Male Sexual Maturation Research Articles

Methoprene treatment and its effect on male reproductive organ size and female remating in a fruit fly.

Methoprene, a juvenile hormone analog, is used to accelerate sexual maturation in males of species of economic importance in support to the sterile insect technique (SIT). In the SIT, mass-reared sterile males are released into the field and need to survive until they reach sexual maturation, find a wild female, mate with her and then induce female sexual refractoriness, so she will not remate with a wild counterpart. The use of methoprene shortens the time between release and copulation. However, in South American fruit flies, Anastrepha fraterculus, the ability of methoprene-treated males to inhibit female remating has been shown to be lower than wild males, when methoprene was applied by pupal immersion or topical application. Here we evaluated the possibility of incorporating methoprene into the male diet at different doses and the ability of those males to inhibit female remating, as well as the effect of methoprene on male reproductive organ size, due to the possible correlation between male accessory gland size and their content, and the role of male accessory gland proteins in female inhibition. We found that A. fraterculus males fed with methoprene in the adult protein diet at doses as high as 1% were less likely to inhibit female remating, however, at all other lower doses males had the same ability as untreated males to inhibit female remating. Males fed with methoprene had bigger male accessory glands and testes compared to methoprene-deprived males. We demonstrate that the incorporation of methoprene in adult male diets is possible in this species and potentially useful as a post-teneral, pre-release supplement at doses as low as 0.01%. Even at higher doses, the percentage of females remating after 48 h from the first copulation is sufficiently low in this species so as not compromise the efficiency of the SIT.

Penile diameter during puberty in boys: aretrospective analysis of longitudinally obtained data.

Tanner staging is the standard for rating sexual maturation (SMR) in boys (pubic hair (PH) and genital (G)development). G staging is tripartite innature and is prone to ambiguity because it is based upon somewhat vague visual cues that may lead to erroneous assessments and medical errors. Measurement of penile growth (penile girth or diameter) may provide an additional tool (in addition to the orchidometer) to make Gstaging more valid. Although studies on penile growth (either circumference of width) have been reported, none were longitudinal. Therefore, our objective was to compare penile development in boys- measured as penile diameter (PD)- to PH stage and testicular volume (TV) and secondarily to G stage; moreover, to do so on a longitudinal basis. Charts of 61 boys, ages 6-21years of age, who were seen longitudinally, were reviewed. Each boy had his PD and TV measured along with his PH and G stage assessed on a quarterly to semi-annual basis. PD increased significantly among PH stages II, III, and IV only. PD increased significantly among G stages I, II, III and IV only. PD correlated well with TV. There were significant correlations between PD and TV in all PHstages. However, for G stage correlations were not significant for stages II, III, and IV. PH stage was a better predictor of PD than G stage. Measuring PD may be another tool to help in objectifying male SMR during puberty and overcome the vagueness encountered with the visual SMR G stage scales.

Surrounding gas composition affects the calling song development in the two-spotted cricket (Gryllus bimaculatus).

Male crickets emit acoustic signals (i.e., songs) by chirping using their forewings. Although the mechanisms and adaptive functions of these songs are well studied, knowledge about how songs develop within a generation is relatively scarce. Our previous work demonstrated a stable peak frequency at 5.7 kHz in the calling songs recorded from mature adult male crickets (Gryllus bimaculatus). In the present study, we monitored changes in the frequency component over time from the sexual maturity stage (early adult stage). We recorded 300 calling songs from a pool of 122 adults. The peak frequency distribution was lower and unstable (i.e., greater coefficient of variance) in the early adult stage. The mean peak frequency was 4.9 kHz on day 3, but gradually converged to 5.8 kHz over the 2-week adult stage. Immature adult males (emitting immature songs) produced an appropriately tuned song with a peak frequency of 5.8 kHz in an environment of 80% helium and 20% oxygen. These results suggest that the frequency component of the calling song is acquired during the early to mid-adult stage, and may be related to sexual maturation in males. Findings from the helium substitution experiment revealed that physical resistance from surrounding gas molecules negatively affect the stability of male singing, and that muscle development and forewing hardening may contribute to the maturation of singing, suggesting that females may adaptively select sexually mature males based on song traits.

