Fibroblast growth factor-2 promotes in vitro activation of cat primordial follicles.

This study evaluated the effect of fibroblast growth factor-2 (FGF-2) on the morphology, primordial follicle activation and growth after in vitro culture of domestic cat ovarian tissue. Ovaries (n = 12) from prepubertal domestic cats were collected and fragmented. One fragment was fixed for histological analysis (fresh control). The remaining fragments were incubated in control medium alone or with 10, 50 or 100 ng/ml FGF-2 for 7 days. After in vitro culture, the following endpoints were analyzed: morphology, activation by counting primordial and developing follicles, and growth (follicle and oocyte diameters). Treatment with 100 ng/ml FGF-2 maintained (P > 0.05) the percentage of normal follicles similar to fresh control. Follicle survival was greater (P < 0.05) after culture in 100 ng/ml FGF-2 than in 50 ng/ml FGF-2. The percentage of primordial follicles decreased (P < 0.05) and the percentage of developing follicles increased (P < 0.05) in all treatments compared with fresh tissue. The proportion of developing follicles increased (P < 0.05) in tissues incubated with 100 ng/ml FGF-2 compared with control medium and other FGF-2 concentrations. Furthermore, culture in 10 or 100 ng/ml FGF-2 resulted in increased (P < 0.05) follicle and oocyte diameters compared with fresh tissues and MEM+. In conclusion, FGF-2 at 100 ng/ml maintains follicle survival and promotes the in vitro activation and growth of cat primordial follicles.

Survival in crossbred lambs: Breed and heterosis effects.

The objective of this study was to estimate genetic and nongenetic effects affecting survival in crossbred lambs during 3 time periods: through 1 d of age ( = 7,933), 2 to 30 d of age ( = 5,370), and 2 to 60 d of age ( = 5,216) in a population being upgraded to the dairy breeds of East Friesian and Lacaune in which lambs were artificially reared on milk replacer. Survival was analyzed for lambs born in 14 yr from 1998 to 2011 using pedigree information from 14,339 animals born in 23 yr from 1989 to 2011. Date of death, sex, age of the dam, birth type, month and year of birth, and breed composition were recorded, and the proportion of retained heterosis was calculated for each animal. Lambs were crossbreds of 2 or more breeds with 14 breeds represented in the population. Due to low mean genetic contribution of the 12 nondairy breeds, they were placed into 2 groups: meat breeds (Hampshire, Suffolk, and Texel) and maternal breeds (Romanov, Finnsheep, Dorset, Targhee, Rambouillet, Polypay, Katahdin, Arcott Rideau, and Commercial). The proportion of individual retained heterosis was positively associated ( < 0.05) with lamb survival from 2 to 30 and from 2 to 60 d of age. The predicted increase in survival of F lambs compared to purebred lambs was +8.8 and +14.6%, respectively. Predicted survival of meat breed lambs and maternal breed lambs was greater ( ≤ 0.01) than Lacaune lambs during all 3 periods. Predicted survival of East Friesian lambs was consistently lower ( ≤ 0.01) than meat breed and maternal breed lambs during all periods. The predicted survival of East Friesian lambs was numerically greater but not significantly different from Lacaune lambs. There was a lower ( < 0.01) survival of females compared to males through 1 d of age (-5.6%), but females had higher ( < 0.01) survival than males in the other 2 periods (2 to 30 d = +3.3% and 2 to 60 d = +6.0%). Through 1 d of age, lambs of triplet and greater birth types had lower ( < 0.01) survival than single lambs (-6.2%), and lambs from 1-yr-old dams had lower ( < 0.01) survival than lambs from 2-yr-old dams (+4.5%). Estimates of heritability of lamb survival were 0.14 (SE = 0.03), 0.03 (SE = 0.04), and 0.06 (SE = 0.03) for the 3 time periods, respectively. An increase in the proportion of individual retained heterosis was the most important genetic factor associated with increased lamb survival in this study.

