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ABSTRACT: Red light (RL) can enhance egg production in poultry. CircRNAs play a crucial role by serving as transcriptional regulators. However, their role in influencing follicle development in White King pigeons remains unexplored. In this study, 54 paired White King pigeons were chosen and divided into RL and white light (WL) groups, each with 3 subgroups. The egg production of paired pigeons in each replicate was recorded for 45 d, and the characteristics of follicle development were monitored during the laying interval (LI). The granulosa cell layer from follicles of the second-largest follicle (F2) was collected, and high-throughput sequencing was performed to elucidate the molecular mechanism of follicle development in pigeons. The study confirmed that RL enhances egg production in pigeons. Additionally, under RL, the F2 follicle was selected, while under WL, small follicles were kept on the third day (LI3). A total of 5,510 circRNAs were identified across all samples, revealing differentially expressed circRNAs (DECs) in various comparisons: 627 in RF1 vs. WF1, 900 in RF2 vs. WF2, 606 in RF1 vs. RF2, and 937 in WF1 vs. WF2. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that host genes of DECs were enriched in pathways like steroid hormone biosynthesis, oocyte meiosis, GnRH signaling pathway, and apoptosis pathway. Moreover, circRNA_5497, circRNA_2016, and circRNA_3328 were common DECs across 4 groups, sharing miRNA binding sites with follicle selection-associated genes. In conclusion, our findings suggest that RL promotes egg production by stimulating follicle selection during LI, offering insights into the regulatory mechanisms of circRNAs in follicle selection under RL. This knowledge can help enhance the reproductive performance of pigeons.

ABSTRACT: The egg-laying interval (LI) directly reflects the laying performance of breeding pigeons, influenced by reproductive hormones. This study aimed to assess reproductive hormone levels in serum and the expression of related genes and their receptors in the hypothalamus and pituitary gland in 4 stages: first (LI1), third (LI3), fifth (LI5), and seventh (LI7) days. The results showed that serum gonadotropin-releasing hormone (GnRH) level decreased from LI1 to LI7 (P < 0.01) and peaked in LI1. The serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels stayed at high levels from LI1 to LI5. The FSH level decreased slightly from LI5 to LI7 (P > 0.05), but the LH level decreased rapidly (P < 0.01). The prolactin (PRL) levels significantly increased in LI5 (P < 0.01) compared with LI1 and then stayed at a high level. The GnRH1 expression in the hypothalamus had no significant change in LI (P > 0.05). However, the GnRHR first decreased from LI1 to LI3 (P < 0.05) and then increased. The FSH mRNA level in the pituitary gland decreased from LI1 to LI3 and slightly increased in LI5 (P > 0.05). The change pattern of FSHR was similar to that of FSH and peaked in LI5 (P < 0.05). The LH expression level was the highest in LI5 and significantly higher than that in LI3 and LI7 (P < 0.05). However, the LHR mRNA level decreased in LI (P < 0.05). The expression patterns of PRL and PRLR were similar; they were upregulated in LI and peaked in LI7 (P < 0.01). The expression pattern of GnRHR was similar to that of FSH, LH, and FSHR, suggesting the critical role of GnRHR in LI. Furthermore, the expression levels of these genes peaked in LI5, closely correlating with the maturation of the first largest follicle in pigeons. PRL–PRLR signaling inhibited GnRH activity to promote ovulation. This study provided a basis for further investigating the molecular mechanisms underlying the regulation of reproduction in pigeons.

ABSTRACT: Paired pigeons only lay 2 eggs in a laying period, which is closely related to ovarian follicle development, but this process is not well understood. In this study, 60 pairs of 12-mo-old White King pigeons were selected and serum and follicles were collected at 4 stages of laying interval (LI), including the first (LI1), the third (LI3), the fifth (LI5), and the seventh day (LI7). Morphological results showed that paired pigeons normally had 2 preovulatory follicles and the second-largest follicle (F2) developed from LI3 and had been selected in LI5. Prehierarchical follicles were coupled and hierarchical, which was in accordance with its clutch size. The P4 concentration increased gradually from LI1 to LI5, reaching a maximum of 30.67 ng/mL in LI5 and decreasing to 27.83 ng/mL in LI7 (P < 0.05). The levels of T in LI1 and LI5 were higher than LI3 and LI7 (P < 0.05), although there was no significant difference in E2 in LI (P > 0.05), but it stayed at high levels. In the TCs of the largest follicle (F1), HSD3B1 mRNA and HSD17B1 mRNA levels peaked in LI7. The expression pattern of CYP17A1 and CYP19A1 was similar, increasing from LI3 to LI5 and then decreasing. In the TCs of F2, the expressions of HSD3B1 and CYP17A1 had no significant difference between LI5 and LI7 (P > 0.05), while the expression pattern of HSD17B1 and CYP19A1 was the opposite. In TCs of SF1, HSD3B1 mRNA level peaked in LI3 while CYP19A1 mRNA levels peaked in LI7. The expression of CYP17A1 had a minor change (P > 0.05) and the expression pattern of HSD17B1 was similar to F1. It was concluded that the morphological characteristics of follicles during the LI for the first time, including the number and diameter of small follicles (SFs) and hierarchical follicles in pigeon and the concentrations of steroid hormones and expressions of steroidogenic genes in TCs of different follicles could explain the growth and selection of 2 preovulatory follicles. This study facilitates further research into the regulation of ovulation and egg production in pigeons.