Predictors of testosterone in zoo-managed male African elephants (Loxodonta Africana).

Reproductive complications for both male and female zoo-managed African elephants (Loxodonta africana) contribute to the rapidly declining population. In zoo-managed bull elephants, few studies have explored the potential physiological, physical, social, and environmental factors that influence bull fertility, particularly, androgen production. Testosterone is the essential steroid hormone for male sexual maturation and inadequate concentrations can be detrimental for spermatogenesis. Testosterone, fecal glucocorticoid metabolites, leptin, glucose, insulin, and triglycerides were analyzed from weekly fecal and blood serum samples taken over 6 months from six zoo-managed African elephant bulls (10-19 years of age). Testosterone levels were compared to endocrine factors, weekly social and environmental variables, daily musth signs, and body condition scores (BCS). The glucose-to-insulin ratio (G:I) was the only physiological biomarker found to be positively associated with testosterone. Predictive physical variables included Musth Score (+) and Moderate Exercise (+). Bulls with BCSsignifying overweight (BCS 4) had lower testosterone (36.6 ± 1.6 ng/g fecal extraction [FE]) than bulls with healthyBCS 3; 51.2 ± 4.9 ng/g FE). Numerous social variables influenced testosterone concentrations, including Total Contact Day (+), Female Interaction Day (+), Indirect Contact Day (+), Indirect Contact Night (+) and Total No Contact (-). Both percentage of Time Outdoor and Time Mixed positively influenced testosterone, whereas testosterone decreased for percentage of Time Indoors. Each additional daily browse opportunity increased testosterone by approximately 7 ng/g FE. In managed care, the emphasis should be placed on optimizing these predictors of testosterone production to promote bull reproductive health.

Effect of Wolbachia Infection and Adult Food on the Sexual Signaling of Males of the Mediterranean Fruit Fly Ceratitis capitata.

Simple SummaryThe Mediterranean fruit fly (medfly) can infest many plant species and survive in different climatic conditions, thus leading to its invasion in new geographical regions and causing great economic losses in fruit production. Insecticides have been the major approach for the suppression of medfly populations for decades. However, concerns regarding insecticide impact on the environment led to the development of environmentally friendly techniques that rely on field releases of sterile males that produce no viable offspring when mated with wild females. One method of male sterilization is their infection with bacteria such as Wolbachia that induce sterility in infected males when crossed with uninfected wild females. The released sterile males should be competitive with wild males for mating with wild females. Therefore, it is important to evaluate the effect of Wolbachia on traits that determine male mating success, such as sexual pheromone signaling, and assess potential ways to improve mating success (i.e., enrichment of male diet with protein). In this study, we demonstrate that Wolbachia infection decreases sexual signaling frequency, but protein-enriched diets cannot counteract this negative effect. Our results contribute to the assessment of Wolbachia infection as an additional tool for population suppression of insect pests.Sexual signaling is a fundamental component of sexual behavior of Ceratitis capitata that highly determines males’ mating success. Nutritional status and age are dominant factors known to affect males’ signaling performance and define the female decision to accept a male as a sexual partner. Wolbachia pipientis, a widespread endosymbiotic bacterium of insects and other arthropods, exerts several biological effects on its hosts. However, the effects of Wolbachia infection on the sexual behavior of medfly and the interaction between Wolbachia infection and adult food remain unexplored. This study was conducted to determine the effects of Wolbachia on sexual signaling of protein-fed and protein-deprived males. Our findings demonstrate that: (a) Wolbachia infection reduced male sexual signaling rates in both food regimes; (b) the negative effect of Wolbachia infection was more pronounced on protein-fed than protein-deprived males, and it was higher at younger ages, indicating that the bacterium regulates male sexual maturity; (c) Wolbachia infection alters the daily pattern of sexual signaling; and (d) protein deprivation bears significant descent on sexual signaling frequency of the uninfected males, whereas no difference was observed for the Wolbachia-infected males. The impact of our findings on the implementation of Incompatible Insect Technique (IIT) or the combined SIT/IIT towards controlling insect pests is discussed.

