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Acta Tropica Aug 2024In Mexico, more than 30 species of triatomines, vectors of Trypanosoma cruzi, the etiological agent of Chagas disease, have been collected. Among them, Triatoma...
Behavioral and biological parameters of six populations of Triatoma pallidipennis (Heteroptera: Reduviidae) from areas with high and low prevalence rates of Trypanosoma cruzi human infection.
In Mexico, more than 30 species of triatomines, vectors of Trypanosoma cruzi, the etiological agent of Chagas disease, have been collected. Among them, Triatoma pallidipennis stands out for its wide geographical distribution, high infection rates and domiciliation. Local populations of triatomines have shown notable biological and behavioral differences, influencing their vectorial capacity. Six behaviors of epidemiological importance, namely, egg-to-adult development time, median number of blood meals to molt to the next instar, instar mortality rates, aggressiveness (delay in initiating a meal), feeding time and defecation delay, were evaluated in this study for six populations of T. pallidipennis. Those populations from central, western and southern Mexico were arranged by pairs with a combination of high (HP) and medium (MP) of Trypanosoma cruzi human infection and most (MFC) and low (CLF) collection frequencies: HP/MFC, HP/CLF, and MP/MFC. The development time was longer in HP/CLF populations (> 220 days). The median number of blood meals to molt was similar (7-9) among five of the six populations. Mortality rates were greater (> 40 %) in HP/CLF and one MP/MFC populations. All studied populations were aggressive but exhibited slight differences among them. The feeding times were similar (≥ 10 min) for all studied populations within instars, increasing as instars progressed. An irregular pattern was observed in defecation behaviors, with marked differences even between the two populations from the same pair. High percentages of young (57.3-87.9 %), and old (62.4-89.8 %) nymphs, of female (61.1-97.3 %) and male (65.7-93.1 %) of all the studied populations defecated quickly (while eating, immediately after finishing feeding or < 1 min postfeeding). Our results indicate that the HP/MFC populations are potentially highly effective vectors for transmitting T. cruzi infections, while HP/CLF populations are potentially less effective vectors T. cruzi infections.
Topics: Animals; Triatoma; Chagas Disease; Mexico; Female; Trypanosoma cruzi; Insect Vectors; Humans; Male; Feeding Behavior; Prevalence; Defecation
PubMed: 38821148
DOI: 10.1016/j.actatropica.2024.107259 -
Zoological Science Jun 2024Species in the anthurid isopod genus have specific, dorsal dark pigmentation patterning on the body. Though species have traditionally been distinguished mainly by...
Species in the anthurid isopod genus have specific, dorsal dark pigmentation patterning on the body. Though species have traditionally been distinguished mainly by differences in the dorsal pigmentation pattern in females, the stability of the pigmentation pattern within species had not been investigated, and information was lacking on ontogenetic variation in the pattern. Our study showed the following for . (1) Mancae begin to show dorsal pigmentation in the marsupium roughly 9 days before their release. (2) The pigmentation pattern in the first-instar mancae (first free-living stage) differs from that in later instars. (3) The pigmentation pattern in females is discrete and stable from putative second-instar mancae through females lacking oostegites, and distorted but recognizable in ovigerious females. (4) The pattern in males is different from and less discrete than that in females; it remains similar through the molt from subadult to adult male but changes markedly with age, leading to heavy pigmentation of the body. (5) The pigmentation pattern in mancae and females remains stable and observable after storage in ethanol for at least 13.7 months. Our results suggest that comparisons of pigmentation pattern across species in taxonomy should be restricted to females in the post-manca or later stages.
Topics: Animals; Isopoda; Pigmentation; Female; Male
PubMed: 38809871
DOI: 10.2108/zs230122 -
Veterinary World Apr 2024is an obligate intraerythrocytic rickettsial parasite that infects cattle in tropical and subtropical regions. There is no evidence that inoculation can be used to...
BACKGROUND AND AIM
is an obligate intraerythrocytic rickettsial parasite that infects cattle in tropical and subtropical regions. There is no evidence that inoculation can be used to culture in rabbits. This study aimed to determine the molting of s larvae, nymphs, and adults on rabbits as well as nymphs and adults of on calves with or without . Transstadial, horizontal, and transovarial transmissions of in reared on rabbits and calves were evaluated.