ABSTRACT: This experiment investigated the effects of different dietary starch sources on the growth and glucose metabolism of geese. A total of 240 healthy 35-day-old male geese were selected and randomly divided into 4 groups, with 6 replicates per group and 10 geese per replicate. Four types of diets were prepared, with glutinous rice (rapidly-digestible starch), corn, indica rice and high amylose as their starch sources, and fed for 28 d. Results showed that after consuming different feeds, the blood glucose of geese first increased and then decreased, reaching its maximum value 0.5 h after feeding, and there were significant differences between the groups (P < 0.05). The body weight of the corn and indica rice group geese at 63 d was higher than that of the high amylose group (P < 0.05). The serum total cholesterol (TCHO) content in the glutinous rice and corn groups was higher than in the high amylose group (P < 0.05). The serum insulin content in the glutinous rice group was lower than in the corn and high amylose groups (P < 0.05), while the glucagon content was higher (P < 0.05). The α-amylase activities of the pancreas, jejunal chyme, and jejunal mucosa in the glutinous rice group were higher than in the indica rice and high amylose groups (P < 0.05). The liver glycogen content in the glutinous rice group was higher than the other groups (P < 0.05). The liver glucose-6-phosphate dehydrogenase (G-6-PD) content in the glutinous rice group was higher than the high amylose group's (P < 0.05), but the glycogen synthase kinase-3 β (GSK-3β) content was lower (P < 0.05). In conclusion, the corn and indica rice diets had a positive effect on the growth performance of the geese, while the high amylose diet had a negative effect. The glutinous rice diet leads to rapid release of glucose, strengthening glucose metabolism pathways such as glycogen synthesis and the pentose phosphate pathway, and further influencing lipid metabolism.

ABSTRACT: The investigation aimed to explore the suitable amino acid (AA) supplementation pattern for goslings under low-protein diets. A total of 364 1-day-old male goslings were randomly divided into 4 experimental groups, with 7 pens containing 13 goslings each. The 4 groups were control (CP, 18.55%), LPM (CP, 15.55% + major AA), LPA (CP, 15.55% + all AA), and LPR (CP, 15.55% + AA content reduced proportionally to the control's CP). The corn-soybean meal diets are formulated according to the ideal AA model of goose and its nutritional requirements. The results indicated that the ADG and BW were the lowest, and the F: G was the highest in LPR (P < 0.05); the other three groups were not significantly different (P > 0.05). The ADFI and mortality were not different among all the groups (P > 0.05). Among the AA content in serum and breast muscle, lysine in serum significantly decreased compared with the control (P < 0.05). The UREA content was approximately 2-fold higher in the LPR group than in the LPM and LPA groups (P < 0.05). No difference in IgA, IgG, IgM, and IgE levels was observed among the groups (P > 0.05). The nitrogen excretion was decreased in LPM and LPA compared to the control and LPR (P < 0.05). Nitrogen deposition did not differ among groups (P > 0.05). Nitrogen utilization was highest in the LPA and LPM groups, followed by the control group and LPR (P < 0.05). In conclusion, the patterns of supplementation of major AA and all AA in low-protein diets (CP, 15.55%) had no adverse effect on the growth performance compared with the control (CP, 18.55%) of the goslings. Besides, the two patterns could decrease nitrogen excretion and increase nitrogen utilization. Furthermore, from the perspective of dietary cost and environmental protection, the pattern of supplementing major AA in a corn-soybean meal low-protein diet is suggested.

