Larval Formation Research Articles

Deciphering anhydrobiosis and plant parasitism of the wheat seed gall nematode, Anguina tritici through transcriptomic analysis

The wheat seed gall nematode (Anguina tritici L.) poses a significant threat to wheat and barley production. Central to its survival is the ability to endure desiccation through anhydrobiosis, setting it apart from other nematodes. Unraveling the molecular mechanisms governing anhydrobiosis and plant parasitism in A. tritici is crucial for devising effective management strategies. A comprehensive transcriptomic analysis was conducted to elucidate the genetic pathways involved in these processes. Employing next-generation sequencing technologies, gene expression profiling was performed across three developmental stages, namely anhydrobiotic J2, revived J2 and the adult. Transcriptomic profiling yielded 139,002 transcripts in anhydrobiotic J2s, 156,731 in revived J2s, and 80,282 in adult stages, with a cumulative assembly size of 133.2 Mb. Differential gene expression analysis revealed that 1223 genes were significantly upregulated whereas 1934 genes were downregulated in anhydrobiotic J2s in comparison to revived J2s. Comparative transcriptomic analysis across nematode species highlighted conserved and species-specific genes. Functional annotation identified key genes associated with anhydrobiosis, plant parasitism, glycosylation, and longevity mechanisms. Real-time PCR validation corroborated differential expression patterns. The present study provides gene homologs and longevity pathways, which indicate similarity of the mechanism of dauer larva formation and survival strategies to that of Caenorhabditis elegans. Comprehensive understanding of the molecular basis for survival and parasitic strategies of A. tritici, shall provide potential targets for novel control interventions to mitigate nematode's impact on wheat crops.

Aspartame Causes Developmental Defects and Teratogenicity in Zebra Fish Embryo: Role of Impaired SIRT1/FOXO3a Axis in Neuron Cells.

Aspartame, a widely used artificial sweetener, is present in many food products and beverages worldwide. It has been linked to potential neurotoxicity and developmental defects. However, its teratogenic effect on embryonic development and the underlying potential mechanisms need to be elucidated. We investigated the concentration- and time-dependent effects of aspartame on zebrafish development and teratogenicity. We focused on the role of sirtuin 1 (SIRT1) and Forkhead-box transcription factor (FOXO), two proteins that play key roles in neurodevelopment. It was found that aspartame exposure reduced the formation of larvae and the development of cartilage in zebrafish. It also delayed post-fertilization development by altering the head length and locomotor behavior of zebrafish. RNA-sequencing-based DEG analysis showed that SIRT1 and FOXO3a are involved in neurodevelopment. In silico and in vitro analyses showed that aspartame could target and reduce the expression of SIRT1 and FOXO3a proteins in neuron cells. Additionally, aspartame triggered the reduction of autophagy flux by inhibiting the nuclear translocation of SIRT1 in neuronal cells. The findings suggest that aspartame can cause developmental defects and teratogenicity in zebrafish embryos and reduce autophagy by impairing the SIRT1/FOXO3a axis in neuron cells.

The ACE inhibitor captopril inhibits ACN-1 to control dauer formation and aging.

The renin-angiotensin-aldosterone system (RAAS) plays a well-characterized role regulating blood pressure in mammals. Pharmacological and genetic manipulation of the RAAS has been shown to extend lifespan in Caenorhabditis elegans, Drosophila and rodents, but its mechanism is not well defined. Here, we investigate the angiotensin-converting enzyme (ACE) inhibitor drug captopril, which extends lifespan in worms and mice. To investigate the mechanism, we performed a forward genetic screen for captopril-hypersensitive mutants. We identified a missense mutation that causes a partial loss of function of the daf-2 receptor tyrosine kinase gene, a powerful regulator of aging. The homologous mutation in the human insulin receptor causes Donohue syndrome, establishing these mutant worms as an invertebrate model of this disease. Captopril functions in C. elegans by inhibiting ACN-1, the worm homolog of ACE. Reducing the activity of acn-1 via captopril or RNA interference promoted dauer larvae formation, suggesting that acn-1 is a daf gene. Captopril-mediated lifespan extension was abrogated by daf-16(lf) and daf-12(lf) mutations. Our results indicate that captopril and acn-1 influence lifespan by modulating dauer formation pathways. We speculate that this represents a conserved mechanism of lifespan control.

