Comb Growth Research Articles

Manipulating nest architecture reveals three-dimensional building strategies and colony resilience in honeybees.

Form follows function throughout the development of an organism. This principle should apply beyond the organism to the nests they build, but empirical studies are lacking. Honeybees provide a uniquely suited system to study nest form and function throughout development because we can image the three-dimensional structure repeatedly and non-destructively. Here, we tracked nest-wide comb growth in six colonies over 45 days (control colonies) and found that colonies have a stereotypical process of development that maintains a spheroid nest shape. To experimentally test if nest structure is important for colony function, we shuffled the nests of an additional six colonies, weekly rearranging the comb positions and orientations (shuffled colonies). Surprisingly, we found no differences between control and shuffled colonies in multiple colony performance metrics-worker population, comb area, hive weight and nest temperature. However, using predictive modelling to examine how workers allocate comb to expand their nests, we show that shuffled colonies compensate for these disruptions by accounting for the three-dimensional structure to reconnect their nest. This suggests that nest architecture is more flexible than previously thought, and that superorganisms have mechanisms to compensate for drastic architectural perturbations and maintain colony function.

The Effect of Natural Aromatase Blocker on the Growth Comb and Body Weight of Layer Chicken

The aim of this research is to evaluate the effect of Anadara granosa shell powder as a natural aromatase blocker (NAB) and zinc sulfate (ZnSO4) on the growth of the length comb, width comb, and body weight (BW) of layer chicken. This study used 45 DOC of layer’s chickens with 3 treatments and 15 replications, those are; control (T0), clamshell powder Anadara granosa as NAB 0.036 mg/40 g BW (T1), and ZnSO4 0.018 mg / 40 g BW (T2). This treatment was given for 35 days. The data on the growth of length comb, width comb, and BW are measured weekly. The data collected was analyzed using one-way ANOVA at the 95% confidence level with the assistance of SPSS. The results of statistical analysis of the length and width of the comb in the same column showed that T0 was not significantly different (p>0.05) from other treatments. The statistical analysis shows that the length and width of the layer’s chicken comb in the same row at T0, T1 and T2 were significantly different (p<0.05). The results of statistical analysis of the BW in the same column showed that T1 was significantly different (p<0.05) from other treatments. It can be concluded that additional NAB 0.036 mg/40 g BW can increase the body weight of male layer chicken after treatment of 35 days. The administration of NAB and ZnSO4 could not increase the growth of the length and width of layer chicken combs. The growth in length and width of layer chicken combs is very fast in the starter phase.

Study on CHADL as a candidate gene for comb growth traits in Partridge Shank roosters

The comb is an important secondary sexual characteristic and comb growth traits, such as size and color of the comb, are widely used as indicators in chicken breeding programs. However, the genetic basis for these traits remains mostly unknown. It was found that the chondroadherin-like (CHADL) gene was up-regulated in large combs and was located in reported comb growth quantitative trait loci. In this study, tissue-specific expressions, expression patterns in combs of different ages, and CHADL polymorphisms were analyzed to investigate the relationship between this gene and comb growth traits of Partridge Shank roosters. The results showed that CHADL was more highly expressed in combs than in 10 other tissues, and its expressions in combs tended to gradually increase from the 5-wk-old mark to the 26-wk-old mark. The single-nucleotide polymorphism rs316423539 in the CHADL gene was significantly associated with the comb area and height, whereas rs14822286 was highly correlated with the comb color. Moreover, H1H5, H1H6, and H3H6 were the most advantageous genotype combinations for comb growth traits. Our results might help understand the molecular mechanism of comb growth traits and improve these traits directly by marker assistant selections.

Identifying Signatures of Selection Related to Comb Development.