Tongue papillae morphology of brown-throated sloth Bradypus variegatus (SCHINZ, 1825) / Morfologia das papilas linguais de preguiça comum Bradypus variegatus (SCHINZ, 1825)

The Bradypus variegatus inhabits the forests of South America and feeds from leaves, branches and sprouts from different plants. Due to its diet and the lack of literature on the morphological aspect of Xenarthras, five Bradypus variegatus tongues from animals which died from natural causes were evaluated, and they came from Pará State Museum Emílio Goeldi and were donated to the Laboratory of Animal Morphological Research (LaPMA) from UFRA, for revealing the different types of papillae and epithelial-connective tissue. Macroscopically, the tongues presented elongated shape, rounded apex, body, root, median sulcus in the root's apex, and two vallate papillae. The mucous membrane of the tongue revealed a keratinized stratified pavement epithelium, while the ventral surface of the tongue was thin and smooth, not provided with any type of papillae. However, the dorsal surface of the tongue was irregular with the presence of three types of papillae: filiform, fungiform and vallate papillae. The filiform papillae found were of a simple type, presenting a rounded base, irregularly distributed with a larger concentration and development on the tongue's apex and body. The fungiform papilla showed a practically smooth surface with irregular format, with the presence of gustatory pores; these were found all over the dorsal surface, with larger concentration at the rostral part of the apex. Only two vallate papillae were observed disposed in the root of the tongue, surrounded by a deep groove, and revealing several taste buds. The tongues from Bradypus variegatus presented gustatory papillae similar to the ones described for other Xenarthras species and wild mammals...

A Bradypus variegatus habita florestas da América do Sul e alimenta-se de folhas, ramos e brotos de várias plantas. Em decorrência de sua dieta, bem como da escassez de literatura sobre aspectos morfológicos dos Xenarthras, avaliaram-se cinco línguas de Bradypus variegatus, que foram a óbito por causas naturais, provenientes do Museu Paraense Emílio Goeldi e doados ao Laboratório de Pesquisa Morfológica Animal (LaPMA) da UFRA, a fim de se elucidarem os diferentes tipos de papilas e a interface epitélio-tecido conjuntivo. Macroscopicamente, as línguas apresentaram formato alongado, ápice arredondado, corpo, raiz, sulco mediano do ápice à raiz e duas papilas valadas. A mucosa da língua revelou epitélio de revestimento pavimentoso estratificado queratinizado, enquanto a face ventral era delgada e lisa, desprovida de qualquer tipo de papila. Já a face dorsal apresentou-se irregular, com a presença de três tipos papilares: papilas filiformes, fungiformes e valadas. As papilas filiformes encontradas eram do tipo simples, com base circular, distribuídas irregularmente, com maior concentração e desenvolvimento no ápice e no corpo da língua. A papila fungiforme mostrou-se com superfície praticamente lisa e de formato irregular, com a presença de poros gustativos. Estas foram encontradas por toda a superfície dorsal, com maior concentração na parte rostral do ápice. Foram observadas apenas duas papilas valadas, dispostas na região da raiz da língua, com corpo rodeado por sulcos profundos e vários botões gustativos. As línguas de Bradypus variegatus apresentaram papilas linguais similares às descritas para outras espécies de Xenarthras e mamíferos selvagens...

Shelf life of cooked goat blood sausage prepared with the addition of heart and kidney.

This study focused on the effect of two packaging formats (vacuum packaging and over-wrap packaging) on the shelf life of cooked sausage prepared with blood, heart, kidney and goat meat fragments under storage at 4±1°C for a period of 90 days. The storage time and type of packaging significantly affected the chemical (pH, moisture, protein and TBARS number), physical (shear force) and microbial (mould and yeast) parameters of cooked sausage. Vacuum packaging maintained the microbiological and chemical qualities of cooked goat blood sausage for a longer period of time (63 days) compared to over-wrap packaging (41 days) and could be a viable alternative to refrigerated storage of the product for quality maintenance.