MATERIALS AND METHODS
Engorged female ticks were collected from field samples of -infected and non-infected cattle. We divided the eight rabbits into two groups: A and B. Group A rabbits were infected with through parenteral inoculation, whereas Group B rabbits were kept as a control. The "clean rabbits" in Group B were observed for tick rearing without . Polymerase chain reaction was used to screen in rabbits and stages of tick. The complete life cycle of with or without was observed on rabbits.
RESULTS
A 6.5-day longer life cycle was observed in ticks harboring than in ticks without . To observe transstadial transmission, transstadial, horizontal, and transovarial transmissions of in ticks were experimentally observed in one clean calf fed separately with infected nymphs and female adult ticks.
CONCLUSION
We experimentally observed transovarian, transstadial, and transovarial transmission of in ticks as a biological vector reared on calves and rabbits. We used rabbits as a model animal for rearing ticks and culture of .
PubMed: 38798298
DOI: 10.14202/vetworld.2024.903-910 -
Genetics May 2024The major loci for the large primary ribosomal RNA (rRNA) genes (35S rRNAs) exist as hundreds to thousands of tandem repeats in all organisms and dozens to hundreds in...
The major loci for the large primary ribosomal RNA (rRNA) genes (35S rRNAs) exist as hundreds to thousands of tandem repeats in all organisms and dozens to hundreds in Drosophila. The highly repetitive nature of the ribosomal DNA (rDNA) makes it intrinsically unstable, and many conditions arise from the reduction in or magnification of copy number, but the conditions under which it does so remain unknown. By targeted DNA damage to the rDNA of the Y chromosome, we created and investigated a series of rDNA alleles. We found that complete loss of rDNA leads to lethality after the completion of embryogenesis, blocking larval molting and metamorphosis. We find that the resident retrotransposons-R1 and R2-are regulated by active rDNA such that reduction in copy number derepresses these elements. Their expression is highest during the early first instar, when loss of rDNA is lethal. Regulation of R1 and R2 may be related to their structural arrangement within the rDNA, as we find they are clustered in the flanks of the nucleolus organizing region (NOR; the cytological appearance of the rDNA). We assessed the complex nucleolar dominance relationship between X- and Y-linked rDNA using a histone H3.3-GFP reporter construct and incorporation at the NOR and found that dominance is controlled by rDNA copy number as at high multiplicity the Y-linked array is dominant, but at low multiplicity the X-linked array becomes derepressed. Finally, we found that multiple conditions that disrupt nucleolar dominance lead to increased rDNA magnification, suggesting that the phenomena of dominance and magnification are related, and a single mechanism may underlie and unify these two longstanding observations in Drosophila.
PubMed: 38797870
DOI: 10.1093/genetics/iyae063 -
Molecules (Basel, Switzerland) May 2024L-asparaginases are used in the treatment of acute lymphoblastic leukemia. The aim of this work was to compare the antiproliferative potential and proapoptotic...
L-asparaginases are used in the treatment of acute lymphoblastic leukemia. The aim of this work was to compare the antiproliferative potential and proapoptotic properties of novel L-asparaginases from different structural classes, viz. EcAIII and KpAIII (class 2), as well as ReAIV and ReAV (class 3). The EcAII (class 1) enzyme served as a reference. The proapoptotic and antiproliferative effects were tested using four human leukemia cell models: MOLT-4, RAJI, THP-1, and HL-60. The antiproliferative assay with the MOLT-4 cell line indicated the inhibitory properties of all tested L-asparaginases. The results from the THP-1 cell models showed a similar antiproliferative effect in the presence of EcAII, EcAIII, and KpAIII. In the case of HL-60 cells, the inhibition of proliferation was observed in the presence of EcAII and KpAIII, whereas the proliferation of RAJI cells was inhibited only by EcAII. The results of the proapoptotic assays showed individual effects of the enzymes toward specific cell lines, suggesting a selective (time-dependent and dose-dependent) action of the tested L-asparaginases. We have, thus, demonstrated that novel L-asparaginases, with a lower substrate affinity than EcAII, also exhibit significant antileukemic properties in vitro, which makes them interesting new drug candidates for the treatment of hematological malignancies. For all enzymes, the kinetic parameters (K and k) and thermal stability (T) were determined. Structural and catalytic properties of L-asparaginases from different classes are also summarized.