The aim of this study was to identify genes involved in comb development to provide insights into the molecular mechanism of chickens' comb formation. Fixation index (FST) and average number of base differences (π) of males with large and small combs were calculated based on whole-genome resequencing data. Chromosome regions with larger FST values and smaller π were considered candidate selection regions. Through further annotation of gene functions and pathways, we sought to screen possible selected genes associated with comb development. By screening whole genome resequencing data, FST and π were calculated using a 40 Kb sliding window strategy and eight regions were identified. Quantitative trait loci (QTL; FOX1 gene) related to comb length were found on chromosome 1. QTL (GLP1R, BTBD9, MIR6633, and MDGA1 genes) related to comb weight were found on chromosome 3. QTL (ALDH1A1, TMC1, and ANXA1 genes) associated with comb area were found on the Z chromosome. Nineteen genes, Wnt signaling pathway and neuroactive ligand-receptor interaction signaling pathway directly or indirectly related to comb growth and development were found through functional annotation and GO analysis. Among the selected genes LYN, GLP1R, FOX1, TBK1, STRAP, ST6GALNAC, and Wnt signaling pathways were related to immunity. MDGA1, BTBD9, MTSS1, SrGAPs, and neuroactive ligand receptor interaction signaling pathways related to neural function were screened. ALDH1A1, ANXAl, THBS, HIF-1α, and ACTN1 genes were related to heat dissipation. Among the selected genes FOX1, MDGAl, and ANXAl associated with immunity, neurological function, and heat dissipation function coincided with genes affecting the length, weight, and area of the comb. Comprehensive analysis suggested that comb development was due to multiple genes and signaling pathways.

Impact of Growing Media and Compound Fertilizer Rates on Growth and Flowering of Cocks Comb (Celosia argentea) Plants

The present study was conducted during consecutive seasons of 2016 and 2017 seasons in a private nursery belonging to Sakha Horticulture Research Station at Kafr El-Sheikh Governorate, Egypt. This study aimed mainly to investigate the effect of growing media including different mixture of peat moss and sand as 1:1, 2:1 and 1:2 v/v and NPK fertilizer at rates of 0 , 1.5, 3 and 4.5 g/pot and their interaction on growth, flowering and chemical composition of cocks comb (Celosia argentea) plants. The results revealed that growing media containing peat + sand (2:1) had significant positive effect on number of leaves and branches/plant, number of inflorescences and chlorophyll content (SPAD) as well as leaf chemical composition parameters (total carbohydrate, N, P and K %) in both seasons. Applying the complete fertilizer of NPK at 4.5g/pot was the best treatment for vegetative growth, flowering and chemical constituents of leaves. The maximum beneficial effect on the vegetative growth characteristics, number of inflorescences/plant and chlorophyll content (SPAD) and total carbohydrate as well as leaf, N, P and K % were obtained for plants grown in in peat + sand (2: 1 v/v) and fertilized by NPK (20: 20: 20) at rate of 4.5 g/pot. It can be recommended that to produce high inflorescences with a good quality of Celosia argentea plants for different purposes in the gardens by planting them in the mixture of peat moss + sand at 2: 1 v/v and fertilizing with complete fertilizer NPK (20:20:20) at rate 4.5g/pot four times stating after one month from transplant and then 2 weeks intervals.

Effect of seed priming on germination, emergence and seedling growth of cocks comb (Celosia cristata L.) under different salinity levels

Effect of seed priming on germination, emergence and seedling growth of cocks comb (Celosia cristata L.) under different salinity levels

Identification of molecular pathways and candidate genes associated with cocks\u2019 comb size trait by genome-wide transcriptome analysis

The comb of the male is an important secondary sexual characteristic. Although quantitative trait loci (QTLs) related to comb size have been identified, molecular mechanisms underlying this trait remain mostly unknown. In this study, RNA sequencing (RNA-seq) was employed to compare whole transcriptomic differences between two groups of Partridge Shank chickens that are divergent in comb sizes. A total of 563 differentially expressed genes (DEGs) were identified, including 277 up-regulated and 286 down-regulated DEGs. According to the animal QTL database, eight DEGs including BMP2 and CHADL matching the reported QTLs were associated with the comb size. Functional annotation analysis revealed that DEGs were involved in cell communication and calcium signaling. Protein-protein interaction network analysis showed that STK32A, PIK3R1, EDN1, HSPA5, and HSPA8 have an impact on comb growth. Moreover, potential alternative splicing events and single nucleotide polymorphisms were also identified. Our data provide a source for identifying genes and pathways with functions critical to comb size and accelerate studies involving molecular mechanisms of this sexual ornament.