Ants' role (Hymenoptera: Formicidae) as potential vectors of mycobacteria dispersion / Comportamento de formigas (Hymenoptera: Formicidae) como vetores potenciais de dispersão de micobactérias

Ants are found worldwide playing an important environmental role. Some species are considered as agricultural pests and potential risk to human life and public health acting as pathogens carriers. Ants as Paratrechina longicornis and Camponotus spp. have been found inside hospitals. The aim of this study was the research of mycobacteria in 138 samples of ants (137 Paratrechina longicornis and only one Camponotus spp.) which got into the laboratories of tuberculosis diagnosis. These ants were suspended in sterile saline solution and inoculated into Petragnani and Stonebrink media, incubated at 37° C until 90 days and the isolates were identified as environmental mycobacteria (1 Mycobacterium fortuitum peregrinum, 1 Mycobacterium smegmatis) and 1 Mycobacterium tuberculosis complex. These results showed that ants should also act as mechanical vectors of mycobacteria dissemination in risk environments, reinforcing their significance in public health.

As formigas têm uma distribuição mundial e representam importante papel no ecossistema. Algumas espécies são consideradas pragas para a agricultura e um risco potencial à vida humana e à saúde pública veiculando mecanicamente agentes patogênicos. Formigas como Paratrechina longicornis e Camponotus spp. têm sido encontradas em ambientes hospitalares. O foco do presente estudo foi a identificação de micobactérias em 138 amostras de formigas (137 Paratrechina longicornis e apenas uma Camponotus sp.), que tiveram acesso a áreas de laboratórios de diagnóstico de tuberculose. Essas formigas foram suspensas em solução salina estéril que foi semeada em meios de Petragnani e Stonebrink, incubadas a 37º C por até 90 dias e as estirpes de micobactérias isoladas foram identificadas pelas técnicas clássicas como micobactérias ambientais (sendo 1 Mycobacterium smegmatis, 2 Mycobacterium fortuitum peregrinum e 1 Mycobacterium tuberculosis). Esses resultados mostram que as formigas podem também se constituir vetores de dispersão de micobactérias em ambientes de risco, reforçando sua importância em saúde pública.

Herdabilidade e correlaçäo genética entre perímetro escrotal, libido e características seminais de touros Nelore / Heritability and genetic correlation between scrotal circumference, libido and seminal traits in Nellore bulls

Dados de 273 touros Nelore nascidos de 1992 a 1998 e com idade média de 31 meses foram utilizados para estimar as herdabilidades do perímetro escrotal (PE), libido (Lib), motilidade (mot), vigor (vig), concentraçäo (con) e taxa de anormalidade seminal (ta) e as correlaçöes genéticas entre essas características. Com o uso do método da máxima verosimilhança restrita as estimativas de herdabilidade e respectivos erros-padräo foram 0,38±0,20 para PE, 0,33±0,20 e 0,31±0,20 para Lib com idade ou peso corporal no modelo, respectivamente, 0,01±0,10 para mot, 0,03±0,30 para vig, 0,00±0,50 para coN e 0,07±0,13 para ta. As correlaçöes genéticas entre PE e Lib foram 0,78 e 0,76, respectivamente, considerando-se ou näo o peso corporal no modelo. Correlaçöes genéticas entre PE e as características con, mot, vig e ta foram 0,99, 1,00, -0,14 e 0,99, respectivamente. Pode-se esperar resposta à seleçäo direta para PE e Lib e a seleçäo para uma das características resultaria em seleçäo para a outra. As baixas estimativas de herdabilidade para as características seminais indicam pequeno componente genético aditivo

Interaçäo genótipo-ambiente em algumas características produtivas de gado de corte no Brasil / Genotype environmental interaction in some growth traits of beef cattle in Brazil

Este estudo teve por objetivo medir o efeito da interaçäo genótipo-ambiente (IGA) em algumas características de crescimento em bovinos Nelore. Os dados foram coletados em duas fazendas, em regiöes distintas do Estado de Minas Gerais, Sul (faz I) e Noroeste (faz II), e correspondem aos pesos de 2.896 animais à pré-desmama (PD), 2.605 à desmama (DM) e 1.522 à pós-desmama(SA), com 9.911 no arquivo de genealogia. Apenas animais criados em pasto foram utilizados para as análises. Os efeitos de época de nascimento (mês-ano), sexo e fazenda foram reunidos em grupos de contemporâneos. Os componentes de (co)variância foram estimados pelo programa MTDFREML. Nas análises conjuntas de duas características as estimativas de herdabilidade dos efeitos diretos foram 0,24, 0,16, e 0,17 (faz I) e 0,25, 0,24, e 0,17 (faz II), para PD, DM e SA, respectivamente. As correlaçöes de ordem dos valores genéticos entre fazendas para as características PD, DM e SA foram, respectivamente, 0,74, 0,76 e 0,51. Na mesma ordem, as correlaçöes genéticas entre fazendas foram 0,96, 0,95 e 0,53. Estes resultados näo evidenciaram efeito da IGA até a desmama, porém após a desmama seu efeito foi grande, sugerindo que se deva fazer uma avaliaçäo regional para escolha de reprodutores Nelore se se utilizar essa última característica como critério de seleçäo