ABSTRACT: The objective of this experiment was to investigate the effects of betaine on growth performance, serum parameters, intestinal health, and immune performance of goslings in response to lipopolysaccharide (LPS) challenge. A total of 168 healthy male 15-day-old Jiangnan White Goslings were randomly divided into 4 groups, with 6 replicates per treatment and seven goslings per replicate. A 2 × 2 factorial arrangement included 2 factors, that is, LPS challenge (injection of LPS or physiological saline) and betaine (added 0 or 0.06% betaine in diet). The results indicated that LPS challenge significantly reduced the average daily feed intake (ADFI), average daily gain (ADG), and body weight (BW) at 21 D of the goslings, while dietary betaine supplementation tended to increase the ADFI during the LPS stress period (P = 0.08) and BW at 21 D of the goslings (P = 0.09). The LPS-challenged goslings showed higher pro-inflammatory cytokines (interleukin-1 [IL-1β], interleukin-6 [IL-6], tumor necrosis factor-α (TNF-α), and Interferon-gamma [IFN-γ]) and lower anti-inflammatory cytokine (Interleukin-10 [IL-10]) (P < 0.05) at 21 D of age. Dietary betaine supplementation alleviated LPS-induced increase in pro-inflammatory cytokines. The LPS challenge significantly decreased duodenal and jejunal villus height (VH) and villus height and crypt depth ratio (VCR), while the addition of betaine significantly increased duodenal VH and VCR (P < 0.05). On the other hand, addition of betaine significantly alleviated decline of enzyme activity on lipase, amylase, trypsin, and chymotrypsin in the intestinal of goslings. The LPS challenge significantly increased the content of serum D-lactic acid (D-LA) and the activity of diamine oxidase (DAO) at 21 D of the goslings. The LPS challenge and betaine addition significantly increased the mRNA expression of Occcludin (OCLN) in jejunal mucosa at 28 D of the goslings (P < 0.05). In conclusion, our research demonstrated that betaine can alleviate the decline of growth performance and immune performance in goslings caused by LPS. The results also indicate betaine possesses anti-inflammation properties and improves intestinal barrier functions. We recommend that 0.06% betaine be added into the diet to improve the intestinal health and immune performance of goslings.

ABSTRACT: The aim of this study was to investigate the effects of dietary paddy rice on growth performance, carcass traits, bare skin color, and nutrient digestibility in geese. A total of 300 twenty-eight-day-old male goslings were randomly divided into 5 treatment groups with 6 pens containing 10 goslings each. The geese were raised for 42 d on feed with 0% (control), 13, 26, 39, or 52% dietary paddy rice inclusion. Body weight and feed intake per pen were recorded from the arrival of goslings to the end of the trial. On d 70, two goslings were selected from each pen, one of which was used to measure slaughter performance, meat quality, meat proximate composition, and bare skin color, and one was used to determine nutrient utilization. The results showed that goslings fed a diet containing 26, 39, and 52% paddy rice had a higher final body weight, average daily feed intake, and average daily gain than those in the control group (P < 0.05). The abdominal fat yield in dietary paddy rice groups was higher than that of the control group (P < 0.05). There were no effects on the moisture, protein, and fat contents of breast and thigh muscle among the five treatments (P > 0.05). Compared to the control group, the breast muscle of geese fed the paddy rice had a lower L* value and a higher a* value (P < 0.05). Dietary paddy rice decreased the bill score of geese (P < 0.05). Geese in the paddy rice groups exhibited higher total starch digestibility than geese in the control group (P < 0.05). The digestibility of energy, crude protein, crude fat, crude fiber, NDF, and ADF did not differ between groups (P > 0.05). In conclusion, paddy rice is an excellent energy source in geese diets and could improve the growth performance, breast muscle color, and utilization of total starch but increase the abdominal fat yield and decrease the bill color of geese.

In this study, we evaluated the body fat distribution and fatty acid composition of muscles and adipose tissues of Yangzhou geese, including thirty 60-day-old goslings (15 males and 15 females) and 20 320-day-old geese (10 males and 10 females). Adipose tissues of Yangzhou geese were distributed widely and could be divided into 5 types: subcutaneous fat, abdominal fat, sartorial fat, neck fat, and mesenteric fat. Higher contents of abdominal fat, sartorial fat, neck fat, and mesenteric fat but a lower content of subcutaneous fat were found in adult geese than in goslings (P ≤ 0.05). Adult female geese deposited more fat than adult male geese (P ≤ 0.05). No difference was found in the fat distribution and fat content between male and female goslings (P > 0.05). The breast muscle of adult geese was characterized by a higher content of total monounsaturated fatty acids (ΣMUFAs) and a lower content of n-6 polyunsaturated fatty acids (ΣPUFAs n-6) than that of goslings (P ≤ 0.05). Lower concentrations of total saturated fatty acids and ΣPUFA were found in adult female geese than in female goslings (P ≤ 0.05). In comparison with adult female geese, the breast muscle of adult male geese had higher total saturated fatty acids and stearic acid (P ≤ 0.05). For the thigh muscle, adult female geese had a higher ΣMUFAs content than adult male geese (P ≤ 0.05). In adipose tissues, adult geese had a higher Σn-6/Σn-3 ratio but had lower contents of erucic acid, linolenic acid, arachidonic acid, docosatetraenoic acid, and ΣPUFA n-3 than goslings, and adult female geese had a higher ΣMUFAs content than adult male geese (P ≤ 0.05). In conclusion, adult geese, especially adult female geese, accumulated more fat than goslings. Both age and sex affected the fatty acid composition of muscles and adipose tissues in geese. This research provides essential information not only for the nutritional evaluation of geese but also for the consumption and processing of goose products.