Microbial community characteristics of the intestine and gills of medium-form populations of Sthenoteuthis oualaniensis in the South China Sea

Sthenoteuthis oualaniensis (purpleback squid) is an excellent biological resource in the South China Sea. However, the microbiological characteristics of this South China Sea squid, especially those of the medium-form of different sexes and gonadal maturities, are poorly understood. In this study, the characteristics of the bacterial community in the intestinal and gill tissues of female and male S. oualaniensis with different gonadal maturities, collected from the Nansha Sea of China in spring 2020, were analyzed. The results showed that Tenericutes, Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla in the intestinal microbial samples of female immature gonad (FN), male immature gonad (MN), and male sexual maturity (MY) samples of the S. oualaniensis populations. Proteobacteria, Firmicutes, Bacteroidetes, and Tenericutes were the dominant phyla in the intestinal microbial sample of the female sexual maturity (FY) group. The microbial community in the gills differed from that of the intestinal flora. The dominant phyla in the gill samples were Proteobacteria, Firmicutes, and Bacteroidetes, regardless of sex or gonadal maturity. According to the random forest analysis, the gill samples had significantly (p<0.001) more Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in the top 20 than the intestinal samples. Correlation analysis showed that the mantle length of S. oualaniensis was significantly (p<0.05) negatively correlated with the abundance of Tenericutes, but significantly (p<0.01) positively correlated with Firmicutes and Bacteroidetes. The mantle length of FY was significantly (p<0.05) longer than that of the other types. The results indicated that the differences in the intestinal bacterial community were related to the growth and feeding characteristics of S. oualaniensis of different sexes and maturities.

Development of male-larger sexual size dimorphism in a lizard: IGF1 peak long after sexual maturity overlaps with pronounced growth in males.

Squamate reptiles have been considered to be indeterminate growers for a long time. However, recent studies demonstrate that bone prolongation is stopped in many lizards by the closure of bone growth plates. This shift in the paradigm of lizard growth has important consequences for questions concerning the proximate causes of sexual size dimorphism. The traditional model of highly plastic and indeterminate growth would correspond more to a long-term action of a sex-specific growth regulator. On the other hand, determinate growth would be more consistent with a regulator acting in a sex-specific manner on the activity of bone growth plates operating during the phase when a dimorphism in size develops. We followed the growth of males and females of the male-larger Madagascar ground gecko (Paroedura picta) and monitored the activity of bone growth plates, gonad size, levels of steroids, expression of their receptors (AR, ESR1), and expression of genes from the insulin-like growth factor network (IGF1, IGF2, IGF1R, and IGF2R) in livers. Specifically, we measured gene expression before the onset of dimorphic growth, at the time when males have more active bone growth plates and sexual size dimorphism was clearly visible, and after a period of pronounced growth in both sexes. We found a significant spike in the expression of IGF1 in males around the time when dimorphism develops. This overexpression in males comes long after an increase in circulating testosterone levels and sexual maturation in males, and it might be suppressed by ovarian hormones in females. The results suggest that sexual size dimorphism in male-larger lizards can be caused by a positive effect of high levels of IGF1 on bone growth. The peak in IGF1 resembles the situation during the pubertal growth spurt in humans, but in lizards, it seems to be sex-specific and disconnected from sexual maturation.

