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Poultry Science Aug 2006A tissue culture procedure was utilized to compare tissue cell invasion by Salmonella enteritidis from molted and full feed hens. Three identical trials were performed...
A tissue culture procedure was utilized to compare tissue cell invasion by Salmonella enteritidis from molted and full feed hens. Three identical trials were performed in which 80-wk-old active laying hens were divided into 2 groups of 6 birds each. The molted hen group was subjected to a 14-d feed withdrawal, and the full-fed hen group was administered a standard layer ration. After feed treatment, crop, ileum, cecum, and ovary (small and large yellow follicles removed) were collected, rinsed in PBS, and placed into 50 mL of RPMI medium. The ends of intestine and crop tissues were tied to allow attachment of Salmonella only to the lumen surface. The RPMI medium containing 10(7) to 10(8) cfu of novobiocin and nalidixic acid-resistant phage type 13 Salmonella enteritidis was injected into the lumen of the intestine and crop tissues. Additionally, ovaries were incubated in 50 mL of RPMI medium containing 10(6) to 10(7) cfu of the Salmonella enteritidis. Tissues were incubated with Salmonella at 37 degrees C for 2 h, after which tissues were placed in 50 mL of fresh RPMI medium containing 500 microg/mL of gentamicin and incubated for 5 h at 37 degrees C to remove any Salmonella that had not penetrated tissues. Tissues were rinsed, stomached in 10 mL of PBS, serially diluted, and plated onto brilliant green agar containing novobiocin and nalidixic acid for Salmonella enumeration. Salmonella invasion of ovaries was reduced in tissues from molted hens in trials 1 and 2 as compared with full-fed controls (> 1.2 log reduction) but not in trial 3. Salmonella invasion of ceca from molted hens was numerically increased in trials 1 and 2 and significantly increased in trial 3 as compared with controls (> 0.8 log increase). No significant differences in Salmonella invasion were detected for crops and ileum. These data suggest that molting may affect invasion of tissues by Salmonella enteritidis.
Topics: Animals; Bacterial Adhesion; Chickens; Colony Count, Microbial; Crop, Avian; Female; Food Deprivation; Intestines; Molting; Organ Specificity; Ovary; Poultry Diseases; Random Allocation; Salmonella Infections, Animal; Salmonella enteritidis
PubMed: 16903461
DOI: 10.1093/ps/85.8.1333 -
Physiological and Biochemical Zoology :... 2010Physiological processes are regulated by a diverse array of neuropeptides that coordinate organ systems. The neuropeptides, many of which act through G protein-coupled...
Physiological processes are regulated by a diverse array of neuropeptides that coordinate organ systems. The neuropeptides, many of which act through G protein-coupled receptors, affect the levels of cyclic nucleotides (cAMP and cGMP) and Ca(2+) in target tissues. In this perspective, their roles in molting, osmoregulation, metabolite utilization, and cardiovascular function are highlighted. In decapod crustaceans, inhibitory neuropeptides (molt-inhibiting hormone and crustacean hyperglycemic hormone) suppress the molting gland through cAMP- and cGMP-mediated signaling. In insects, the complex movements during ecdysis are controlled by ecdysis-triggering hormone and a cascade of downstream neuropeptides. Adipokinetic/hypertrehalosemic/hyperprolinemic hormones mobilize energy stores in response to increased locomotory activity. Crustacean cardioacceleratory (cardioactive) peptide, proctolin, and FMRFamide-related peptides act on the heart, accessory pulsatile organs, and excurrent ostia to control hemolymph distribution to tissues. The osmoregulatory challenge of blood gorging in Rhodnius prolixus requires the coordinated release of serotonin and diuretic and antidiuretic hormones acting on the midgut and Malpighian tubules. These studies illustrate how multiple neuropeptides allow for flexibility in response to physiological challenges.
Topics: Animals; Calcium; Cardiovascular Physiological Phenomena; Crustacea; Hemodynamics; Hormones; Insecta; Molting; Neuropeptides; Nucleotides, Cyclic; Signal Transduction; Water-Electrolyte Balance
PubMed: 20550437
DOI: 10.1086/648470 -
Developmental Biology Mar 2022Molting is a widespread feature in the development of many invertebrates, including nematodes and arthropods. In Caenorhabditis elegans, the highly conserved protein...