The apparent metabolizable energy (AME), AME corrected to zero-nitrogen retention (AMEn), and net energy (NE) values of 2 corn samples both stored for 3 yr were determined in laying hens with reference diet substitution method. Reference diet was formulated according to standard layer requirement, and test diets contained 50% of corn samples and 50% of the reference diet. Fifty-four Hy-Line Brown hens at the age of 36 wk were used. The heat production and energy metabolism of birds were measured in open-circuit respiratory chambers with 6 replicates (3 birds per replicate) per diet in a randomized design. Birds were fed experimental diets for 7 D in the chamber as adaptation. During the following 3 D, feed intake, metabolizable energy value, nitrogen balance, energy balance, egg production, O2 consumption, CO2 production, and energy efficiency were determined. The AME values of corn 1 and corn 2 were 3,485 and 3,675 kcal/kg DM, respectively. The corresponding AMEn values were 3,452 and 3,596 kcal/kg DM, and the NE values were 2,575 and 2,693 kcal/kg DM, respectively. The NE:AME ratios of corn 1 and corn 2 were 74.4 and 73.3%, respectively. The NE:AMEn ratios of corn 1 and corn 2 were 75.0 and 74.9%, respectively. The AME, AMEn, and NE values of the 2 corn samples both stored for 3 yr were lower than the literature values for fresh corn.

ABSTRACT: This study was conducted to investigate the effects of lycopene (LYC) on mitochondrial oxidative injury and dysfunction in the liver of aflatoxin B1 (AFB1)-exposed broilers. A total of 192 healthy 1-day-old male broilers were randomly divided into 3 groups with 8 replicates of 8 birds each. Birds in the 3 groups were fed basal diet (control), basal diet with 100 µg/kg AFB1, and basal diet with 100 µg/kg AFB1 and 200 mg/kg LYC, respectively. The experiment lasted 42 d. The results showed that AFB1 decreased average daily body weight gain (ADG), average daily feed intake, and gain to feed ratio (G :F) compared to the control group, the LYC supplementation increased ADG and G/F compared to AFB1 group (P < 0.05). Broilers in the AFB1 group had lower mitochondrial glutathione (mGSH) concentration and glutathione peroxidase (GSH-Px), manganese superoxide dismutase (MnSOD), and thioredoxin reductase activities, and higher hydrogen peroxide (H2O2) and reactive oxygen species (ROS) concentrations than the control group (P < 0.05). The LYC increased mGSH concentration and GSH-Px and MnSOD activities, and decreased H2O2 and ROS concentrations compared to AFB1 group (P < 0.05). Broilers fed the AFB1 diet showed increased mitochondrial swelling and decreased adenosine triphosphate concentration than the control group, and LYC had opposite effects (P < 0.05). The AFB1 decreased the activities of mitochondrial electron transfer chain (ETC) complexes I, II, III, and V, downregulated the mRNA expression levels of hepatic MnSOD, thioredoxin 2, thioredoxin reductase, peroxiredoxin-3, peroxisome proliferator-activated receptor γ coactivator 1α, nuclear respiratory factor 1, and mitochondrial transcription factor A compared with the control group (P < 0.05), and LYC increased activities of mitochondrial ETC complexes III and V, and upregulated mRNA expression levels of these genes in comparison to AFB1 group (P < 0.05). In conclusion, the LYC protected broilers from AFB1-induced liver mitochondrial oxidative injury and dysfunction by stimulating mitochondrial antioxidant capacity and maintaining mitochondrial biogenesis.

