Visualizing the organization and differentiation of the male-specific nervous system of C. elegans

Sex differences in the brain are prevalent throughout the animal kingdom and particularly well appreciated in the nematode C. elegans, where male animals contain a little studied set of 93 male-specific neurons. To make these neurons amenable for future study, we describe here how a multicolor reporter transgene, NeuroPAL, is capable of visualizing the distinct identities of all male specific neurons. We used NeuroPAL to visualize and characterize a number of features of the male-specific nervous system. We provide several proofs of concept for using NeuroPAL to identify the sites of expression of gfp-tagged reporter genes and for cellular fate analysis by analyzing the effect of removal of several developmental patterning genes on neuronal identity acquisition. We use NeuroPAL and its intrinsic cohort of more than 40 distinct differentiation markers to show that, even though male-specific neurons are generated throughout all four larval stages, they execute their terminal differentiation program in a coordinated manner in the fourth larval stage. This coordinated wave of differentiation, which we call “just-in-time" differentiation, couples neuronal maturation programs with the appearance of sexual organs.

Composition, habitat preference and seasonal variation of malaria vector larval and pupa stage in Akure North Local Government Area of Ondo State, Nigeria

Background The study of habitat preference and identification of malaria vector is one of the important steps in malaria control. Knowledge of local Anopheles mosquitoes capable of transmitting malaria parasites has contributed largely to the reduction in the menace caused by malaria infection. This present study examined the habitat nature and identified the species of Anopheles mosquitoes involved in malaria parasites transmission in the study area. Monthly collection and identification of the fourth larval stage was carried out from October 2018 to September 2019. Result The prevalence of An. gambiae complex and An. funestus larvae was 95.86 and 4.15%, respectively. The highest (14.17%) and the least (4.25%) number of larvae were collected in the month of November and May, respectively. Out of the total number of Anopheles mosquito larvae collected during the wet season, 69.77% of the larvae was collected from the clean habitat, while 30.23% was collected from the dirty habitats. During the dry season, the larvae dwell more in dirty aquatic habitat, with 64.74% of the larvae collected from the dirty habitats, while 35.27% was recorded from clean habitats. Statistically, there was no significant difference in the electrical conductivity when comparing both seasons (P = 0.19; X2 = 53.14). The average recorded electrical conductivity in dry and wet seasons were 350.76 µS/cm and 178.91 µS/cm, respectively. The pH recorded in dry and wet seasons were 6.78 and 7.04, respectively. There was no significant difference in the pH when both seasons were compared (P = 0.13; X2 = 54.89). The total dissolve solid where not significant different (P = 0.58; X2 = 13.35) when both seasons were compared. The temperature (P = 0.04; X2 = 43.54) and dissolve oxygen (P = 0.00; X2 = 30.09) were significantly different comparing dry and wet seasons in all the habitats where the immature stages of Anopheles mosquitoes were collected. Conclusion The study revealed major vector of malaria parasite in the study location, also the pattern of their breeding during dry and rainy season which is influenced by some selected ecological factors.

Scaling and development of elastic mechanisms: the tiny strikes of larval mantis shrimp

ABSTRACT Latch-mediated spring actuation (LaMSA) is used by small organisms to produce high acceleration movements. Mathematical models predict that acceleration increases as LaMSA systems decrease in size. Adult mantis shrimp use a LaMSA mechanism in their raptorial appendages to produce extremely fast strikes. Until now, however, it was unclear whether mantis shrimp at earlier life-history stages also strike using elastic recoil and latch mediation. We tested whether larval mantis shrimp (Gonodactylaceus falcatus) use LaMSA and, because of their smaller size, achieve higher strike accelerations than adults of other mantis shrimp species. Based on microscopy and kinematic analyses, we discovered that larval G. falcatus possess the components of, and actively use, LaMSA during their fourth larval stage, which is the stage of development when larvae begin feeding. Larvae performed strikes at high acceleration and speed (mean: 4.133×105 rad s−2, 292.7 rad s−1; 12 individuals, 25 strikes), which are of the same order of magnitude as for adults – even though adult appendages are up to two orders of magnitude longer. Larval strike speed (mean: 0.385 m s−1) exceeded the maximum swimming speed of similarly sized organisms from other species by several orders of magnitude. These findings establish the developmental timing and scaling of the mantis shrimp LaMSA mechanism and provide insights into the kinematic consequences of scaling limits in tiny elastic mechanisms.

Visualizing the organization and differentiation of the male-specific nervous system of C. elegans

Sex differences in the brain are prevalent throughout the animal kingdom and particularly well appreciated in the nematode C. elegans. While 294 neurons are shared between the two sexes, the nervous system of the male contains an additional 93 male-specific neurons, most of which have received very little attention so far. To make these neurons amenable for future study, we describe here how a multicolor, multipromoter reporter transgene, NeuroPAL, is capable of visualizing the distinct identities of all male specific neurons. We used this tool to visualize and characterize a number of features of the male-specific nervous system. We provide several proofs of concept for using NeuroPAL to identify the sites of expression of gfp-tagged reporter genes. We demonstrate the usage of NeuroPAL for cellular fate analysis by analyzing the effect of removal of developmental patterning genes, including a HOX cluster gene (egl-5), a miRNA (lin-4) and a proneural gene (lin-32/Ato), on neuronal identity acquisition within the male-specific nervous system. We use NeuroPAL and its intrinsic cohort of more than 40 distinct differentiation markers to show that, even though male-specific neurons are generated throughout all four larval stages, they execute their terminal differentiation program in a coordinated manner in the fourth larval stage that is concomitant with male tale retraction. This wave of differentiation couples neuronal maturation programs with the appearance of sexual organs. We call this wave 'just-in-time' differentiation by its analogy to the mechanism of 'just-in-time' transcription of metabolic pathway genes.