Influence of Tempetature on Viability and Deveplopment of Heterakis gallinarum (Nematoda, Heterakidae) Eggs

Pinworms of the genus Heterakis Dujardin, 1845 parasitize a wide range of hosts, including a number of species of domestic and wild birds. These nematodes are ecologically adapted to the climatic conditions of many geographical zones, which contributes to their widespread distribution. The aim of the work was to investigate the influence of different temperature regimes at laboratory conditions on the growth, development and viability of eggs isolated from the gonads of female nematodes Heterakis gallinarum Schrank, 1788. The conducted studies established that, depending on the cultivation temperature, nematode eggs developed from 6 to 56 days, and their survival rate was from 67.7 to 83.7 %. The temperature of 25 °С was the most favourable for the development of H. gallinarum eggs, the development lasted 12 days and the highest number of eggs with motile infective larvae was formed (83.7 %). It was found that the period of egg development in cultures gradually decreased with increasing temperature: it was 56 days at 15 °C, 18 days at 20 °C, 12 days at 25 °C and 6 days at 30 °C. The survival rate of H. gallinarum eggs gradually increased with increasing temperature in regimes of 15 °С, 20 °С and 25 °С to 67.7 %, 80.7 % and 83.7 %, respectively. At a temperature of 30 °C, egg survival decreased slightly to 78.7 %. It was found that the development of H. gallinarum eggs from the zygote stage to the formation of motile infective larvae, depending on the temperature regime of cultivation, is accompanied by a decrease in egg length by 4.9–5.4 %, an increase in egg width by 4.1–7.6 % and a thinning of the shell by 9.5–28.6 %. Under different temperature regimes, the morphometric parameters of eggs during their development differ in terms of their length, width and shell thickness.

Inhibition of biofilm formation and settlement of barnacle larvae by a biosurfactant produced from a marine biofilm-forming Exiguobacterium sp. R58

Natural product based antifouling strategies are promising alternatives for achieving biofouling control with minimal environmental burden. Although microbial biosurfactants have shown antimicrobial and antibiofilm activities, their efficacy on settlement of barnacles, among the most problematic of biofouling organisms in the marine environment, has not be evaluated. Biofilm-forming bacteria isolated from the seawater cooling system of a power plant were screened for biosurfactant production and one of the promising strains was identified as Exiguobacterium sp. R58. Production, characterization and anti-biofouling activity of the biosurfactant was determined. Emulsifying activity of 68–89% was achieved at 4−100 °C, 2–12% salinity and 2–12 pH. Biofilm formation by Escherichia coli, Staphylococcus aureus, Salinococcus sp., and Marinobacter sp. was strongly inhibited (80–92%) in the presence of 2000 μg/mL biosurfactant. Cypris larval settlement was impaired by the biosurfactant without causing mortality. Biosurfactant coated surfaces prevented biofilm formation and cypris settlement. Adhesion of bacteria on biosurfactant coated surfaces was 75–93% lower as compared to control. Cypris settlement was inhibited completely in Petri dishes coated with 5.6–22.7 mg/cm2 in no-choice assays and 1.3 mg/cm2 in choice assays. Antibiofouling activity of the biosurfactant was related to surface modification, thus promising for developing non-toxic antifouling materials.

