile hormone signaling pathway

MiR-2 family regulates insect metamorphosis by controlling the juvenile hormone signaling pathway

Differential physiological responses of the German cockroach to social interactions during the ovarian cycle

Origin and Evolution of Insect Metamorphosis

Contact Info

Product

Resources

About