Aleyrodes lonicerae Walker (Hemiptera: Aleyrodidae)’nın Rosa sp. Üzerinde Biyolojik Özellikleri ve Ölümü Esas Alan Yaşam Çizelgeleri

Biology of the Lonicera whitefly, Aleyrodes lonicerae Walker (Hemiptera: Aleyrodidae) were studied on rose, Rosa sp. (Rosaceae) plants. Whitefly adults were collected from Mercurialis annua L. (Euphorbiaceae) plants in Adana. The development duration of egg, first, second, third, fourth larval (pupa) stages, total of A. lonicerae on Rosa sp. plants at 20°C were 8.44, 5.44, 5.50, 4.50, 5.19 and 29.07 days for the females and 8.15, 5.46, 5.92, 4.92, 5.38, 29.83 days for the males respectively. The development duration of egg, first, second, third, fourth larval (pupa) stages, total of A. lonicerae on Rosa sp. plants at 25°C were 8.00, 1.67, 2.33, 2.67, 9.67, 24.34 days for the females and 7.67, 2.33, 2.33, 3.33, 7.83 and 23.49 days for the males respectively. The mortality rate (%) of egg, first, second, third, fourth larval (pupae) stages of A. lonicerae at 20 and 25°C temperatures were 14.70, 13.97, 25.00, 20.58, 4.41; 2.89, 24.65, 26.08, 20.28, 13.06 respectively. The biggest k values at 20 and 25°C on rose plants were 0.2553 for the third larval stage and 0.3010 for the fourth larval stage, respectively.

Global accumulation of circRNAs during aging in Caenorhabditis elegans

SummaryCircular RNAs (CircRNAs) are a newly appreciated class of RNAs that lack free 5´ and 3´ ends, are expressed by the thousands in diverse forms of life, and are mostly of enigmatic function. Ostensibly due to their resistance to exonucleases, circRNAs are known to be exceptionally stable. Here, we examined the global profile of circRNAs in C. elegans during aging by performing ribo-depleted total RNA-seq from the fourth larval stage (L4) through 10-day old adults. Using stringent bioinformatic criteria and experimental validation, we annotated 1,166 circRNAs, including 575 newly discovered circRNAs. These circRNAs were derived from 797 genes with diverse functions, including genes involved in the determination of lifespan. A massive accumulation of circRNAs during aging was uncovered. Many hundreds of circRNAs were significantly increased among the aging time-points and increases of select circRNAs by over 40-fold during aging were quantified by qRT-PCR. The age-accumulation of circRNAs was not accompanied by increased expression of linear RNAs from the same host genes. We attribute the global scale of circRNA age-accumulation to the high composition of postmitotic cells in adult C. elegans, coupled with the high resistance of circRNAs to decay. These findings suggest that the exceptional stability of circRNAs might explain age-accumulation trends observed from neural tissues of other organisms, which also have a high composition of post-mitotic cells. Given the suitability of C. elegans for aging research, it is now poised as an excellent model system to determine if there are functional consequences of circRNA accumulation during aging.

A longitudinal study of Caenorhabditis elegans larvae reveals a novel locomotion switch, regulated by Gαs signaling

Despite their simplicity, longitudinal studies of invertebrate models are rare. We thus sought to characterize behavioral trends of Caenorhabditis elegans, from the mid fourth larval stage through the mid young adult stage. We found that, outside of lethargus, animals exhibited abrupt switching between two distinct behavioral states: active wakefulness and quiet wakefulness. The durations of epochs of active wakefulness exhibited non-Poisson statistics. Increased Gαs signaling stabilized the active wakefulness state before, during and after lethargus. In contrast, decreased Gαs signaling, decreased neuropeptide release, or decreased CREB activity destabilized active wakefulness outside of, but not during, lethargus. Taken together, our findings support a model in which protein kinase A (PKA) stabilizes active wakefulness, at least in part through two of its downstream targets: neuropeptide release and CREB. However, during lethargus, when active wakefulness is strongly suppressed, the native role of PKA signaling in modulating locomotion and quiescence may be minor.

Larval Hysterothylacium sp. (Nematoda, Anisakidae) and trematode metacercariae from the amphipod Paracorophium excavatum (Corphiidae) in New Zealand

Previously undescribed fourth-stage larvae of anisakid nematodes were found in the haemocoel of the amphipod Paracorophium excavatum (Thomson, 1884) (Corophiidae) in New Zealand. Morphological examination by light microscopy showed that the worms belonged to a species of Hysterothylacium Ward et Magath, 1917, based on several characters including the presence of interlabia, the location of the excretory pore posterior to the nerve ring, and the characteristics of the intestinal caecum and ventricular appendix. Interestingly, several male specimens showed precocious sexual development. This is the first record of fourth larval stage and precocious adult male specimens of Hysterothylacium in an invertebrate host, as well as the first record of anisakid larvae in New Zealand crustaceans. In addition, metacercariae of two trematode species, Coitocaecum parvum and Microphallus sp., are recorded for the first time from the amphipod P. excavatum.