LIFE CYCLE AND DEVELOPMENT PERIODS OF OIL PALM POLLINATING WEEVIL, ELAEIDOBIUS KAMERUNICUS FAUST, 1878 (COLEOPTERA: CURCULIONIDAE) FROM OIL PALM PLANTATIONS IN MALAYSIA

The pollinating weevil, Elaeidobius kamerunicus, was introduced to Malaysia in 1981 to foster the production of oil palm fruit bunches. The weevil plays a significant role in the pollination of oil palm. This study aims to determine the life cycle, development period, body size and longevity of oil palm pollinating weevils in four different types of soils in Malaysia, namely: shallow peat soil [Malaysian Palm Oil Board (MPOB) Teluk Intan], deep peat soil (MPOB Sessang), mineral soil (MPOB Long Danau) and clay soil [Federal Land Development Authority (FELDA) Sahabat]. The result from the study conducted in MPOB, Bangi showed that the total weevil life cycle and development period ranged from 1-14 days, whereby the eggs hatched in 0-1 day, formation of larva I was around 1-3 days, larva II around 2-10 days, larva III around 4-12 days, pupae around 6-14 days and adult weevil around 8-14 days, without any significant differences between the four populations in different soil types from different plantations. About 80 per cent of male and female weevils can live an average of 33 and 32 days, respectively. However, there were no significant differences in longevity between male and female adults. Meanwhile, the morphological size measured differed significantly among the life stages between the four weevil populations. Overall, there was a slight variation, however, there was no significant difference in the life cycle, development period and longevity between the four weevil populations in different types of soil from different plantations in Malaysia. Keywords: Life history, longevity, morphological size, soil types, agriculture.

On the haem auxotrophy of the soft tick Ornithodoros moubata

Genomes of ticks display reductions, to various extents, in genetic coding for enzymes of the haem biosynthetic pathway. Here, we mined available transcriptomes of soft tick species and identified transcripts encoding only half of the enzymes involved in haem biosynthesis. Transcripts identified across most species examined were those coding for porphobilinogen synthase, coproporphyrinogen oxidase, protoporphyrinogen oxidase, and ferrochelatase. Genomic retention of porphobilinogen synthase seems to be soft tick-restricted as no such homologue has been identified in any hard tick species. Bioinformatic mining is thus strongly indicative of the lack of biochemical capacity for de novo haem biosynthesis, suggesting a requirement for dietary haem. In the hard tick Ixodes ricinus, depletion of dietary haem, i.e. serum feeding, leads to oviposition of haem-free eggs, with no apparent embryogenesis and larvae formation. In this work, we show that serum-fed Ornithodoros moubata females, unlike those of I. ricinus, laid haem-containing eggs similarly to blood-fed controls, but only by a small proportion of the serum-fed females. To enhance the effect of dietary haem depletion, O. moubata ticks were serum-fed consecutively as last nymphal instars and females. These females laid eggs with profoundly reduced haem deposits, confirming the host origin of the haem. These data confirm the ability of soft ticks to take up and allocate host haem to their eggs in order to drive reproduction of the ticks.

Ixodes ricinus ticks have a functional association with Midichloria mitochondrii.

In addition to being vectors of pathogenic bacteria, ticks also harbor intracellular bacteria that associate with ticks over generations, aka symbionts. The biological significance of such bacterial symbiosis has been described in several tick species but its function in Ixodes ricinus is not understood. We have previously shown that I. ricinus ticks are primarily inhabited by a single species of symbiont, Midichloria mitochondrii, an intracellular bacterium that resides and reproduces mainly in the mitochondria of ovaries of fully engorged I. ricinus females. To study the functional integration of M. mitochondrii into the biology of I. ricinus, an M. mitochondrii-depleted model of I. ricinus ticks was sought. Various techniques have been described in the literature to achieve dysbiosed or apo-symbiotic ticks with various degrees of success. To address the lack of a standardized experimental procedure for the production of apo-symbiotic ticks, we present here an approach utilizing the ex vivo membrane blood feeding system. In order to deplete M. mitochondrii from ovaries, we supplemented dietary blood with tetracycline. We noted, however, that the use of tetracycline caused immediate toxicity in ticks, caused by impairment of mitochondrial proteosynthesis. To overcome the tetracycline-mediated off-target effect, we established a protocol that leads to the production of an apo-symbiotic strain of I. ricinus, which can be sustained in subsequent generations. In two generations following tetracycline administration and tetracycline-mediated symbiont reduction, M. mitochondrii was gradually eliminated from the lineage. Larvae hatched from eggs laid by such M. mitochondrii-free females repeatedly performed poorly during blood-feeding, while the nymphs and adults performed similarly to controls. These data indicate that M. mitochondrii represents an integral component of tick ovarian tissue, and when absent, results in the formation of substandard larvae with reduced capacity to blood-feed.