Transgenic Chickens Overexpressing Aromatase Have High Estrogen Levels but Maintain a Predominantly Male Phenotype.

Estrogens play a key role in sexual differentiation of both the gonads and external traits in birds. The production of estrogen occurs via a well-characterized steroidogenic pathway, which is a multistep process involving several enzymes, including cytochrome P450 aromatase. In chicken embryos, the aromatase gene (CYP19A1) is expressed female-specifically from the time of gonadal sex differentiation. Ectopic overexpression of aromatase in male chicken embryos induces gonadal sex reversal, and male embryos treated with estradiol become feminized; however, this is not permanent. To test whether a continuous supply of estrogen in adult chickens could induce stable male to female sex reversal, 2 transgenic male chickens overexpressing aromatase were generated using the Tol2/transposase system. These birds had robust ectopic aromatase expression, which resulted in the production of high serum levels of estradiol. Transgenic males had female-like wattle and comb growth and feathering, but they retained male weights, displayed leg spurs, and developed testes. Despite the small sample size, this data strongly suggests that high levels of circulating estrogen are insufficient to maintain a female gonadal phenotype in adult birds. Previous observations of gynandromorph birds and embryos with mixed sex chimeric gonads have highlighted the role of cell autonomous sex identity in chickens. This might imply that in the study described here, direct genetic effects of the male chromosomes largely prevailed over the hormonal profile of the aromatase transgenic birds. This data therefore support the emerging view of at least partial cell autonomous sex development in birds. However, a larger study will confirm this intriguing observation.

Assessment of an ethanolic seed extract of Picralima nitida ([Stapf] Th. and H. Durand) on reproductive hormones and its safety for use.

Background:Picralima nitida seed extract (PNE) has aphrodisiac and contraceptive effect.Aim:To investigate the effect of PNE on reproductive hormones.Materials and Methods:The size and length of the combs of white leghorn day-old chicks treated with testosterone (0.5-1.5 mg/kg), cyproterone (3-30 mg/kg), or PNE (50-500 mg/kg) for 7 days, as well as cyproterone (10, and 30 mg/kg) on PNE-induced, and PNE (50-500 mg/kg) on testosterone-induced comb growth, were measured in the chick comb test. The effect of PNE the percentage change in an oviduct-chick weight ratio of Rhode Island Red layer day-old chicks treated with 17-β-estradiol (0.1-0.9 µg), PNE (30-300 mg/kg) or vehicle, for 6 days, was determined in the chick uterotrophic assay. Liver and kidney function was well lipid, and hematological profile tests were conducted to assess safety.Results:7-day treatment with PNE and testosterone increased significantly (P ≤ 0.01-0.001) while cyproterone significantly decreased (P ≤ 0.001) comb growth dose-dependently. Qualitatively, testosterone and PNE treatment resulted in relatively brighter red combs. Cyproterone caused significant inhibition (P ≤ 0.001) of both testosterone and PNE-induced comb growth. Co-administration of testosterone and PNE suppressed comb growth significantly (P ≤ 0.001). Administration of 17-β estradiol and PNE increased (P ≤ 0.001) oviduct-chick weight ratio dose-dependently. No significant changes were observed in assessing liver and kidney function, lipid profile, and hematological parameters.Conclusion:PNE exhibits both androgenic (partial testosterone agonist) and estrogenic activity. It has no detrimental effects on the blood, liver, and kidney tissue with prolonged use.

Apilarnil reduces fear and advances sexual development in male broilers but has no effect on growth

1. An experiment was conducted to determine the possibility of stimulating sexual development at an early age in male and female broiler chickens by administration of apilarnil, a natural bee product, in the pre-pubertal period. 2. From 28 to 55 d of age, birds were given apilarnil orally. The effects of low (2.5 g/bird) and high (7.5 g/bird) doses of apilarnil on growth performance, testicular weight, secondary sexual characteristics, blood lipids, testosterone and fearful behaviour were evaluated. 3. Apilarnil administration did not cause a positive effect on growth performance of male and female broilers suggesting that apilarnil did not have an anabolic effect. 4. Apilarnil administration suppressed blood glucose and cholesterol. 5. Birds receiving apilarnil remained immobile for a shorter period in a tonic imobiliy test and showed less home-cage avoidance responses suggesting a lower level of fearfulness. 6. Increases in testicular weight, testosterone concentration and comb growth in males receiving apilarnil implied that it stimulates the sexual maturation at an early age. However, a similar stimulation of secondary sexual characteristics was not observed in females.