Body growth, mass at sexual maturity, and sexual dimorphism in Florida panthers (Puma concolor coryi)

Abstract Recognizing individual variation in body growth characteristics and size at sexual maturity is of particular interest because they indicate a potential source of variance in survival and reproductive fitness. I used the Richards group of unified models method to examine body growth characteristics, mass at sexual maturity, and development of sexual size dimorphism in Florida panthers (Puma concolor coryi). A larger asymptotic body size and mass at sexual maturity in males resulted from a greater instantaneous growth rate across the life span and longer duration of growth than in females. Juvenile males attained larger body mass than female counterparts before achieving independence and sexual maturity, suggesting that a greater instantaneous growth rate developed from precopulatory intrasexual selection. Body mass growth rapidly decreased proximate to the minimum age at first conception in both sexes, suggesting that energetic costs of reproduction inhibited additional growth. Intrasexual selection among males to enhance fighting ability and promote access to a territory and mates is implicated as the cause for sexual size dimorphism, together with more direct underlying energetic costs of reproduction in females. The results provide uniform sex-specific body mass-at-age growth and mass at sexual maturity statistics for comparison with other puma populations and reference values to implement measurable criteria to evaluate trends in Florida panther population health.

Some histological reveals on reproduction of one of the lessepsian species, Nemipterus randalli in Antalya (Turkey)

In this study, the reproduction of Nemipterus randalli, one of the lessepsian fish catch from the Gulf of Antalya, Turkey was interpreted histologically. Regarding the fish used in this study (N = 1715), it is noteworthy to mention that male individuals are larger than females. The first sexual maturity in males was determined 17 cm TL and 60 g in BW, whereas 13 cm TL and 25 g BW in females. Females reached sexual maturity at age I+ and males at the age of II+. Seven different stages (O1-O7) were identified in oocyte maturation in the ovaries. The spawning time of N. randalli in the Gulf of Antalya extended from June to October (Peak on July- August), given the histological interpretation of the development in gonads and the GSI % data. According to this data, N. randalli may be described to have a Batch spawner characteristic.

A Preliminary Study of the Morphological and Ecological Characteristics of Plestiodon japonicus (Scincidae, Squamata) on the Danjo Islands, Western Japan

The morphological and ecological characteristics are studied for the population of Plestiodon japonicus of the Danjo Islands, a group of small islands in the East China Sea, on the basis of field observations and data from museum specimens. The population density of the lizards in this island group was estimated to be higher than those in conspecific mainland populations. Also, P. japonicus of the Danjo islands were differentiated from the latter by the following combination of characters: larger number of mid-body scale rows and subdigital scales, blackish juvenile coloration with different stripe pattern, faded tail color, and delayed sexual maturity in males. The evolutionary implications of these findings are briefly discussed.

Precocious puberty in male wild boars: a possible explanation for the dramatic population increase in Germany and Europe.

BackgroundThe wild boar population in Europe is steadily growing, one of the reasons for this increase probably being the high reproductive potential of this large mammal. Population management is important to stabilise wild boar numbers and a great deal of attention is focusing on the reasons, which might contribute to the high reproductive rates. Understanding the timing of puberty attainment provides information required for proper management practices. Knowledge of the earliest expected time of sexual maturation in male wild boars is limited, research being mostly focused on females. Previous hunting references indicate that sexual maturity in males occurs in the second year after birth. In contrast, male domestic pigs become sexually mature from about seven months of age. Thus, aims of this study were to investigate (1) whether there is a physiological ability for reproduction also in male wild boars of a younger age and (2) whether the body weight of wild boar males has a more important role than age in driving the maturation of the testis.MethodsMale wild boar individuals were sampled during hunting drives in the eastern part of Lower Saxony in Germany. Testes with epididymides from 74 males were collected and prepared for histological examination and immunohistochemistry. The reproductive status could be ascertained based on development/occurrence of different germ cell populations using histology and based on the immunohistochemical detection of the anti-Müllerian hormone and androgen receptor.ResultsIn this study, male wild boars aged nine to ten months already passed puberty and were able to reproduce if they had reached the appropriate body condition of about 29 kg dressed weight. Immunopositivity to the anti-Müllerian hormone in Sertoli cells was evident only in prepubertal animals and decreased with the onset of puberty. No immunoreaction was evident at postpuberty. The androgen receptor was detected in Sertoli cells, peritubular cells and Leydig cells, surprisingly already in Sertoli cells of prepubertal wild boars as well depending on body weight. Moreover, two-thirds of young males aged about ten months were precociously reproductively mature, showing histologically the presence of spermatozoa in testes and epididymides.ConclusionsAs piglets are mostly born in spring, also these young male individuals could target the heat of female wild boars in the winter months, resulting in the observed population increase. Therefore, a reduction in wild boar numbers should also focus on piglets of both sexes.