Etlingera elatior extract inhibits early developmental stage of Fasciola gigantica egg in vitro

The use of plants as natural anthelmintic is quite promising for parasite control. In this report, we evaluate the activity of Etlingera elatior to Fasciola gigantica eggs in vitro. The eggs were collected from naturally-infected bovine in the Ampel Abbatoir, Boyolali, Central Java. The eggs were exposed to E. elatior ethanolic extract in different concentrations i.e., 5%, 2.5% and 1.25%. Fluconix 340 in the equal concentrations was positive control of anthelmintic and distilled water served as negative treatment. The eggs were placed in the dark until 9 days and observed under the light microscope on days 5 and 9. The results showed that E. elatior in the concentration of 5%, 2.5% and 1.25% significantly inhibited the initial development of F. gigantica compared to the negative control (water) on days 5 and 9 treatments (P<0.05). The E. elatior effectively inhibits morulation and larva formation. Fluconix 340 5%, 2.5% and 1.25% were possessing higher ovicidal activities compared to E. elatior since day 5 of treatment. E. elatior showed effective inhibition to the initial development of F. gigantica egg in vitro.

Larvicidal and Growth Inhibitory Activities of Ageratum houstonianum (Mill, 1768) Against the Dengue Vector Aedes aegypti (Linnaeus, 1762)

In the present work, Ageratum houstonianum leaf acetone extract was tested for the larvicidal and growth inhibitory activity against the third instar larvae of the Dengue vector, Aedes aegypti. The extract showed larvicidal activity with LC50 and LC90 values of 204.79 and 277.57 mg/L, respectively. The larval mortality was increased during subsequent days of treatment. The extract adversely affected larval development, causing a significant reduction in both the formation of fourth instar larvae and pupae. Also, the extract increased the larval duration of Ae. aegypti third instar larvae indicating growth inhibitory activities of the extract. The results showed dose-dependent effects of the A. houstonianum leaf acetone extract; treatment at higher concentrations inhibited the growth and reduced the viability. This resulted in a decrease in the larval growth index. GC-MS analysis revealed the presence of precocene I and precocene II along with many other components which affect the survival and growth of the insects adversely. This explores the potential of A. houstonianum in the management of Ae. aegypti.

Insulin/IGF signaling regulates presynaptic glutamate release in aversive olfactory learning.

Insulin/insulin-like growth factor (IGF) receptor signaling (IIS) supports context-dependent learning in vertebrates and invertebrates. Here, we identify cell-specific mechanisms of IIS that integrate sensory information with food context to drive synaptic plasticity and learning. In the nematode Caenorhabditis elegans, pairing food deprivation with an odor such as butanone suppresses attraction to that odor. We find that aversive olfactory learning requires the insulin receptor substrate (IRS) protein IST-1 and atypical signaling through the insulin/IGF-1 receptor DAF-2. Cell-specific knockout and rescue demonstrate that DAF-2 acts in the AWCON sensory neuron, which detects butanone, and that learning preferentially depends upon the axonally localized DAF-2c isoform. Acute food deprivation increases DAF-2 levels in AWCON post-transcriptionally through an insulin- and insulin receptor substrate-1 (ist-1)-dependent process. Aversive learning alters the synaptic output of AWCON by suppressing odor-regulated glutamate release in wild-type animals, but not in ist-1 mutants, suggesting that axonal insulin signaling regulates synaptic transmission to support aversive memory.