ABSTRACT: Supplementation of betaine in the diet appears to regulate fatty acid metabolism and decrease fat deposition. This study aims to identify the effects of dietary supplementation of betaine on zootechnical performance, fatty acid synthesis, abdominal fat deposition, and morphology. Three hundred healthy, male, one-day-old Jiangnan White geese of similar body weight were randomly divided into 5 groups, with 6 replicates per treatment and 10 geese per replicate, and given the following amounts of supplementary betaine: 0 (group A), 600 mg/kg (group B), 1,200 mg/kg (group C), 1,800 mg/kg (group D), or 2,400 mg/kg (group E). Feed intake (FI), body weight (BW), abdominal fat and sebum thickness, clinical blood parameters, hepatic enzyme activity, and abdominal fat morphology were monitored during the experiment. All geese had free access to feed and water throughout the study. Our results indicate that supplementation of betaine increased zootechnical performance at 21 and 42 d of age. The percentage of abdominal fat and sebum thickness of geese at 63 d of age decreased linearly with the addition of betaine (P < 0.05). The triglyceride (TG) and total cholesterol (TCHOL) content of serum decreased with the increased level of betaine when measured at 63 d of age (P

ABSTRACT: A total of 960 male Ross 308 chicks (day-old) were used to investigate the effect of age on the relationship between metabolizable energy (ME) and digestible energy (DE) for broiler chickens. Bird growth variables, nitrogen retention (NR), nitrogen digestibility (ND), as well as the relative weight of liver, pancreas, and the gastrointestinal tract were determined. Practical diets that compared 2 cereals (corn and wheat) and exogenous xylanase (0 or 16,000 BXU/kg) were evaluated at 5 ages (7, 14, 21, 28, and 35 D) in a 2 × 2 × 5 factorial arrangement of treatments with 8 replicates per treatment and started with 30 birds per replicate. A randomized block ANOVA analysis of repeated measures was performed, and a 2 × 2 × 5 factorial structure was used to investigate the 2 dietary treatment factors (cereal type and the presence of xylanase) within the 5 bird ages (7, 14, 21, 28, and 35 D), and their interactions. Apparent metabolizable energy (AME) increased linearly from 7 until 28 D of age, but (P < 0.05) decreased at 35 D of age. Digestible energy was high at 7 D of age, then dropped and remained similar (P > 0.05) from 14 to 35 D of age. The AME: DE ratio was lowest (P < 0.05) at 7 D of age but there were no (P > 0.05) differences thereafter. Cereal type and xylanase supplementation did not (P > 0.05) change the ME: DE ratio. The results indicate that determining ME before 14 D of age may give absolute values that are lower than would be obtained with older birds. ME values that are determined on older broiler chickens may overestimate the energy availability of practical feeds used in broiler starter feeds.

ABSTRACT: Cottonseed meal (CSM), which is an unconventional protein material with abundant sources, high protein content, and a relatively cheap price, can be used in poultry diets. The aim of this study was to investigate the effects of CSM on slaughter performance, meat quality and meat chemical composition in Jiangnan White goslings. A total of 300 healthy 28-day-old male goslings were randomly divided into 5 treatments, with 6 pens containing 10 geese each. Five isonitrogenous and isocaloric experimental diets were formulated such that 0% (a corn-soybean meal basal diet, control), 25% (CSM25), 50% (CSM50), 75% (CSM75), and 100% (CSM100) protein from soybean meal was replaced with CSM (corresponding to 0, 6.73, 13.46, 20.18, and 26.91% CSM in the feed, respectively). On day 70, 1 goose from each pen (6 geese per treatment) was randomly selected and killed to measure the slaughter performance, meat quality, and the meat amino acid (AA) and fatty acid (FA) compositions. The results showed that dietary CSM did not affect the slaughter performance or meat quality of geese (P > 0.05). The fat content of breast muscle in the CSM100 group was higher than that in the control group (P < 0.05). A concentration of 13.46% or more dietary CSM increased the threonine content but decreased the cysteine content, and 20.18% dietary CSM also decreased the valine content (P < 0.05). Dietary CSM concentration had no effect on the content of total saturated FAs (SFAs, P > 0.05), but 20.18 and 26.91% dietary CSM increased the content of total monounsaturated FAs and decreased the content of total polyunsaturated FAs (PUFAs) and PUFA/SFA in the breast muscle of geese (P < 0.05). In conclusion, dietary CSM did not affect the slaughter performance or meat quality of geese, but the replacement of soybean meal with CSM in whole or high proportion altered the composition of AAs and FAs in breast muscle.

A dose-response experiment assessing 6 total dietary vitamin A (VA) levels (0, 3,000, 6,000, 9,000, 12,000, and 15,000 IU/kg) was conducted to study the effects of different levels of VA on growth performance and bone indexes of 0 to 28 d goslings. A total of 360 healthy 1-day-old goslings with similar body weights were randomly divided into 6 groups with 6 replicates in each group and 10 goslings in each replicate. The experiment duration was 28 d. The experimental results showed that the VA content in the serum and liver of gosling increased with increasing VA amount (P