Transient regime of Kerr-frequency-comb formation

Temporal growth of an optical Kerr frequency comb generated in a microresonator is studied both experimentally and numerically. We find that the comb emerges from vacuum fluctuations of the electromagnetic field on timescales significantly exceeding the ringdown time of the resonator modes. The frequency harmonics of the comb spread starting from the optically pumped mode if the microresonator is characterized with anomalous group velocity dispersion. The harmonics have different growth rates resulting from sequential four-wave mixing process that explains intrinsic modelocking of the comb.

Reproductive status in broiler breeder males is minimally affected by a mid-cycle increase in photoperiod

1. Broiler breeder males were reared on 8-h photoperiods, transferred to 12 h at 20 weeks, and either maintained on 12 h or further transferred to 14, 16, 18, 20 or 22 h at 40 weeks to determine whether reproductive status and the timing of the onset of adult photorefractoriness is influenced by photoperiod during the breeding cycle. 2. No photoperiodic effect was observed on sperm concentration although the combination of large variation within a treatment and the lack of a semen sample from some males at each collection may have masked small differences and indicates that perhaps fertility in individual males fluctuates naturally during the breeding season. 3. The rate of comb growth to, and testicular weights at, 60 weeks were not significantly different between treatments. 4. Plasma testosterone concentration at 60 weeks of age declined linearly with photoperiod between 12 and 22 h, suggesting that in the birds exposed to the more stimulatory photoperiods after 40 weeks, hypothalamic-pituitary-gonadal activity shut down earlier. 5. An increase in photoperiod at 40 weeks of age appears to advance the onset of photorefractoriness in male broiler breeders, evident from the decline in testosterone concentration with increasing photoperiod; it is however insufficient to affect sperm concentration or comb area.

Multiple aspects of condition influence a heritable sexual trait: a synthesis of the evidence for capture of genetic variance in red junglefowl

A long-standing question in the study of sexual selection is: if an attractive male trait signals heritable aspects of quality, how does genetic variation associated with that trait persist in the face of directional selection? It has been proposed that sensitivity to condition in general could allow a sexual signal to show heritable variation even under persistent directional selection. The multitude of genes underlying components of condition present a large target for mutation, and so genetic variance in condition may not be readily exhausted by selection. Insights gained in studies of the red junglefowl are relevant to this hypothesis, and provide a model for research in other systems. The fleshy comb of male red junglefowl is among the best-studied sexual signals. Multiple components of condition, such as health, immune function, testosterone, and social status, influence comb growth, and, in the present study, we provide the first comprehensive integration of this large body of evidence to lay out the compelling case for condition-dependence of the junglefowl comb. Variation in comb size is heritable and, most important to this issue, is genetically correlated with heritable variation in a body condition index. Although understanding of the red junglefowl's comb is far from complete, it exceeds our understanding of many other sexual signals and provides an empirical model for the study of condition-dependent signals in general. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 651–660.

Comb Growth During Sexual Maturation in Female Broiler Breeders

The process of sexual maturation in the chicken is associated with an increase in circulating estradiol-17β concentration. Researchers often rely on frequent blood sampling to measure estrogen concentration and thus to monitor the process of sexual maturation. Although reliable, this method is invasive to the animal and is not a practical technique for use on a farm. Sexual maturation also promotes the development of the comb and wattles on the chicken. The objective of this experiment was to evaluate an animal friendly and simple alternative to assess the rate of sexual maturity in female meat-type chickens by measuring the growth of the comb.Cobb-500 broiler breeder pullets were measured for comb growth by taking a digital image of the bird’s profile at 2-d intervals beginning at 20 wk of age. The images were subjected to analysis, and the height, length, and area of the comb were assessed. Blood samples were taken at 4-d intervals to correlate comb growth with plasma estradiol-17β concentration. Photostimulation occurred at 22 wk of age. Comb growth correlated positively with plasma estrogen concentration, but an even higher correlation was found with comb size and days to sexual maturity. Assessing changes in comb growth has the potential to be used as a tool for timing sexual maturation within a breeder flock.