Effect of temperature on embryogenesis of Trichuris ovis during in vitro cultivation

One of the priority tasks of animal husbandry development is environmental protection from contamination of environmental objects with eggs, larvae of helminths, cysts, and oocysts of intestinal parasites, which are dangerous for animals and humans. For this purpose, it is relevant to determine the leading factors and ways of transmission of pathogens of parasitoses, the terms of their development, and survival under various abiotic influences in the conditions of certain climatic regions. The work aimed to determine the influence of the temperature factor on the embryonic development of nematodes of the species Trichuris ovis, parasitizing sheep. It was established that the embryogenesis of T. ovis varies from 27 to 36 days, depending on the temperature regime, where the development of eggs occurs in 6 stages. The duration of each stage of embryonic development of trichurises of this species also depends on temperature. The temperature at 25 °C was the most susceptible for developing T. ovis eggs in laboratory conditions, where 80.67 % of invasive larvae were formed on the 36th day. At this temperature, the zygote stage lasted up to 9 days, crushing and formation of blastomeres – up to 12 days, bean-like embryo – up to 18 days, tadpole-like embryo – up to 24 days, and larva formation – up to 30 days. The temperature of 20 °С was less susceptible to developing T. ovis eggs, where 77.0 % of invasive eggs were formed on the 33rd day of cultivation. At this temperature, the zygote stage lasted up to 9 days, crushing and formation of blastomeres – up to 15 days, bean-like embryo – up to 18 days, tadpole-like embryo – up to 24 days, and larva formation – up to 33 days. At a temperature of 30 °С, the term of embryogenesis of T. ovis turned out to be the shortest – 27 days, but at the same time, the smallest number of invasive eggs was formed – 71.0 %. At this temperature, the zygote stage lasted up to 6 days, crushing and formation of blastomeres – up to 12 days, bean-like embryo – up to 15 days, tadpole-like embryo – up to 21 days, and larva formation – up to 24 days. The obtained research results expand the existing scientific data and will also allow us to effectively plan the timing of measures for destroying pathogens of sheep trichurosis in the embryonic stages of development in the external environment.

Viability of exogenous stages of development of the causative agent of trichu-riasis of dogs under the influence of temperature

Urbanization processes to one degree or another occur in all regions of the planet. Large, small cities and megacities are created, leading to an urban ecosystem with unique abiotic and biotic factors. All this significantly affects the fauna, stability and viability of parasites of domestic dogs, which are representatives of the urban environment. The work aimed to establish the degree of viability of exogenous stages of development of Trichuris vulpis, parasitizing dogs, under the influence of different temperatures. It was established that in laboratory conditions, depending on temperature fluctuations (23 °C–29 °C), the development period of trichurises eggs to the invasive stage ranged from 15 to 27 days. At a 23 °C for 27 days, 74.0 % of invasive T. vulpis eggs were formed. At this temperature, 26.0 % of eggs died during their embryogenesis. At a temperature of 25 °C, the process of egg development to the invasive stage lasted 24 days, where 77.7 % of viable eggs were formed. At this temperature, 22.3 % of trichurises eggs died. As the temperature rises, the egg development period gradually shortens and is 18 days at a temperature of 27 °C, and 15 days at a temperature of 29°C. At the same time, the number of formation of viable invasive eggs decreased and amounted to 81.0 and 64.3 %, respectively, and the percentage of egg death increased to 19.0 and 35.7 %. The terms of formation of various stages of egg development in embryogenesis depended on the temperature, where as its indicators increased, the terms of these stages also shortened. The term of the zygote stage was shortened from 9 to 6 days, the stage of blastomere splitting – from 12 to 6 days, the leguminous embryo stage – from 15 to 6 days, the tadpole embryo stage – from 21 to 9 days, the larval stage – from 24 to 12 days, formation of a mobile larva – from 27 to 15 days. The conducted experimental studies expand the already existing data on the stability of the eggs of trichurises, which parasitize dogs, concerning the influence of temperature in the environment, and also make it possible to correctly establish the terms of preventive measures and prevent the infection of animals through environmental objects.