A dose-response experiment with 5 total dietary threonine (Thr) levels (0.54, 0.64, 0.74, 0.84 and 0.94%) was conducted to study the effect of dietary Thr on growth performance and carcass traits of Yangzhou geese from 0 to 8 weeks of age. Three hundred 1-day-old Yangzhou goslings were randomly allocated to 15 pens with 20 birds (10 males and 10 females) per pen according to similar pen weight. There were 5 dietary treatments, consisting of 3 replicate pens. Weight gain, feed intake and feed/gain of geese from each pen were measured at 2-week intervals from 0 to 8 weeks. At 56 days of age, four geese (2 males and 2 females) were selected randomly from each pen and slaughtered to evaluate the carcass quality. The results showed that an increase in dietary Thr resulted in an increase and then a decrease in daily weight gain in both periods. Peak daily weight gain responses appeared in geese fed the 0.74%Thr diet in both periods (36.120 and 61.96 g, respectively). Thr supplementation significantly affected feed/gain in the 0-4 week period (P ≤ 0.045) and daily feed intake in the 5-8 week period (P ≤ 0.012). No significant linear or quadratic responses from Thr supplementation were observed in growth performance and carcass traits of geese except for eviscerated carcass percentage (quadratic effect, P ≤ 0.016). The optimal Thr requirement of Yangzhou geese from 0 to 8 weeks of age was 0.726% for eviscerated carcass percentage. The results of our experiment reported herein would document that the Thr requirements suggested by NRC (1994) for geese up to 8 weeks of age are safe estimates; they may slightly overestimate the requirements but not by a large margin.

O Vírus da Imunodeficiência Humana (HIV), infectando células TCD4 +, consegue comprometer gravemente o funcionamento do Sistema Imunológico, resultando em AIDS. Formulamos e analisamos três modelos matemáticos para este processo de infecção. Foi possível encontrar um limiar para a permanência do vírus na corrente sanguínea e evidenciar a necessidade da apoptose de células ativadas, após a eliminação do antígeno. Através da introdução de um termo de exaustão cumulativa (resultado da constante tentativa do sistema imunológico responder à infecção pelo HIV) também reproduzimos a diminuição do número de células T-CD4+ ao longo dos anos.

Os rotavíırus são considerados, atualmente, um dos mais importantes agentes causadores de gastroenterites e óbitos em crianças com menos de 5 anos no mundo. Ocorrem globalmente cerca de 125 milhões de episódios diarréicos por rotavírus a cada ano. Esses números alarmantes estimularam a busca por um controle desse vírus, mas para combatê-lo é necessário estudar seu comportamento, como ele penetra no organismo humano, como age dentro dele e como se espalha. Nesse trabalho apresenta-se um modelo matemático da interação do rotavírus com o sistema imunológico. O principal objetivo desse estudo é avaliar, comparativamente, o desempenho das respostas imunológicas humoral e celular. Com esse intuito analisa-se o modelo proposto, composto de equações diferenciais ordinárias não lineares de primeira ordem, para avaliar a ação do sistema imunológico a fim de eliminar o rotavírus.

Neste trabalho, foi desenvolvido um modelo matemático que visa descrever as interações entre bactérias lácticas produtoras de bacteriocinas e a Listeria monocytogenes no alimento. As bactérias lácticas produzem bacteriocinas que preservam alimentos por meio de exclusão competitiva com outros microorganismos nocivos, como a Listeria. A análise estática e a dinâmica do modelo, representado por um sistema de equações diferenciais ordinárias, fornecem informações sobre o comportamento das soluções, e, também, permitem estudar a possível ação do ácido láctico e da bacteriocina, produzidos pela bactéria láctica, na redução e inibição de atividade de Listeria no alimento.

Dengue is a human disease transmitted by the mosquito Aedes aegypti. A dengue epidemic could start when infectious individuals (humans or mosquitoes) appear and could propagate in areas previously colonized by the mosquitoes. In this work, we propose a model to study the dengue propagation using a system of partial differential reaction-diffusion equations. The human and mosquito populations are considered, with their respective subclasses of infected and non infected populations. We assume that the diffusion occurs only in the winged form, and the human population is considered constant. The cross-infection is modeled by the mass action incidence law. A threshold value, as a function of the model’s parameters, is obtained, which determines the endemic level of the disease. Assuming that an area was previously colonized by the mosquitoes, the spread velocity of the disease propagation is determined as a function of the model’s parameters. The traveling waves solutions of the system of partial differential equations are considered to determine the spread velocity of the front wave.

Water mites (Hydrachnidia) are a group of arthropods with a complex life cycle which includes larval and three nymphal stages. The mite larvae parasitize aquatic and semiaquatic insects, while deutonymphs and adult mites are predators of insect larvae and eggs. Since several families of water mites are associated with mosquitoes, there is an interest in the potential use of these mites as biological control agents of Aedes aegypti. The aim of this paper is to use mathematical modelling and analysis to assess the impact of predation and parasitism in the mosquito population by water mites. We discuss the fitness of water mites as biological control of mosquitoes by different scenarios that appear when we change the parasitism and predation parameters. High rates of parasitism and moderate predation can drive two species to a stable coexistence far from the extinction point.