Avaliaçäo agronômica de seis híbridos de sorgo (Sorghum bicolor (L) Moench) / Agronomic evaluation of six sorghum hibrids

Foram determinadas as produçös de matéria seca (MS) e de matéria natural (MN), as proporçöes de colmo, folhas e panícula em seis híbridos de sorgo, em plantas com o gräo em estádio leitoso/pastoso. Usou-se um delineamento inteiramente ao acaso, com quatro repetiçöes por tratamento (híbrido). A altura dos híbridos variou de 1,0 a 2,7m e a correlaçäo entre altura da planta e porcentagem de acamamento foi de 0,27. A porcentagem de MS do colmo variou de 20,8 a 29,4 e a correlaçäo entre MS no colmo e altura da planta foi de 0,31. Altura e porcentagem de MS do colmo näo influenciaram o percentual de acamamento. A produçäo de MS variou de 4,47 a 7,86 t/ha e a de MN de 13,4 a 31,1 t/ha. A porcentagem de colmo variou de 40,5 a 67 por cento, a de folhas de 12,1 a 21,6 por cento, e a de panícula de 20,9 a 40,6 por cento. Os híbridos de maior produçäo foram os de maior altura. Houve diferenças significativas entre os tipos de sorgo quanto a matéria seca do colmo e altura da planta, porém essas variáveis näo influenciaram o percentual de acamamento das diversas variedades de sorgo. O híbrido BRS70l destacou-se pela altura, baixo percentual de acamamento, elevado teor de matéria seca do colmo, elevada proporçäo de panícula e produçäo de MS

The genome sequence of the plant pathogen Xylella fastidiosa. The Xylella fastidiosa Consortium of the Organization for Nucleotide Sequencing and Analysis.

Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. Here we report the complete genome sequence of X. fastidiosa clone 9a5c, which causes citrus variegated chlorosis--a serious disease of orange trees. The genome comprises a 52.7% GC-rich 2,679,305-base-pair (bp) circular chromosome and two plasmids of 51,158 bp and 1,285 bp. We can assign putative functions to 47% of the 2,904 predicted coding regions. Efficient metabolic functions are predicted, with sugars as the principal energy and carbon source, supporting existence in the nutrient-poor xylem sap. The mechanisms associated with pathogenicity and virulence involve toxins, antibiotics and ion sequestration systems, as well as bacterium-bacterium and bacterium-host interactions mediated by a range of proteins. Orthologues of some of these proteins have only been identified in animal and human pathogens; their presence in X. fastidiosa indicates that the molecular basis for bacterial pathogenicity is both conserved and independent of host. At least 83 genes are bacteriophage-derived and include virulence-associated genes from other bacteria, providing direct evidence of phage-mediated horizontal gene transfer.

Prevalência e classificaçäo das afecçöes podais em vacas lactantes na bacia leiteira de Belo Horizonte / Prevalence and classification of foot problems in lactating dairy cows in Belo Horizonte, Brazil

Com o objetivo de avaliar a prevalência e classificar clinicamente as afecçöes podais, foram examinadas 469 vacas em lactaçäo de 10 fazendas da bacia leiteira de Belo Horizonte criadas em regime de confinamento. Entre elas, 142 vacas, consideradas afetadas, apresentaram 534 lesöes. A prevalência de vacas afetadas foi de 30,3 por cento. Das afecçöes podais, 66,7 por cento ocorreram nos membros posteriores e 33,3 por cento nos membros anteriores. Ocorreram 49,2 por cento lesöes nas unhas laterais e 50,7 por cento nas unhas mediais. Quanto ao escore de manqueira, 105 foram classificados como escore 1, 9 como escore 2, 15 como escore, 3,7 como escore 4 e 6 como escore 5. Maior incidência ocorreu nas vacas mais velhas, e näo se observou influência da fase de lactaçäo. A lesäo mais freqüente foi a erosäo de camada córnea, representando 48,5 por cento do total, seguida por dermatite interdigital (13,5 por cento) e pododermatite séptica (9,6 por cento). O elevado número de animais afetados permite concluir que as afecçöes podais em vacas em lactaçäo confinadas constitui um sério problema em fazendas na bacia leiteira de Belo Horizonte