Opposing directions of stage-specific body shape change in a close relative of C. elegans

BackgroundBody size is a fundamental organismal trait. However, as body size and ecological contexts change across developmental time, evolutionary divergence may cause unexpected patterns of body size diversity among developmental stages. This may be particularly evident in polyphenic developmental stages specialized for dispersal. The dauer larva is such a stage in nematodes, and Caenorhabditis species disperse by traveling on invertebrate carriers. Here, we describe the morphology of a stress-resistant, dauer-like larval stage of the nematode Caenorhabditis inopinata, whose adults can grow to be nearly twice as long as its close relative, the model organism C. elegans.ResultsWe find that a dauer-like, stress-resistant larval stage in two isolates of C. inopinata is on average 13% shorter and 30% wider than the dauer larvae of C. elegans, despite its much longer adult stage. Additionally, many C. inopinata dauer-like larvae were ensheathed, a possible novelty in this lineage reminiscent of the infective juveniles of parasitic nematodes. Variation in dauer-like larva formation frequency among twenty-four wild isolates of C. inopinata was also observed, although frequencies were low across all isolates (< 2%), with many isolates unable to produce dauer-like larvae under conventional laboratory conditions.ConclusionMost Caenorhabditis species thrive on rotting plants and disperse on snails, slugs, or isopods (among others) whereas C. inopinata is ecologically divergent and thrives in fresh Ficus septica figs and disperses on their pollinating wasps. While there is some unknown factor of the fig environment that promotes elongated body size in C. inopinata adults, the small size or unique life history of its fig wasp carrier may be driving the divergent morphology of its stress-resistant larval stages. Further characterization of the behavior, development, and morphology of this stage will refine connections to homologous developmental stages in other species and determine whether ecological divergence across multiple developmental stages can promote unexpected and opposing changes in body size dimensions within a single species.

Features of the exogenic development of Passalurus ambiguus (Nematoda, Oxyuroidae) at different temperature regimes

Passalurosis is a prevalent disease among helminthiases of domestic rabbits. This invasion is caused by the nematode Passalurus ambiguus (Nematoda, Oxyuroidae), which is cosmopolitan and localized in the cecum and colon of rabbits. Passalurosis is highly contagious and capable of unlimited spread, due to the biological characteristics of its pathogen, such as the conditions that ensure maximum preservation of parasites at exogenous stages of their development. Experimental research in the laboratory established the timing of development of P. ambiguus eggs isolated from the gonads of female helminths, depending on temperature regimes and features of their growth and development. According to the morphological features of Passalurus eggs, four stages were distinguished in their exogenous development: zygote, cleavage and formation of blastomeres, formation of larvae and motile larvae. Depending on the cultivation temperature, the duration of embryogenesis ranged from 4 to 9 days, and egg viability ranged from 59.3% to 72.7%. The most favourable temperature regime for the development of P. ambiguus eggs was the temperature of 35 °C, at which 72.7% of eggs with motile larvae were formed within 4 days. At this temperature, the zygote stage lasted for 1 day of cultivation, the stage of cleaving and formation of blastomeres occurred on days 1–2, the stage of larval formation on days 1–3, and the stage of formation of motile larva on days 3–4. At lower temperatures, the term of development of Passalurus eggs increased, and the number of viable eggs decreased. At temperatures of 30 °С and 25 °С, the development of Passalurus eggs took place during 5 and 7 days, respectively, and the viability was 66.7% and 62.7%. At these temperatures, the zygote stage lasted 1–2 and 1–3 days, the stage of cleaving and formation of blastomeres occurred on days 1–3 and 1–4, the stage of larval formation lasted from days 2–4 and 2–6, and the stage of formation of motile larvae took place on days 3–5 and 4–7, respectively. The least favourable temperature for the development of P. ambiguus eggs was the temperature of 20 °С, at which the formation of motile larvae occurred in 9 days, and their viability was only 59.3%. At this temperature, the zygote stage lasted 1–4 days, the stage of cleaving and blastomere formation occurred on days 2–6, and the larval formation stage on days 3–8, and the motile larval stage happened on days 5–9. The growth and development of P. ambiguus eggs was accompanied by significant changes in morphometric parameters, such as the increase in egg width and thinning of egg shell at the egg shell plug. The obtained data will allow preventive measures to be effectively implemented on rabbit farms that are susceptible to pinworms, taking into account the terms of exogenous development of pathogens in different seasons.