Topics: Humans; Asparaginase; Antineoplastic Agents; Apoptosis; Cell Proliferation; Cell Line, Tumor; Substrate Specificity; HL-60 Cells; Leukemia
PubMed: 38792133
DOI: 10.3390/molecules29102272 -
Scientific Reports May 2024Behaviors can vary throughout an animal's life and this variation can often be explained by changes associated with learning and/or maturing. Currently, there is little...
Behaviors can vary throughout an animal's life and this variation can often be explained by changes associated with learning and/or maturing. Currently, there is little consensus regarding how these processes interact to affect behaviors. Here we proposed a heuristic approach to disentangle the effects of learning and maturation on behavior and applied it to the predatory behaviors of Physocyclus globosus spiderlings. We varied the degree of prey difficulty and familiarity spiderlings received along the first instar and across the molt to the second instar and quantified the time spiderlings spent wrapping prey, as a proxy for prey capture efficiency. We found no overall evidence for learning or maturation. Changes in efficiency were mainly due to the switch from difficult to easy prey, or vice versa. However, there was one treatment where spiderlings improved in efficiency before and after the molt, without a switch in prey type. This provides some indication that difficult prey may offer more opportunity for learning or maturation to impact behavior. Although we found little effect of learning or maturation on prey capture efficiency, we suggest that our heuristic approach is effective and could be useful in investigating these processes in other behaviors and other animals.
Topics: Animals; Spiders; Predatory Behavior; Learning; Heuristics
PubMed: 38778018
DOI: 10.1038/s41598-024-61252-7 -
G3 (Bethesda, Md.) May 2024Body size is a fundamental trait that drives multiple evolutionary and ecological patterns. Caenorhabditis inopinata is a fig-associated nematode that is exceptionally...
Body size is a fundamental trait that drives multiple evolutionary and ecological patterns. Caenorhabditis inopinata is a fig-associated nematode that is exceptionally large relative to other members of the genus, including C. elegans. We previously showed that C. inopinata is large primarily due to postembryonic cell size expansion that occurs during the larval-to-adult transition. Here, we describe gene expression patterns in C. elegans and C. inopinata throughout this developmental period to understand the transcriptional basis of body size change. We performed RNA-seq in both species across the L3, L4, and adult stages. Most genes are differentially expressed across all developmental stages, consistent with C. inopinata's divergent ecology and morphology. We also used a model comparison approach to identify orthologs with divergent dynamics across this developmental period between the two species. This included genes connected to neurons, behavior, stress response, developmental timing, and small RNA/chromatin regulation. Multiple hypodermal collagens were also observed to harbor divergent developmental dynamics across this period, and genes important for molting and body morphology were also detected. Genes associated with TGF-β signaling revealed idiosyncratic and unexpected transcriptional patterns given their role in body size regulation in C. elegans. Widespread transcriptional divergence between these species is unexpected and may be a signature of the ecological and morphological divergence of C. inopinata. Alternatively, transcriptional turnover may be the rule in the Caenorhabditis genus, indicative of widespread developmental system drift among species. This work lays the foundation for future functional genetic studies interrogating the bases of body size evolution in this group.
PubMed: 38775657
DOI: 10.1093/g3journal/jkae110 -
BioRxiv : the Preprint Server For... May 2024Apical extracellular matrices (aECMs) are associated with all epithelia and form a protective layer against biotic and abiotic threats in the environment. Despite their...
