Accessory gland as a site for prothoracicotropic hormone controlled ecdysone synthesis in adult male insects

Insect steroid hormones (ecdysteroids) are important for female reproduction in many insect species and are required for the initiation and coordination of vital developmental processes. Ecdysteroids are also important for adult male physiology and behavior, but their exact function and site of synthesis remains unclear, although previous studies suggest that the reproductive system may be their source. We have examined expression profiles of the ecdysteroidogenic Halloween genes, during development and in adults of the flour beetle Tribolium castaneum. Genes required for the biosynthesis of ecdysone (E), the precursor of the molting hormone 20-hydroxyecdysone (20E), are expressed in the tubular accessory glands (TAGs) of adult males. In contrast, expression of the gene encoding the enzyme mediating 20E synthesis was detected in the ovaries of females. Further, Spookiest (Spot), an enzyme presumably required for endowing tissues with competence to produce ecdysteroids, is male specific and predominantly expressed in the TAGs. We also show that prothoracicotropic hormone (PTTH), a regulator of E synthesis during larval development, regulates ecdysteroid levels in the adult stage in Drosophila melanogaster and the gene for its receptor Torso seems to be expressed specifically in the accessory glands of males. The composite results suggest strongly that the accessory glands of adult male insects are the main source of E, but not 20E. The finding of a possible male-specific source of E raises the possibility that E and 20E have sex-specific roles analogous to the vertebrate sex steroids, where males produce primarily testosterone, the precursor of estradiol. Furthermore this study provides the first evidence that PTTH regulates ecdysteroid synthesis in the adult stage and could explain the original finding that some adult insects are a rich source of PTTH

Prospective individual patient data meta-analysis of two randomized trials on convalescent plasma for COVID-19 outpatients

Data on convalescent plasma (CP) treatment in COVID-19 outpatients are scarce. We aimed to assess whether CP administered during the first week of symptoms reduced the disease progression or risk of hospitalization of outpatients. Two multicenter, double-blind randomized trials (NCT04621123, NCT04589949) were merged with data pooling starting when = 50 years and symptomatic for <= 7days were included. The intervention consisted of 200-300mL of CP with a predefined minimum level of antibodies. Primary endpoints were a 5-point disease severity scale and a composite of hospitalization or death by 28 days. Amongst the 797 patients included, 390 received CP and 392 placebo; they had a median age of 58 years, 1 comorbidity, 5 days symptoms and 93% had negative IgG antibody-test. Seventy-four patients were hospitalized, 6 required mechanical ventilation and 3 died. The odds ratio (OR) of CP for improved disease severity scale was 0.936 (credible interval (CI) 0.667-1.311); OR for hospitalization or death was 0.919 (CI 0.592-1.416). CP effect on hospital admission or death was largest in patients with <= 5 days of symptoms (OR 0.658, 95%CI 0.394-1.085). CP did not decrease the time to full symptom resolution

Halloween gene expression during development and in adult <i>Tribolium</i>.

<p>The relative mRNA distribution of the Halloween genes during development and in adults was measured by qPCR. Expression was normalized to <i>rpS3</i> mRNA levels. The step in the ecdysteroid biosynthetic pathway catalyzed by each enzyme is shown on the right. Numbers on the x-axis indicate the day of each stage. E; embryo, F; females, O; ovaries, M; males, R; reproductive systems of males, 7dC; 7-dehydrocholesterol, 2,22,25-dE; 2,22,25-trideoxyecdysone (ketodiol), 2,22-dE; 2,22-dideoxyecdysone (ketotriol), 2-dE; 2-deoxyecdysone, 20E; 20-hydroxyecdysone. Note that the Black Box is believed to include multiple uncharacterized reactions converting 7dC to the ketodiol.</p

Knock down of <i>phm</i> and <i>spo</i> delays development and reduces ecdysteroid levels in <i>Tribolium</i>.

<p>Number of larvae that have undergone a molt after knock down of <i>phm</i> (<i>phm</i>-<i>RNAi</i>) and <i>spo</i> (<i>spo</i>-<i>RNAi</i>) expression 5 days (A) and 9 days (B) after injection with dsRNA. <i>GFP</i> dsRNA (<i>GFP-RNAi</i>) was used as a negative control. (C) Ecdysteroid levels in <i>spo-RNAi</i> and <i>phm-RNAi</i> larvae are reduced compared to the <i>GFP</i> control and to <i>spot-RNAi</i> 5 days after injection with dsRNA. Hemolymph ecdysteroid levels were below the limit of RIA detection (about 10 pg) in the hemolymph of <i>spo-RNAi</i> and <i>phm-RNAi</i> animals. L-L; larval-larval molt, L-P; larval-pupal molt.</p

Adult ecdysteroid levels are regulated by PTTH that may target the accessory glands in <i>Drosophila</i>.

<p>(A) <i>GFP</i> expression driven by a <i>torso-Gal4</i> line in the bi-nucleated secondary cells of a male accessory gland of <i>Drosophila</i>. Inserts are magnifications showing the two nuclei of spherical secondary cells. Green: GFP, Magenta: DAPI. (B-E) Gene expression was analyzed by qPCR in adult <i>Drosophila</i> males overexpressing <i>ptth</i> (<i>da>ptth</i>) and in animals with reduced expression of <i>torso</i> (<i>da>torso-RNAi</i>) or <i>ptth</i> (<i>da>ptth-RNAi</i>). <i>da>+</i> (<i>da></i> crossed to <i>w¹¹¹⁸,</i> genetic background used by VDRC for generating the RNAi lines) was used as a control and expression was normalized to <i>rpL23</i> mRNA levels. (B and C) Ecdysteroid levels estimated as levels of expression of ecdysteroid target genes <i>E74A, E74B</i> and <i>E75B</i>. (D and E) Expression of Halloween genes <i>phm, dib</i> and <i>sad</i>.</p

A model for sex-specific synthesis and action of ecdysteroids in adults.

<p>The ovaries of female <i>Tribolium</i> express <i>spo</i> and the genes for the terminal hydroxylases, including <i>shd</i>, required for synthesis of 20E. Male accessory glands also express a <i>spo</i>-like gene, <i>spot</i>, and the genes for the terminal hydroxylases required for synthesis of E, but not <i>shd</i>. However, s<i>hd</i> expression was detected in the carcass without the reproductive system indicating that E synthesized by the accessory gland might be converted to 20E in peripheral tissues, like during the larval stages. Alternatively, E produced by the accessory gland may be involved in male-specific hormone signaling or be transferred to females during mating. Multiple arrows indicate several steps in the biosynthetic pathway.</p

A large SARS-CoV-2 outbreak in a long-term care facility: lessons learned from a molecular epidemiological analysis

Trabajo presentado al 31st European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), celebrado online del 9 al 12 de julio de 2021.Peer reviewe