Learning From Instructional Videos: Learner Gender Does Matter; Speaker Gender Does Not.

One crucial design characteristic of auditory texts embedded in instructional videos is the speaker gender, which has received some attention from empirical researcher in the recent years. Contrary to the theoretical assumption that similarity between the speaker’s and the learner’s gender might positively affect learning outcomes, the findings have often been mixed, showing null to contrary effects. Notwithstanding the effect on the outcomes, a closer look at how the speaker’s gender and speaker–learner similarities further determine cognitive variables, such as different cognitive load types, is overdue. Moreover, on the part of the learner, the role of situational interest in the learning topic that might be gender related has been neglected so far. Therefore, this study explored the role of speaker and learner gender and their interaction regarding learning outcomes. We broaden our perspective by investigating the effects of gender-related differences concerning situational interest in the topic being taught and by determining different types of cognitive load. In a 2 (female/male speaker) × 2 (female/male learner) within- and between-subject design, 95 students learned about female and male human sexual maturity with an instructional video containing auditory explanations. Analysis results indicate that speaker gender and speaker–learner gender similarity had no impact on learning gains, situational interest, and cognitive load types. However, the results demonstrate that learner’s gender, especially for the topic of female sexual maturity, matters the most in line with the assessed variables. Compared with males, females had higher learning gains, reported higher interest in the topic, and invested more germane cognitive resources. Thus, instructional designers may want to consider learner gender-dependent interest and how it can be triggered when creating videos with auditory explanations.

Scales of our lives: Sex identification of Temminck’s pangolin (Smutsia temminckii) using scales retrieved out of the illegal wildlife trade

Pangolins are the most trafficked wild mammals, with their scales in high demand. Scales are often the only part of the animal confiscated from the trade, but they represent accessible material for forensic investigations, including for sexing. This study aimed to develop a sexing tool for Temminck’s pangolin, using scales for hormone quantification. Scales from males and females were liquidised using keratinase and the resulting suspension analysed for progestagen and androgen metabolite (scPM and scAM) concentrations. Scale PM and scAM concentrations were compared between sexes, while overall median values for scPM and scAM, as well as a ratio of scPM to scAM (P/A) were used as boundary values for sex identification. Neither scPM nor scAM concentrations were significantly different between the sexes and concentrations of a juvenile and sub-adult male overlapped with females, possibly indicating later sexual maturity in males. Boundary values for scAM concentrations and the P/A ratio predicted sex with 100% accuracy for females and 78% for males, while the accuracies for the scPM boundary value were lower. When only adult individuals are considered, scAM and P/A ratio boundaries are 100% accurate for both sexes. Therefore, scale hormone ratios show promise as a sex identification tool for Temminck’s pangolin, particularly applicable in forensic investigations on the pangolin trade.

Scientific and Regulatory Policy Committee Best Practices: Documentation of Sexual Maturity by Microscopic Evaluation in Nonclinical Safety Studies.