Variaçäo temporal do efeito do bicromato de potássio na conservaçäo de amostras de leite destinadas à análise em laboratório central / Time effect of potassium bichromate upon milk composition prior to laboratory testing

Foram analisadas, pelo método do quadrados mínimos, 13.189 registros de controles leiteiros mensais de 467 vacas de seis grupos genéticos (cruzamentos HVB x Guzerá), distribuídas em 65 fazendas agrupadas em cinco sub-regiöes da Regiäo Sudeste. As amostras, com adiçäo de 0,1 por cento p/v de K2Cr2O7 eram enviadas ao Centro Nacional de Pesquisa em Gado de Leite (CNPGL) para análise dos percentuais de gordura (PG) e proteína (PP). O período coleta-análise (t) variou de 0 a 28 dias. Após análises preliminares, adotou-se um modelo estatístico incluindo os efeitos da sub-regiäo, grupo genético, ano e mês da coleta, com duas regressöes lineares com inclinaçöes diferentes (c1 e c2), em cada um dos períodos t<8 e t>=8 dias. As regressöes dentro de sub-regiäo foram homogêneas para PG mas näo para PP (P=0,003). Em média, para a Regiäo Sudeste, os coeficientes das regressöes c1 e c2, foram, respectivamente, para PG, 0,0007 mais ou menos 0,0061 e -0,0147 mais ou menos 0,0049 unidades percentuais por dia após a coleta e para PP, 0,0023 mais ou menos 0,0023 e -0,0062 mais ou menos 0,0019 nas mesmas unidades. Entre as sub-regiöes, c1 para PP variou de -0,0038 mais ou menos 0,0082 a 0,0155 mais ou menos 0,0064 por dia, enquanto que c2 variou de -0,0178 mais ou menos 0,0041 a 0,0065 mais ou menos 0,0060. Pela baixa magnitude dos c1, evidencia-se a eficiência do conservador nos primeiros oito dias após a coleta. As análises devem ser feitas dentro deste prazo, mas se näo o forem, as equaçöes apresentadas poderäo eventualmente ser utilizadas para correçäo estatística

[Actinic lesions: computed tomography features]. / Lesões actínicas: aspectos à tomografia computadorizada.

The authors emphasize the importance of knowing, understanding and identifying the radiation-induced changes in various body organs by radiologists in order to distinguish them from residual or recurrent malignancies. Computed tomography enables the evaluation of the effects and complications of the radiation therapy, besides other image modalities, and its findings are outlined. The clinical correlation, mainly with the time elapsed between the treatment and the examination is very important to establish the diagnosis.

The response to dietary treatment of patients with chronic post-infectious diarrhea and lactose intolerance.

The response to dietary treatment of patients with chronic post-infectious diarrhea and lactose intolerance was prospectively studied in 29 infants less than 1 year of age. All had gastroenteritis with diarrhea which persisted for more than 3 weeks. In the hospital, diarrhea continued and lactose intolerance was documented while being fed half-strength cow's milk formula. They were given dietary treatment with one of three formulas used for treatment of diarrhea in infancy. Improvement of diarrhea was more frequently achieved with Pregestimil when given as the initial therapy than with the other two formulas. With Pregestimil nine of 10 patients improved whereas only four of nine infants fed Portagen and one of 10 patients initially treated with soy formula improved. Pregestimil was also effective in three of five patients who initially failed to improve with Portagen and in four of eight patients tried with soy formula with or without carbohydrate. Additionally, in the patients who improved, recovery was more rapidly achieved with Pregestimil than with the other two formulas. Formula failures were due to intolerance to glucose polymers in three patients, possibly to protein in seven infants, and an intolerance to all nutrients in five patients. The improvement of the diarrhea was slower in patients who had evidence of colitis in rectal biopsies regardless of the dietary treatment given, but was not correlated with other variables, i.e., etiology of diarrhea, jejunal histology, or duration of diarrhea prior to treatment. However, as a group, the patients who failed to respond to Pregestimil were younger (less than 3 months of age), had more formula changes and associated infections, and were given more antibiotics; they also had more prolonged diarrhea before treatment and more severe jejunal mucosal lesions and jejunal bacterial overgrowth. The data suggests that Pregestimil seems to be the most effective formula for the treatment of infants with chronic post-infectious diarrhea and lactose intolerance.