Molting is a widespread feature in the development of many invertebrates, including nematodes and arthropods. In Caenorhabditis elegans, the highly conserved protein kinases NEKL-2/NEK8/9 and NEKL-3/NEK6/7 (NEKLs) promote molting through their involvement in the uptake and intracellular trafficking of epidermal cargos. We found that the relative requirements for NEKL-2 and NEKL-3 differed at different life-cycle stages and under different environmental conditions. Most notably, the transition from the second to the third larval stage (L2→L3 molt) required a higher level of NEKL function than during several other life stages or when animals had experienced starvation at the L1 stage. Specifically, larvae that entered the pre-dauer L2d stage could escape molting defects when transiting to the (non-dauer) L3 stage. Consistent with this, mutations that promote entry into L2d suppressed nekl-associated molting defects, whereas mutations that inhibit L2d entry reduced starvation-mediated suppression. We further showed that loss or reduction of NEKL functions led to defects in the transcription of cyclically expressed molting genes, many of which are under the control of systemic steroid hormone regulation. Moreover, the timing and severity of these transcriptional defects correlated closely with the strength of nekl alleles and with their stage of arrest. Interestingly, transit through L2d rescued nekl-associated expression defects in suppressed worms, providing an example of how life-cycle decisions can impact subsequent developmental events. Given that NEKLs are implicated in the uptake of sterols by the epidermis, we propose that loss of NEKLs leads to a physiological reduction in steroid-hormone signaling and consequent defects in the transcription of genes required for molting.
Topics: Alleles; Animals; Animals, Genetically Modified; CRISPR-Cas Systems; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Endocytosis; Epidermis; Forkhead Transcription Factors; Gene Expression Regulation, Developmental; Larva; Life Cycle Stages; Loss of Function Mutation; Molting; NIMA-Related Kinases; Signal Transduction; Starvation; Sterols; Up-Regulation
PubMed: 35038442
DOI: 10.1016/j.ydbio.2022.01.001 -
Physiological and Biochemical Zoology :... 2021AbstractHarbor seals () live in cold temperate or polar seas and molt annually, renewing their fur over a period of approximately 4 wk. Epidermal processes at this time...
AbstractHarbor seals () live in cold temperate or polar seas and molt annually, renewing their fur over a period of approximately 4 wk. Epidermal processes at this time require a warm skin; therefore, to avoid an excessive energy cost at sea during the molt, harbor seals and many other pinnipeds increase the proportion of time they are hauled out on land. We predicted that metabolic rate during haul-out would be greater during the molt to sustain an elevated skin temperature in order to optimize skin and hair growth. To examine this, we measured post-haul-out oxygen consumption () in captive harbor seals during molt and postmolt periods. We recorded greater of seals while they were molting than when the molt was complete. Post-haul-out increased faster and reached a greater maximum during the first 40 min. Thereafter, decreased but still remained greater, suggesting that while metabolic rate was relatively high throughout haul-outs, it was most pronounced in the first 40 min. Air temperature, estimated heat increment of feeding, and mass also explained 15.5% of variation over 180 min after haul-out, suggesting that the environment, feeding state, and body size influenced the metabolic rate of individual animals. These results show that molting seals have greater metabolic rates when hauled out, especially during the early stages of the haul-out period. As a consequence, human disturbance that changes the haul-out behavior of molting seals will increase their energy costs and potentially extend the duration of the molt.
Topics: Animals; Energy Metabolism; Feeding Behavior; Male; Molting; Oxygen Consumption; Phoca; Seasons
PubMed: 33710938
DOI: 10.1086/713958 -
Environmental Science & Technology Nov 2020The densely populated North Sea region encompasses catchments of rivers such as Scheldt and Meuse. Herein, agricultural, industrial, and household chemicals are emitted,...
The densely populated North Sea region encompasses catchments of rivers such as Scheldt and Meuse. Herein, agricultural, industrial, and household chemicals are emitted, transported by water, and deposited in sediments, posing ecological risks. Though sediment monitoring is often costly and time-intensive, modeling its toxicity to biota has received little attention. Due to high complexity of interacting variables that induce overall toxicity, monitoring data only sporadically validates current models. Via a range of concepts, we related bio-physicochemical constituents of sediment in Flanders to results from toxicity bioassays performed on the ostracod . Depending on the water body, we explain up to 90% of the variance in growth. Though variable across Flanders' main water bodies, organotin cations and ammonia dominate the observed toxicity according to toxic unit (TU) assessments. Approximately 10% relates to testing conditions/setups, species variabilities, incoherently documented pollutant concentrations, and/or bio-physicochemical sediment properties. We elucidated the influence of organotin cations and ammonia relative to other metal(oxides) and biocides. Surprisingly, the tributylin cation appeared ∼1000 times more toxic to as compared to "single-substance" bioassays for similar species. We inferred indirect mixture effects between organotin, ammonia, and phosphate. Via chemical speciation calculations, we observed strong physicochemical and biological interactions between phosphate and organotin cations. These interactions enhance bioconcentration and explain the elevated toxicity of organotin cations. Our study aids water managers and policy makers to interpret monitoring data on a mechanistic basis. As sampled sediments differ, future modeling requires more emphasis on characterizing and parametrizing the interactions between bioassay constituents. We envision that this will aid in bridging the gap between testing in the laboratory and field observations.