The sexual maturity status of animals in nonclinical safety studies can have a significant impact on the microscopic assessment of the reproductive system, the interpretation of potential test article-related findings, and ultimately the assessment of potential risk to humans. However, the assessment and documentation of sexual maturity for animals in nonclinical safety studies is not conducted in a consistent manner across the pharmaceutical and chemical industries. The Scientific and Regulatory Policy Committee of the Society of Toxicologic Pathology convened an international working group of pathologists and nonclinical safety scientists with expertise in the reproductive system, pathology nomenclature, and Standard for Exchange of Nonclinical Data requirements. This article describes the best practices for documentation of the light microscopic assessment of sexual maturity in males and females for both rodent and nonrodent nonclinical safety studies. In addition, a review of the microscopic features of the immature, peripubertal, and mature male and female reproductive system and general considerations for study types and reporting are provided to aid the study pathologist tasked with documentation of sexual maturity.

Low-Dose Exposure to Endocrine Disruptor Dichlorodiphenyltrichloroethane (DDT) Affects Transcriptional Regulation of Adrenal Zona Reticularis in Male Rats

The study examined transcriptional regulation of adrenal zona reticularis development in male Wistar rats exposed to low doses of endocrine disruptor dichlorodiphenyltrichloroethane (DDT) prenatally and postnatally. At pubertal age, zona reticularis demonstrated a retarded growth with a low proliferative activity of its cells. At this age, zona reticularis was characterized with overexpression of β-catenin by steroid-producing cells; a high percentage of cells with membrane and cytoplasmic localization of β-catenin, and reduced number of cells with nuclear β-catenin attesting to insufficient activation of Wnt signaling. Expression of transcriptional factor Oct4 by reticularis cells was down-regulated indicating their diminished proliferative potency. No significant alterations in Sonic Hedgehog expression were observed. Thus, DDT-provoked disorders of transcriptional regulation result in abnormal development of zona reticularis thereby disturbing sexual maturation in males.

Feeding on methoprene increases male accessory gland size and body protein in the Mexican fruit fly

AbstractMethoprene, a juvenile hormone analog, accelerates male sexual maturation in some pest species controlled through the Sterile Insect Technique (SIT). The SIT consists of the mass‐rearing, irradiation and release of insects into affected areas, where sterile males mate with wild females and render them infertile. Sterile males are held for 6 days in confinement before release, and they are often released before attaining sexual maturity. The use of methoprene during this time has been shown to increase male mating frequency. However, very little is known on the effects of methoprene on the reproductive physiology of tephritid pests, including male accessory gland size, whole body protein content, sperm transfer and female remating receptivity. Here we found that sterile Anastrepha ludens males fed methoprene with only a 1:24 protein to sugar diet had greater male mating frequency and bigger male accessory glands compared to males deprived of methoprene. Furthermore, positive effects of methoprene inclusion in the diet were found on the amount of sperm stored by females, and body protein content but only when males fed sugar only. Inclusion of methoprene in the diet did not affect remating propensity of wild females having mated with sterile males. Females mating with young 5‐day‐old males stored fewer sperm than females mating with older males regardless of diet. The use of methoprene as a pre‐release supplement can positively impact early sexual maturation, energy reserves and male reproductive organs of A. ludens males, thus supporting its use in SIT programmes controlling this pest.

Crucial Role of Juvenile Hormone Receptor Components Methoprene-Tolerant and Taiman in Sexual Maturation of Adult Male Desert Locusts.

Currently (2020), Africa and Asia are experiencing the worst desert locust (Schistocerca gregaria) plague in decades. Exceptionally high rainfall in different regions caused favorable environmental conditions for very successful reproduction and population growth. To better understand the molecular mechanisms responsible for this remarkable reproductive capacity, as well as to fill existing knowledge gaps regarding the regulation of male reproductive physiology, we investigated the role of methoprene-tolerant (Scg-Met) and Taiman (Scg-Tai), responsible for transducing the juvenile hormone (JH) signal, in adult male locusts. We demonstrated that knockdown of these components by RNA interference strongly inhibits male sexual maturation, severely disrupting reproduction. This was evidenced by the inability to show mating behavior, the absence of a yellow-colored cuticle, the reduction of relative testes weight, and the drastically reduced phenylacetonitrile (PAN) pheromone levels of the treated males. We also observed a reduced relative weight, as well as relative protein content, of the male accessory glands in Scg-Met knockdown locusts. Interestingly, in these animals the size of the corpora allata (CA), the endocrine glands where JH is synthesized, was significantly increased, as well as the transcript level of JH acid methyltransferase (JHAMT), a rate-limiting enzyme in the JH biosynthesis pathway. Moreover, other endocrine pathways appeared to be affected by the knockdown, as evidenced by changes in the expression levels of the insulin-related peptide and two neuroparsins in the fat body. Our results demonstrate that JH signaling pathway components play a crucial role in male reproductive physiology, illustrating their potential as molecular targets for pest control.