Social mediation of sexually selected ornamentation and steroid hormone levels in male junglefowl

Honest signals in sexual selection may be maintained by a variety of mechanisms. Comb size in male red junglefowl, Gallus gallus, a well-known predictor of female mate choice, is mediated by health and condition. Social status has also been shown to mediate comb size. To determine whether hormones related to male dominance behaviour might be related to social status and comb size, we monitored changes in plasma levels of testosterone and corticosterone following manipulation of social status. We removed young adult male junglefowl from their all-male flocks and placed them either in individual cages or in smaller flocks. We measured comb size and other morphological variables, as well as testosterone and corticosterone levels, before and after the manipulation of social status. Males in small flocks showed reduced comb growth, increased corticosterone and decreased testosterone levels compared with individually housed males. Within flocks, comb size was positively related to dominance rank and to testosterone level, although not always significantly. However, dominance rank was unrelated to either corticosterone or testosterone levels. In isolated birds, testosterone level was not related to comb size. Corticosterone level was not related to comb size in either treatment group. Our results are consistent with social mediation of comb size and testosterone and corticosterone levels, but it is unclear whether these hormones contribute to the observed social limitation of comb length. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .

The Suppressive Effects of Testosterone on Growth in Young Chickens Appears to be Mediated via a Peripheral Androgen Receptor; Studies of the Anti-Androgen ICI 176,334

ICI 176,334 is a nonsteroidal anti-androgen that has been shown to selectively block peripheral androgen receptors in rats and is presumed to do so in chickens. In chickens, androgens stimulate secondary sexual characteristics (e.g., comb), but inhibit growth and the immune tissues. The present study examined the effect of dietary ICI 176,334 (5 or 25 mg/kg body weight) on growth in chickens in the presence or absence of testosterone treatment (as 1-cm long silastic implants). Treatments began at 2 wk of age and continued through 6 wk of age. Testosterone alone reduced body growth (average daily gain and shank-toe length, together with weights of the body, skeletal muscle, and the bursa of Fabricius, an immune tissue), and stimulated comb development. At the low dose (5 mg/kg), ICI 176,334 alone had no effect on body growth or organ weight with the exception that comb weight was reduced. At the high dose (25 mg/kg), ICI 176,334 decreased growth (body weight, average daily gain, and shank-toe length) and organ weights (breast muscle, bursa of Fabricius, testis, and comb weights). This effect may represent a toxicity. As might be expected with an anti-androgen, ICI 176,334 (at either 5 or 25 mg/kg) completely suppressed the stimulation of comb growth evoked by testosterone. Similarly, ICI 176,334 (5 mg/kg) overcame, albeit partially, the growth-suppressive effects of testosterone (on body weight, average daily gain, shank-toe length, and breast muscle weight) and also had inhibitory effects on the weights of the testis and bursa of Fabricius. The anti-androgen, ICI 176,334, did not influence the reduction in circulating concentrations of luteinizing hormone occurring after testosterone treatment. The present data are consistent with the growth-suppressive effects of testosterone in chickens being mediated via a peripheral androgen receptor. No effects of either testosterone or ICI 176,334 were observed on circulating concentrations of insulin-like growth factor-I despite the marked changes in growth rate.

Biodegradation kinetics and fate modelling of pentachlorophenol in bioaugmented activated sludge reactors

The growth and biodegradation kinetics of Mycobacterium chlorophenolicus comb nov. was studied in a series of batch experiments in the laboratory to identify and quantify the significant factors for its bioreactor performance. A mathematical model was formulated taking into account the degradation of primary and secondary substrate, as well as the growth of nonspecific and specific biomass. Using model parameters determined by the batch tests, the model was validated by simulations of a continuous flow experiment with bioaugmentation of the PCP-degrading culture in 2 activated sludge systems. A novel technique using immunofluorescence microscopy for quantifying the pure culture made it possible to evaluate the specific PCP degradation rates related to the PCP-degrading culture. The comparisons showed an excellent agreement for the total PCP removal, although there were some over- and underestimations of sorption and biodegradation as individual removal processes. The specific first order biodegradation rate constants were about 3 times higher in the bioaugmented systems that in batch experiments with the added culture alone. Even rough estimates for specific biodegradation rate constants may give meaningful predictions of the fate of specific organic compounds in wastewater treatment processes. For practical engineering and management purposes this may in many cases be adequate. The study highlighted the importance of reporting operating conditions in experiments from which biodegradation kinetic parameters such as Y, μ m and K S were derived.