Rotavirus identification in jejunal juice and stools of acute and chronic forms of infantile gastroenteritis.

1. The present study investigates, by means of a combined enzyme immunoassay for rotaviruses and adenoviruses (EIARA), the occurrence of rotaviruses in stools and jejunal juices from 31 children with acute diarrhea and 18 with chronic diarrhea. 2. Stools from 8 acute cases contained rotaviruses (26%). In two of these cases rotaviruses were also detected in the jejunal juice. 3. In the chronic diarrhea group we identified rotaviruses in the stools of one patient and in the jejunal juice of another. 4. Some of the electropherotypes of the rotaviruses identified showed different patterns of RNA migration. 5. Abnormalities of the jejunal mucosa were characterized in 6 acute rotavirus-positive cases. No morphological or functional abnormalities of the intestinal mucosa were observed in the chronic diarrhea rotavirus-positive cases.

Rotavirus identification in jejunal juice and stools of acute and chronic forms of infantile gastroenteritis

The present study investigates, by means of a combined enzyme immunoassay for rotaviruses and adenoviruses (EIARA), the occurrence of rotaviruses in stools and jejunal juices from 31 children with acute diarrhea and 18 with chronic diarrhea. Stools from 8 acute cases contained rotaviruses (26%). In two of these cases rotaviruses were also detected in the jejunal juice. In the chronic diarrhea group we identified rotaviruses in the stools of one patient and in the jejunal juice of another. Some of the electropherotypes of the rotaviruses identified showed different patterns of RNA migration. Abnormalities of the jejunal mucosa were characterized in 6 acute rotavirus-positive cases. No morphological or functional abnormalities of the intestinal mucosa were observed in the chornic diarrhea rotavirus-positive cases

Genetic regulation of multispecific antibody responsiveness: improvement of "high" and "low" characters.

The five selections carried out in the mouse for high or low antibody responsiveness to various multideterminant immunogens were successful. In all cases the large interline difference was shown to result from the additive effects of several independently segregating loci (polygenic regulation). However, important peculiarities were demonstrated in these original selections concerning either the cellular mechanisms operating or the effect of the selected genes on antibody responses to antigens unrelated with those used for the selection (multi-specific effect). In an attempt to improve and generalize the effect of selection, the 5 high and the 5 low lines were inter-crossed to obtain populations with a balanced proportion of the 5 genomes. These two populations were then submitted to selective breedings in which the phenotypic character was the weighted responses to pluri-antigen immunization. The data obtained in 16 consecutive generations of two selective breedings (general-primary, GP and general-secondary, GS, responses) carried out from these populations are reported. The genetic parameters of the response to GP and GS selections are compared with those obtained in the original selections. The final result of both GP and GS selections demonstrate a marked improvement of the high and low antibody production traits, both quantitatively (interline divergence) and qualitatively (multi-specific effect). The success of GP and GS selections agrees with the concept that distinct groups of genes are preferentially affected by selection according to the nature of the selection antigen and the immunization procedure.

Effect of silica on the genetic regulation of antibody responsiveness.