Bactérias que vencem a barreira física (pele ou mucosas do trato digestivo e intestinal) provocam uma reação inflamatória localizada. Essa reação é a resposta do sistema imunológico inato para conter invasão de micro-organismos ao corpo humano. Desenvolve-se um modelo matemático para descrever essa resposta do sistema imunológico, levando em consideração a patogenicidade das bactérias. Aplicase os resultados para explicar a diferen¸ca de comportamento entre as bactérias estafilococos e estreptococos. O modelo mostra que quanto menor for a patogenicidade da bactéria, maiores são possibilidades de superar a resposta do sistema imunológico inato e causar uma infecção generalizada.

Os mecanismos de ação das células T, mediante a presença de um antígeno no organismo, são essenciais para a produção de anticorpos no combate a patógenos circulantes na corrente sanguínea. Este trabalho estuda um modelo matemático que explora os mecanismos de produção de anticorpos pelas células B, mediante a presença de um antígeno no organismo e mediada pela ação das células T, bem como a ação dos anticorpos. O modelo é composto por um sistema de equações diferenciais ordinárias não-lineares de primeira ordem, o qual descreve a interação das células B e T do sistema imunológico entre si e com o antígeno. O estudo das soluções em equilíbrio estacionário mostra a existência de uma região de parâmetros na qual três soluções de equilíbrio são biologicamente viáveis, sendo duas estáveis, as quais representam, respectivamente, a ausência de antígeno (solução trivial) e a sua existência em concentração maior, e uma intermedi ária instável, com concentração menor de antígenos, denominada “break point”. Fora desta região, apenas a solução trivial é biologicamente viável. Isso evidencia a resposta do sistema imunológico depender tanto do seu estado quanto da concentração de antígenos inoculados, concordando com o observado na prática.

Neste trabalho apresenta-se o desenvolvimento de um modelo matemático que descreve a ação do sistema imunológico adaptativo (a fim de eliminar elementos estranhos ao corpo), através das respostas humoral (produção de anticorpos pelas células B) e celular (ação de células T citotóxicas). Primeiro, mostra-se a dinâmica do crescimento do micro-organismo considerando limitação de suprimentos para sua replicação e, a seguir, a homeostasia das células do sistema imunológico. A despeito da simplicidade da dinâmica das populações de patógeno e das células, a descrição da interação de todas as populações torna-se altamente complexa. Assim, a apresentação do desenvolvimento de um modelo complexo de interação é justificada pela necessidade de sua simplificação.

Analisa-se um modelo compartimental para a transmisão de Leishmaniose que contempla o homem, cão e Lutzomyia como hospedeiros vertebrados e invertebrado, respetivamente. Deriva-se a expressão do número de reprodutibilidade basal. Estuda-se a estabilidade. Aplica-se o mesmo para simular a situação de zonas endêmicas no Estado de São Paulo.

Neste trabalho desenvolvemos e analisamos um modelo simples que descreve a interação do vírus HIV com o sistema imunológico (SI). O modelo considera apenas a ação de anticorpos para neutralizar vírus HIV circulante no sangue. Obtendo-se o valor de bifurcação, discute-se a possibilidade de SI eliminar HIV circulante.

We propose a mathematical model to assess the effects of irradiated male insects introduction in a previously infested region, taking into account the logistic recruitment of sterile male insects. The release of sterile male insects aims to displace gradually the natural (or wild) insect from the habitat. We discuss the suitability of this release technique when applied to peridomestic adapted Aedes aegypti mosquitoes which are transmitters of Yellow Fever and Dengue disease.

Neste trabalho propõe-se um modelo matemático do tipo SEIRE, com população constante, considerando a reinfecção dos indivíduos. Diferente da maioria dos modelos clássicos em epidemiologia, e principalmente por causa da hipótese de múltiplas infecções, o modelo apresenta uma bifurcação “backward”, o que pode resultar em um comportamento que não é o usual de um modelo baseado na lei da ação das massas. Ou seja, quando o número de reprodutibilidade basal, R0, esteja entre um valor crítico e um, podem surgir dois equilíbrios endêmicos além do equilíbrio trivial. Procura-se explorar o efeito das múltiplas infecções em conjun ção com o período de latência, mostrando a importância relativa entre eles. De um modo geral, quando a permanência dos indivíduos no estágio latente for muito lenta, como é o caso da tuberculose, as infecções múltiplas têm importância não só na prevalência, mas tembém na questão da erradicação da doença.