Effect of Gonadal Steroids on Bone and Other Physiological Parameters of Male Broiler Chickens

Comparative studies of the effects of estradiol, progesterone, testosterone, cholesterol, and megestrol on juvenile chickens were carried out to determine their effects on bone and other physiological parameters. The chickens were implanted at 6 wk of age with ethylene-vinyl acetate copolymers containing steroids equivalent to a weekly dose of 10 mg/kg body weight for 3 consecutive wk. Estradiol caused a gain in body weight and relative liver weight but suppressed the growth of comb and testis. It also increased several serum variables, including triglycerides, cholesterol, calcium, phosphorus, and iron, and reduced testosterone levels. Testosterone produced an increase in comb weight and decreased both testicular and bursal weights. Growths of testis and comb were suppressed in progesterone-implanted chickens, as was the level of serum testosterone. Megestrol stimulated liver growth and increased serum testosterone levels. The lengths, relative weights, diaphyseal diameters, and ash percentages of both femur and tibia did not change significantly due to any treatment except that estradiol reduced tibial weight. Both progesterone and megestrol increased fibular growth plate alkaline and tartarate-resistant acid phosphatase activities. Other steroids did not affect these or the levels of calcium and of phosphorus of the fibular growth plate. Only testosterone caused a marked increase in the breaking strengths of both femur and tibia in all three parameters, i.e., load at yield, Young's modulus, and stress at yield responses. These findings suggest that the effects of steroids on bone in juvenile chickens may be limited.

Response of Broiler Breeder Females to Feed Restriction Below Recommended Levels.: 3.Characterizing the Onset of Sexual Maturity

The objective of this study was to characterize how the physical attributes associated with sexual maturity would be affected by feed allocation as female broiler breeders passed through the pullet-layer transition period. Treatments consisted of five feeding programs, or body weight goals, during the period of 0 to 20 wk of age. Those were 8% above breeder standard, standard (primary breeder recommended body weights), and 8, 16, and 24% below standard. The characteristics measured included body and fat pad weights, pubic spread, comb development, head score (comb and wattle appearance), shank length, total plasma lipid concentration, ovary weight, oviduct weight, bursa of Fabricius weight, and age at sexual maturity.The generalized effect of increased severity of the feed restriction programs was to delay the birds’ development without altering their ultimate physiological values. The exceptions to this were relative body weight and shank length after maturity, which were reduced in the most severely restricted birds. Measurements of pubic spread and comb growth and subjective scores of head appearance would be useful and easily obtained information when estimating the progression of a flock toward sexual maturity.

Sexual dimorphism in avian hepatic monooxygenases

Adult white Leghorn chickens exhibited a sexual dimorphism in hepatic microsomal monooxygenases determined from the concentrations of total cytochromes P450 and b 5, and the metabolism of drug (hexobarbital, coumarin and ethoxyresorufin) and steroid (androstenedione and testosterone) substrates that were 2- to 4-fold greater in roosters than in hens. Caponizing at 6 weeks of age reduced the activities of the monooxygenases to levels comparable to those found in intact hens. In spite of the fact that testosterone replacement maximally stimulated comb growth in the capons and elevated (i.e. masculinized) hepatic monooxygenase activities in the hens to male-like levels, androgen replacement was ineffective in increasing the subnormal enzyme levels in the capons. While the failure of testosterone administration to restore monooxygenase levels in the capons may be explained by the immaturity of the birds at orchiectomy, the present results demonstrate, that like some mammals, birds may display gender differences in hepatic monooxygenases that are regulated by the testes.