Seasonal changes in maturational status, body condition, and population structure in the Moroccan Atlantic Sardine Sardina pilchardus (Teleostei: Clupeidae) from Safi fishing area

Aspects of reproduction and population structure were investigated between June 2017 to May 2018 in sardines, Sardina pilchardus (Walbaum, 1792) from the Safi fishing area. The sex ratio was generally in favor of males (χ2=19.50). Out of 3252 total specimens sampled, 1404 were females (46.00%), 1648 males 50.68%) and 200 immatures (6.15%). The immatures were best represented in the small size classes, between 8 and 12 cm. This study showed that sardines can breed throughout the year with a peak breeding season between November and February. The gonado-somatic index (GSI) and the condition coefficient (CC) evolved almost invariably. The volumetric absolute body condition index [kv= Fresh total body mass (g)/total body volume (cm3)] showed two peaks, which are discriminately sex dependent. For females, the peaks are concomitantly observed in September and April while for males, these are shown in June and February. Moreover, the morphometric index (kn) showed a single peak in January and September for reproductive males and females, respectively. As regards the non-reproductive individuals the males have two peaks in June and December or females, they have one peak in November. Additionally, the GSI showed a single peak in February. The size at first sexual maturity in males and females was 16.1 cm and 16.5 cm, respectively.

Life history of the freshwater microturbellarian Macrostomum velastylum (Macrostomorpha) in the Neotropical region

ABSTRACT The genus Macrostomum (Platyhelminthes: Macrostomorpha) is a group of cosmopolitan free-living flatworms that occurs in a wide range of habitats. In our study, individuals of Macrostomum velastylum were collected from the Sagastume stream (33°38ʹ34ʺS; 58°49ʹ63ʺW) Entre Ríos Province, Argentina, during 2016. They were kept in laboratory at room temperature in order to study population parameters (1, fecundity; 2, hatching rate and hatching time; 3, male sexual maturation time; and 4, longevity). The results show that this species laid 1.5 eggs per day per individual, the hatching rate was 85% and most eggs hatched between the first and second week after laying. The maturation time showed an extensive range of time to reach sexual maturation. The average longevity was 96 ± 33 days. Considering the laboratory conditions and the scarce information on life cycles on Macrostomum species, these results are promising for future interspecific comparative studies.

Direct glia-to-neuron transdifferentiation gives rise to a pair of male-specific neurons that ensure nimble male mating.

Sexually dimorphic behaviours require underlying differences in the nervous system between males and females. The extent to which nervous systems are sexually dimorphic and the cellular and molecular mechanisms that regulate these differences are only beginning to be understood. We reveal here a novel mechanism by which male-specific neurons are generated in Caenorhabditis elegans through the direct transdifferentiation of sex-shared glial cells. This glia-to-neuron cell fate switch occurs during male sexual maturation under the cell-autonomous control of the sex-determination pathway. We show that the neurons generated are cholinergic, peptidergic, and ciliated putative proprioceptors which integrate into male-specific circuits for copulation. These neurons ensure coordinated backward movement along the mate's body during mating. One step of the mating sequence regulated by these neurons is an alternative readjustment movement performed when intromission becomes difficult to achieve. Our findings reveal programmed transdifferentiation as a developmental mechanism underlying flexibility in innate behaviour.