Topics: Animals; Bioaccumulation; Cations; Crustacea; Environmental Monitoring; Geologic Sediments; Molting; North Sea; Toxicity Tests; Water Pollutants, Chemical
PubMed: 33135409
DOI: 10.1021/acs.est.0c02855 -
Frontiers in Bioscience (Elite Edition) Jan 2012Crustaceans have a rigid exoskeleton, which is made of a layered cuticle, covering the soft body parts for protection from conspecific competitors and/or interspecific... (Review)
Review
Crustaceans have a rigid exoskeleton, which is made of a layered cuticle, covering the soft body parts for protection from conspecific competitors and/or interspecific predators. Calcium carbonate adds rigidity to the crustacean cuticle, which consequently means that growth only occur at each molt. The current study presents a review of existing literature on crustacean exoskeleton cuticle physiology and biochemistry in relation to the molting process with special reference to calcification. As a result, research matter where knowledge remains limited has been identified during the molting process, including 1) whether the same or different epithelial cells are responsible for the decomposition and/or reconstruction of chitin and proteins, 2) how calcium carbonate levels are regulated at the cellular level during transfer between the cuticle and body organs, and 3) what factors maintain the amorphous state of calcium carbonate following deposition in the exoskeleton and temporary storage organs. The identification of these areas of focus provides a basis on which targeted future research may be developed, and potentially applied to other invertebrate or even vertebrate processes.
Topics: Animals; Calcium Carbonate; Chitin; Crustacea; Molecular Structure; Molting
PubMed: 22201907
DOI: 10.2741/e412 -
Developmental Biology Sep 2016In contrast with Drosophila melanogaster, practically nothing is known about the involvement of the TGF-β signaling pathway in the metamorphosis of hemimetabolan...
In contrast with Drosophila melanogaster, practically nothing is known about the involvement of the TGF-β signaling pathway in the metamorphosis of hemimetabolan insects. To partially fill this gap, we have studied the role of Smad factors in the metamorphosis of the German cockroach, Blattella germanica. In D. melanogaster, Mad is the canonical R-Smad of the BMP branch of the TGF-β signaling pathway, Smox is the canonical R-Smad of the TGF-β/Activin branch and Medea participates in both branches. In insects, metamorphosis is regulated by the MEKRE93 pathway, which starts with juvenile hormone (JH), whose signal is transduced by Methoprene-tolerant (Met), which stimulates the expression of Krüppel homolog 1 (Kr-h1) that acts to repress E93, the metamorphosis trigger. In B. germanica, metamorphosis is determined at the beginning of the sixth (final) nymphal instar (N6), when JH production ceases, the expression of Kr-h1 declines, and the transcription of E93 begins to increase. The RNAi of Mad, Smox and Medea in N6 of B. germanica reveals that the BMP branch of the TGF-β signaling pathway regulates adult ecdysis and wing extension, mainly through regulating the expression of bursicon, whereas the TGF-β/Activin branch contributes to increasing E93 and decreasing Kr-h1 at the beginning of N6, crucial for triggering adult morphogenesis, as well as to regulating the imaginal molt timing.
Topics: Activins; Animals; Bone Morphogenetic Proteins; Cockroaches; DNA-Binding Proteins; Drosophila Proteins; Drosophila melanogaster; Gene Expression Regulation, Developmental; Juvenile Hormones; Kruppel-Like Transcription Factors; Metamorphosis, Biological; Molting; RNA Interference; RNA, Small Interfering; Signal Transduction; Smad Proteins; Smad Proteins, Receptor-Regulated; Smad4 Protein; Transcription Factors; Transforming Growth Factor beta
PubMed: 27452629
DOI: 10.1016/j.ydbio.2016.07.006 -
Current Biology : CB Feb 2021Animals with exoskeletons molt for further growth. In insects, the number of larval (or nymphal) molts varies inter- and intra-specifically, and it is widely accepted...
Animals with exoskeletons molt for further growth. In insects, the number of larval (or nymphal) molts varies inter- and intra-specifically, and it is widely accepted that the variation in the number of larval molts is an adaptive response to diverse environmental conditions. However, the molecular mechanism that underlies the variety and plasticity in the number of larval molts is largely unknown. In the silkworm, Bombyx mori, there are strains that molt three, four, or five times, and these numbers are determined by allelic variation at a single autosomal locus, Moltinism (M). Here, we demonstrate that the Hox gene Sex combs reduced (Scr) is responsible for the phenotypes of the M locus. Scr is selectively expressed in the larval prothoracic gland (PG), an endocrine organ that produces molting hormones.Scr represses the biosynthesis of molting hormones in the PG, thereby regulating the incremental increase in body size during each larval instar. Our experiments consistently suggest that the differential expression levels of Scr among the three M alleles result in different growth ratios that ultimately lead to the different number of larval molts. Although the role of Hox genes in conferring segmental identity along the body axis and in molding segment-specific structure later in development has been well established, the present study identifies an unexpected role of Hox gene in hormone biosynthesis. This new role means that, in addition to shaping segment-specific morphology, Hox genes also drive the evolution of life history traits by regulating animal physiology.