Organophosphate-based flame retardant (tris(1,3-dichloro-2-propyl) phosphate) reduces fecundity and impairs embryonic development in marine invertebrates

Context It is important to understand how marine invertebrates may be affected by tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), as an organophosphorus flame retardant. Aim The present research verified the hypothesis that TDCIPP would adversely affect the growth, development and reproduction of Crepidula onyx (phylum Mollusca) and Tigriopus japonicus (phylum Arthropoda). Methods Effects of chronic exposure for the whole life cycle were examined at two concentrations of TDCIPP chosen on the basis of results from preliminary range-finding test. Key results Exposure to 1 and 10 μg L−1 of TDCIPP significantly reduced larval and juvenile survival rate and shell length in C. onyx. TDCIPP caused adverse reproductive effects, including abnormal embryonic development, which led to non-viable broods and the malformation of larvae. Exposure to TDCIPP resulted in a 100-fold increase in incidence rate of abnormal larva formation. In T. japonicus, exposure to TDCIPP (10 μg L−1) resulted in non-viable broods and a significant reduction in the number of eggs and number of nauplii. Conclusions Larval survival, larval growth, fecundity, and embryonic development were identified as the TDCIPP-affected ecological endpoints in the marine invertebrate C. onyx and T. japonicus. Implications From a management perspective, these results can help us assess the ecological risk posed by TDCIPP.

Embryonic development of eggs and stereological analysis of body of Neoechinorhynchus buttnerae (Golvan, 1956) (Eoacanthocephala: Neoechinorhynchidae).

The egg is one of the fundamental parts of the life cycle of Neoechinorhynchus buttnerae, and this stage involves the acanthor larva. It is also the infection phase for the intermediate host. Under normal conditions, the larva inside the egg can survive for months in the environment; however, information regarding this phase of life of the parasite is scarce. In addition, there is no quantitative information about the structural composition of the parasite's body from a histological point of view. Such information is essential in order to support decisions aimed at controlling infestations by these parasites in fish farming. This study aimed to present a detailed description of the stages of embryonic development of N. buttnerae eggs, as well as a stereological evaluation of the body of adult females of the parasite. Three phases of development characterized the eggs: cell division (with four stages), formation of the internal nuclear mass (with four stages) and formation of the acanthor larva (with five stages). The ovary comprised 26.61% of the volume of the animal and most of it contained eggs (21.28%), ovarian balls (3.88%) and empty spaces (1.45%). These results are of great importance and will support future studies that seek to interrupt the life cycle of this parasite.

Fenoxycarb Effects 7th instar Galleria mellonella Larvae by Triggering Extra Larval Stages

Insect growth regulators are specific chemicals with hormonal effects on insects and these types of chemicals target to reduce the nonspecific effects of pesticides on nature and living things. In this study, we investigated the effects of one of the insect growth regulators, fenoxycarb which mimics the juvenile hormone action, on the growth of a harmful lepidopteran species Galleria mellonella, and it’s some developmental parameters. For this purpose, fenoxycarb was applied on day 0 of 7th instar larvae of the greater wax moth, Galleria mellonella. The treatment with 100 ng fenoxycarb had no developmental effect on Galleria mellonella larvae. The treatment with relatively high doses of fenoxycarb on day 0 induced the supernumerary larvae formation of 99% and larvae which molted extra larval instar formed healthy pupae in the ratio of 98-99%. Consequently, the effects of fenoxycarb on Galleria mellonella larvae occurred in a dose-dependent manner. Although fenoxycarb is a potent insect growth regulator, late Galleria mellonella larvae are not susceptible to this chemical, unlike some other Lepidopter insect species.