The high (H) and low (L) antibody responder lines of mice produced by selective breeding are characterized by different modifications in immunocompetent cell potentialities, according to the immunization procedure used for the selection process. In selections I and II, the difference in antibody responsiveness between H and L lines was clearly shown to depend mainly on macrophage function: the more rapid catabolism of antigens in L mice was the main cause of the low antibody production. In contrast, up to now, no difference has been observed between H and L mice of selections III and IV in terms of the macrophage accessory role. The administration of silica particles has a well known impairment effect on macrophage activity. Therefore, the effect of silica injection on the kinetics of antibody responses to selection antigens was compared in H and L mice of the four selections. Silica was given either intravenously or locally in one hind footpad 6 or 24 h before immunization by the same route. Silica treatment consistently improved antibody responsiveness in the L mice of selections I and II, but had no effect in the L mice of selections III and IV. The antibody responses of the H lines of the four selections were not substantially modified by silica injections. Therefore, the silica treatment reduced the interline difference in antibody responses in selections I and II only, by interfering with the expression of the genetic modification of macrophage activity. However, a similar effect was not obtained with other substances known to affect macrophages, including dextran sulphate or carrageenan. The results reported here are in agreement with the above-mentioned statement that the genetic modification of macrophage function plays a major role in the interline difference in selections I and II and is not involved in selections III and IV.

Genetics of antibody responsiveness to bovine serum albumin and rabbit gamma-globulin. I. Genetic analysis of high and low responder lines of mice produced by selective breeding.

The selective breeding for antibody production against bovine serum albumin (BSA) and rabbit gamma-globulin (RGG) induced a large modification in responsiveness in the high (Hv) and low (Lv) responder lines at selection limit. The total response to selection (RT) was 9.0 log2 for BSA and 8.4 log2 for RGG. This gives an interline difference of 500-fold and 337-fold respectively in terms of passive agglutinin titres. For BSA responsiveness, there is, in F1 interline hybrids, an incomplete dominance effect of the low character (-0.41) and a marked maternal effect. Complete dominance effect of high character (1.08) without any maternal effect is observed for responses to RGG. The phenotypical variability of BSA responses in F2 segregants is due 60% to genetic factors and 40% to environmental effects. Such a distribution cannot be achieved for RGG responsiveness. Both responses to BSA and RGG are controlled by the additive effect of several independent loci (polygenic regulation). One of these genes is linked with the H-2 locus. The H-2 linked gene accounts for 29% of the total interline difference for response to BSA and only 11% for response to RGG. Experiments carried out to measure the reciprocal nonspecific effect of BSA and RGG responses failed to give clear-cut results. This important phenomenon will be the subject of the companion article.

Genetics of antibody responsiveness to bovine serum albumin and rabbit gamma-globulin. II. Evidence for a partially common genetic regulation of response to bovine serum albumin and rabbit gamma-globulin.

In order to measure the reciprocal nonspecific effect of the genetic regulation of antibody responsiveness to bovine serum albumin (BSA) and rabbit gamma-globulin (RGG), two independent bidirectional selective breedings for responses to these two antigens were carried out: selection V/BSA and selection V/RGG respectively. The total interline separation at selection limit (RT) was 5.3 log2 for selection V/BSA and 2.6 log2 for selection V/RGG. The sum of these two values (7.9 log2) is similar to the RT in selection V carried out by alternating these two antigens in consecutive generations. In selection V/BSA, the nonspecific effect for responsiveness to RGG was 72%. In selection V/RGG, the nonspecific effect for BSA responsiveness was 135%. The F1 hybrids between homologous lines of selection V/BSA and selection V/RGG presented a larger difference in antibody response to both antigens than their parental lines. This demonstrates an additive effect of the loci controlling the two responses.

Effect of genetic modification of antibody responsiveness on resistance to Toxoplasma gondii infection.

Resistance to Toxoplasma gondii infection was studied in the high (H/f) and low (L/f) antibody responder lines of mice that were selected on the basis of quantitative antibody responsiveness to the flagellar antigen of Salmonella (selection III). No interline difference was observed in resistance to a highly virulent strain of T. gondii. In contrast, H/f mice were much more resistant than L/f mice to a moderately virulent strain of T. gondii: a 5000-fold difference in terms of the 50% lethal dose was found. The degree of resistance in (H/f X L/f)F1 hybrids was intermediate compared with that in parental lines for both mortality and survival time. The antibody titers to Toxoplasma antigens measured during the course of the infection were significantly higher in H/f than in L/f mice. This interline difference was underestimated because parasite multiplication occurs faster in L/f mice, which increases antigenic stimulation. The stronger resistance of H/f mice is probably due to their higher capacity of antibody production in the course of infection.