Apical extracellular matrices (aECMs) are associated with all epithelia and form a protective layer against biotic and abiotic threats in the environment. Despite their importance, we lack a deep understanding of their structure and dynamics in development and disease. molting offers a powerful entry point to understanding developmentally programmed aECM remodeling. A transient matrix is formed in embryos and at the end of each larval stage, presumably to pattern the new cuticle. Focusing on targets of NHR-23, a key transcription factor which drives molting, we identified the Kunitz family protease inhibitor gene as an NHR-23 target. We identified NHR-23-binding sites that are necessary and sufficient for epithelial expression. is necessary to pattern every layer of the adult cuticle, suggesting a broad patterning role prior to the formation of the mature cuticle. MLT-11::mNeonGreen::3xFLAG transiently localized to the aECM in the cuticle and embryo. It was also detected in lining openings to the exterior (vulva, rectum, mouth). Reduction of function disrupted the barrier function of the cuticle. Tissue-specific RNAi suggested activity is primarily necessary in seam cells and we observed alae and seam cell fusion defects upon inactivation. Predicted null mutations caused fully penetrant embryonic lethality and elongation defects suggesting also plays an important role in patterning the embryonic sheath. Finally, we found that inactivation suppressed the blistered cuticle phenotype of mutants of mutants, a subtilisin protease gene but did not affect BLI-4::sfGFP expression. These data could suggest that MLT-11 may be necessary to assure proper levels of BLI-4 activity.
PubMed: 38766248
DOI: 10.1101/2024.05.12.593762 -
BioRxiv : the Preprint Server For... May 2024The mammalian PAS-domain protein PERIOD (PER) and its orthologue LIN-42 have been proposed to constitute an evolutionary link between two distinct, circadian and...
The mammalian PAS-domain protein PERIOD (PER) and its orthologue LIN-42 have been proposed to constitute an evolutionary link between two distinct, circadian and developmental, timing systems. However, while the function of PER in animal circadian rhythms is well understood molecularly and mechanistically, this is not true for the function of LIN-42 in timing rhythmic development. Here, using targeted deletions, we find that the LIN-42 PAS domains are dispensable for the protein's function in timing molts. Instead, we observe arrhythmic molts upon deletion of a distinct sequence element, conserved with PER. We show that this element mediates stable binding to KIN-20, the CK1δ/ε orthologue. We demonstrate that CK1δ phosphorylates LIN-42 and define two conserved helical motifs, CK1δ-binding domain A (CK1BD-A) and CK1BD-B, that have distinct roles in controlling CK1δ-binding and kinase activity . KIN-20 and the LIN-42 CK1BD are required for proper molting timing . These interactions mirror the central role of a stable circadian PER-CK1 complex in setting a robust ~24-hour period. Hence, our results establish LIN-42/PER - KIN-20/CK1δ/ε as a functionally conserved signaling module of two distinct chronobiological systems.
PubMed: 38766223
DOI: 10.1101/2024.05.09.593322 -
International Journal of Biological... Jun 2024Nuclear receptors (NRs) are ligand-regulated transcription factors that are important for the normal growth and development of insects. However, systematic function...
Nuclear receptors (NRs) are ligand-regulated transcription factors that are important for the normal growth and development of insects. However, systematic function analysis of NRs in the molting process of Lasioderma serricorne has not been reported. In this study, we identified and characterized 16 NR genes from L. serricorne. Spatiotemporal expression analysis revealed that six NRs were mainly expressed in 3-d-old 4th-instar larvae; five NRs were primarily expressed in 5-d-old adults and four NRs were predominately expressed in prepupae. All the NRs were highly expressed in epidermis, fat body and foregut. RNA interference (RNAi) experiments revealed that knockdown of 15 NRs disrupted the larva-pupa-adult transitions and caused 64.44-100 % mortality. Hematoxylin-eosin staining showed that depletion of 12 NRs prevented the formation of new cuticle and disrupted apolysis of old cuticle. Silencing of LsHR96, LsSVP and LsE78 led to newly formed cuticle that was thinner than the controls. The 20E titer and chitin content significantly decreased by 17.67-95.12 % after 15 NR dsRNA injection and the gene expression levels of 20E synthesis genes and chitin metabolism genes were significantly reduced. These results demonstrated that 15 NR genes are essential for normal molting and metamorphosis of L. serricorne by regulating 20E synthesis and chitin metabolism.
Topics: Animals; Molting; Metamorphosis, Biological; Coleoptera; Receptors, Cytoplasmic and Nuclear; Gene Expression Regulation, Developmental; Larva; Chitin; RNA Interference; Insect Proteins; Phylogeny; Ecdysterone
PubMed: 38763254
DOI: 10.1016/j.ijbiomac.2024.132459