Topics: Animals; Bombyx; Ecdysone; Larva; Molting; Phenotype
PubMed: 33308417
DOI: 10.1016/j.cub.2020.11.017 -
Current Biology : CB Jan 2021Ecdysis or molting evolved ∼535 mya in Ecdysozoa, the most diverse and species-rich animal superphylum. A cascade of ecdysis-related neuropeptides (ERNs) controls the...
Ecdysis or molting evolved ∼535 mya in Ecdysozoa, the most diverse and species-rich animal superphylum. A cascade of ecdysis-related neuropeptides (ERNs) controls the innate behavioral programs required for cuticle shedding in some ecdysozoan lineages (e.g., arthropods) but is lacking in others (e.g., nematodes). We recently reported on the surprisingly ancient bilaterian origin of key ERNs, such as eclosion hormone (EH), crustacean cardioactive neuropeptide (CCAP), myoinhibitory peptide (MIP), bursicon alpha (Bursα), and bursicon beta (Bursβ). Thus, ERNs far predate the emergence of ecdysis, but the question as to their ancestral functions remains unresolved. Here, we compare the ERN toolkits and temporal expression profiles of six ecdysozoans (tardigrades, crustaceans, and insects), eight lophotrochozoans (planarians, annelids, and mollusks), and five deuterostomes (crinoids, sea urchins, and hemichordates). Our results show that the major, coordinated upregulation of ERNs always coincides with a transition between key life history stages, such as hatching in direct developers and metamorphosis in indirect developers. This implies that ERNs already played an ancestral role in the switch from embryonic or larval ontogeny to juvenile maturation in the last common ancestor of Nephrozoa. Consequently, the transcriptional signature of invertebrate life cycle transitions presented here was already in place in the Precambrian and was only secondarily co-opted into regulating the molting process at the dawn of Ecdysozoa.
Topics: Animals; Biological Evolution; Life Cycle Stages; Molting; Neuropeptides
PubMed: 33125864
DOI: 10.1016/j.cub.2020.10.004 -
Poultry Science Jun 2008Two studies were conducted to evaluate the effects of melatonin on Salmonella Enteritidis infection in experimentally challenged laying hens subjected to a forced molt....
Two studies were conducted to evaluate the effects of melatonin on Salmonella Enteritidis infection in experimentally challenged laying hens subjected to a forced molt. Leghorn hens (>50 wk of age) were randomly assigned to rooms, acclimated to a 16L:8D regimen, and provided ad libitum access to a nonmedicated mash layer diet and water. Birds in one room were molted (8L:16D; complete feed withdrawal), whereas birds in the second room served as nonmolted controls (CONT). Within each room, birds were randomly assigned to melatonin treatment (MEL; 12 birds/treatment), dosed orally commencing the same day as feed withdrawal for 10 d: (experiment I: 0 or 5 mg of melatonin; experiment II: 0, 10, or 20 mg of melatonin). Three days following feed withdrawal, all birds were experimentally infected with Salmonella Enteritidis, and after 10 d of feed withdrawal, all birds were killed and necropsied. In experiment I, concentrations of Salmonella Enteritidis in the cecal contents and the number of Salmonella Enteritidis-positive tissues from the crop, ceca, liver, spleen, and ovary were higher (P < 0.0001) in the MOLT compared with the CONT treatments. No differences (P > 0.10) were observed in any of the parameters examined due to MEL treatment. For experiment II, cecal concentrations of Salmonella Enteritidis were generally higher in the MOLT compared with the CONT treatment and within molted birds, cecal concentrations were higher in the MEL treatment (P < 0.05). Melatonin treatment in molted birds increased (P < 0.05) the percentage of positive crops in the MOLT+20 MEL treatment (P < 0.05). Salmonella-positive cecal tissue was increased (P < 0.001) in MOLT compared with CONT birds and was also higher in MOLT+10 MEL and MOLT+20 MEL birds compared with the MOLT-only treatment. Results from the current research suggest that dosage with high levels of melatonin may exacerbate Salmonella Enteritidis infection in layers subjected to forced molt.
Topics: Animals; Cecum; Chickens; Crop, Avian; Female; Liver; Melatonin; Molting; Ovary; Oviposition; Salmonella enteritidis; Spleen
PubMed: 18492995
DOI: 10.3382/ps.2008-00016