Early embryogenesis and organogenesis in the annelid Owenia fusiformis

BackgroundAnnelids are a diverse group of segmented worms within Spiralia, whose embryos exhibit spiral cleavage and a variety of larval forms. While most modern embryological studies focus on species with unequal spiral cleavage nested in Pleistoannelida (Sedentaria + Errantia), a few recent studies looked into Owenia fusiformis, a member of the sister group to all remaining annelids and thus a key lineage to understand annelid and spiralian evolution and development. However, the timing of early cleavage and detailed morphogenetic events leading to the formation of the idiosyncratic mitraria larva of O. fusiformis remain largely unexplored.ResultsOwenia fusiformis undergoes equal spiral cleavage where the first quartet of animal micromeres are slightly larger than the vegetal macromeres. Cleavage results in a coeloblastula approximately 5 h post-fertilization (hpf) at 19 °C. Gastrulation occurs via invagination and completes 4 h later, with putative mesodermal precursors and the chaetoblasts appearing 10 hpf at the dorso-posterior side. Soon after, at 11 hpf, the apical tuft emerges, followed by the first neurons (as revealed by the expression of elav1 and synaptotagmin-1) in the apical organ and the prototroch by 13 hpf. Muscles connecting the chaetal sac to various larval tissues develop around 18 hpf and by the time the mitraria is fully formed at 22 hpf, there are FMRFamide+ neurons in the apical organ and prototroch, the latter forming a prototrochal ring. As the mitraria feeds, it grows in size and the prototroch expands through active proliferation. The larva becomes competent after ~ 3 weeks post-fertilization at 15 °C, when a conspicuous juvenile rudiment has formed ventrally.ConclusionsOwenia fusiformis embryogenesis is similar to that of other equal spiral cleaving annelids, supporting that equal cleavage is associated with the formation of a coeloblastula, gastrulation via invagination, and a feeding trochophore-like larva in Annelida. The nervous system of the mitraria larva forms earlier and is more elaborated than previously recognized and develops from anterior to posterior, which is likely an ancestral condition to Annelida. Altogether, our study identifies the major developmental events during O. fusiformis ontogeny, defining a conceptual framework for future investigations.

Antibacterial activity of pimaric acid against the causative agent of American foulbrood, Paenibacillus larvae

The number of bees has decreased drastically partly due to bacterial pathogens like Paenibacillus larvae that cause American foulbrood disease. The recent emergence of pathogenic resistant strains makes it more difficult to, successfully, treat infections. Research on alternative antibacterial agents from naturally occurring plants that also have low toxicity levels is critical to address the issue of Paenibacillus larvae in bee colonies. Five compounds were screened with a minimal inhibitory concentration (MIC) test in order to identify a compound with effective antibacterial activity against Paenibacillus larvae. Of the tested compounds, pimaric acid showed the best antibacterial activity with a MIC value of 6.25 µg/ml after 48 hours of incubation on MYPGP media. An agar diffusion test also confirmed the anti- Paenibacillus larvae activity of pimaric acid with an inhibitory zone of 10 to 14 mm. Crystal violet assay results suggested that pimaric acid disrupted the plasma membrane of Paenibacillus larvae, causing the leakage of material with an optical density of 260-nm and 280-nm, which confirmed that the compound induces the rupture of this microorganism. Pimaric acid inhibited the formation of a Paenibacillus larvae biofilm in a dose-dependent manner. An additive effect of pimaric acid with tetracycline and terramycin was shown through a checkerboard assay with a fractional inhibitory concentration (FIC) index value of 0.75. Finally, an MTT assay on insect cells of Trichoplusia ni and normal human skin cells from the HaCaT cell line, showed that pimaric acid is safe for both insect cell and human skin cells at the dosage required to treat Paenibacillus larvae.