Neste trabalho, formula-se um modelo matemático para descrever a dinâmica de transmissão da Tuberculose (TB) e avaliar os fatores de impacto na sua epidemia e no seu controle. Com a finalidade de abordar vários aspectos da epidemiologia da TB da forma mais simples possível considera-se que, uma vez infectado, o indíviduo pode progredir para a doença rapidamente (“fast” TB) ou de forma mais lenta, pela reativação endógena (“slow” TB), ou então, adquirir uma nova infecção, pela reinfecção exógena. Os efeitos da vacinação e do tratamento são também analisados como estratégias de controle. Nossos resultados sugerem que o aumento na taxa de incidência da TB é devido à reativação endógena (por exemplo, pela infecção pelo HIV) e/ou à reinfecção exógena.

Neste trabalho desenvolve-se um modelo matemático compartimental e determinístico para analisar a dinâmica populacional da interação do inseto-praga Phyllocnistis citrella com seus inimigos naturais Galeopsomyia fausta e Ageniaspis citricola.

Estuda-se a dinâmica da população de mosquitos transmissor da dengue através de modelo matemático autônomo. Dependendo da hipótese admitida para a capacidade de oviposição, mostra-se a existência ou não de condições para a eliminação dos mosquitos por meio de controle aplicado na sua população.

O ciclo de vida do mosquito Aedes Aegypti, transmissor da dengue, é composto de qutro fases: ovo, larva, pupa e mosquito adulto. Com o intuito de quantificar cada uma dessas fases e medir o impacto das diferentes formas de controle utilizadas pela SUCEN, desenvolveu-se um modelo determinístico compartimental que descreve a dinâmica desta população e considera a dependência temporal de seus parâmetros.

Estuda-se a transmissão do vírus da dengue na população humana através de modelo matemático. Como o vírus é transmitido pelo mosquito Aedes aegypti, o modelo considera a interação entre duas populações.

Neste trabalho desenvolve-se um modelo matemático que descreve a dinâmica da reinfecção da rubéola e propõe a vacinação como estratégia de controle e/ou erradicação da doença em uma comunidade. Com o objetivo de analisar como a infecção ainda é mantida na população, mesmo existindo um programa de vacinação e revacinação em massa, é feita uma análise qualitativa do modelo determinando seus pontos de equilíbrios e a estabilidade destes pontos.

Estuda-se a dinâmica da transmissão da dengue na população humana acoplada à dinâmica do vetor mosquito. Considera-se a circulação de um único sorotipo na comunidade, sendo que as populações humana e de mosquitos são descritas por um modelo determinístico compartimental. Supondo que o encontro entre os infectantes e os suscetíveis acontece de maneira aleatória, estuda-se o efeito da ação dos mecanismos de controle (aplicados na população de mosquitos) sobre a doença para diferentes valores das forças de infecção.

Muitas infecções que ainda assolam a humanidade podem ser combatidas usando-se as vacinações em massa. O acúmulo de conhecimentos referentes à transmissão de infecções permitiu quantificar a sua dinâmica usando-se modelos matemáticos. Estes modelos, no entanto, não apenas descrevem a disseminação das doenças na comunidade, mas também podem ser preditivos quanto aos resultados de diferentes mecanismos de controle que são introduzidos nesta comunidade.

Neste trabalho, propomos um modelo matemático para descrever a dinâmica da transmissão vertical do HIV, assumindo que as mulheres suscetíveis tornam-se infectadas pelo HIV a uma taxa constante. O estudo analítico do modelo mostra que, mesmo existindo a transmissão vertical do HIV, a AIDS pode ser mantida na comunidade quando a taxa de natalidade da população e a idade reprodutiva das mulheres satisfazem determinadas condições.

Modelos matemáticos estão sendo utilizados para auxiliar na melhor compreensão do alastramento de doenças em uma comunidade.

Modelos Interespecíficos para Controle Químico de Áreas Foliares Lesionadas por Fungos

Neste trabalho estabelecemos uma caracterização do número de reprodutibilidade basal R0 para uma doença infecciosa de transmissão direta como sendo o raio espectral da derivada de Fréchet de um operador integral. Obtemos limites inferior e superior para R0 e condições suficientes para a unicidade da solução não trivial da força de infecção, que neste caso pode ser atingida como o limite de umaseqüência recursiva. Como aplicação, consideramos uma taxa de contato constante em todas as idades e obtivemos resultados clássicos bem como o esforço mínimo de vacinação necessário para a erradicação da doença.

Neste trabalho propomos um modelo matemático que descreve a transmissão da esquistossomose, incorporando imunidade concomitante e fatores ambientais como reguladores da transmissão, e uma estratégia de vacinação como mecanismo de controle.