Página 1 dos resultados de 18717 itens digitais encontrados em 0.020 segundos

A mixed colony of Scaptotrigona depilis and Nannotrigona testaceicornis (Hymenoptera, Apidae, Meliponina)

MENEZES, C.; HRNCIR, M.; KERR, W. E.
Fonte: FUNPEC-EDITORA Publicador: FUNPEC-EDITORA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.74%
We describe a case of a spontaneously established mixed colony of two species of stingless bees. The host colony of Scaptotrigona depilis, an aggressive bee that forms large colonies, was invaded by workers of Nannotrigona testaceicornis, a smaller bee that forms small colonies. The host colony and the invading species colony were maintained in next boxes about 1.5 m apart. The N. testaceicornis colony had been recently divided. Observations were made daily for 10 min, and every two weeks the colony was opened for observations within the nest. Initially the host colony bees repulsed the invading species, but as their numbers built up, they were no longer able to defend the entrance. An estimated 60-90 N. testaceicornis workers lived integrated into the colony of S. depilis for 58 days. During this period, they reconstructed and maintained the entrance tube, changing it to an entrance typical of N. testaceicornis. They also collected food and building material for the host colony. Nannotrigona testaceicornis tolerated transit of S. depilis through the entrance, but did not allow the host species to remain within the tube, though the attacks never resulted in bee mortality. Aggression was limited to biting the wings; when the bees fell to the ground they immediately separated and flew back. There have been very few reports of spontaneously occurring mixed stingless bee colonies. It is difficult to determine what caused the association that we found; probably workers of N. testaceicornis got lost when we split their colony...

Pollen foraging in colonies of Melipona bicolor (Apidae, Meliponini): effects of season, colony size and queen number

HILARIO, S. D.; IMPERATRIZ-FONSECA, V. L.
Fonte: FUNPEC-EDITORA Publicador: FUNPEC-EDITORA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.59%
We evaluated the ratio between the number of pollen foragers and the total number of bees entering colonies of Melipona bicolor, a facultative polygynous species of stingless bees. The variables considered in our analysis were: seasonality, colony size and the number of physogastric queens in each colony. The pollen forager ratios varied significantly between seasons; the ratio was higher in winter than in summer. However, colony size and number of queens per colony had no significant effect. We conclude that seasonal differences in pollen harvest are related to the production of sexuals and to the number of individuals and their body size.; CNPq[140169/2000]; FAPESP[04/15801-0]

Comparação entre o crescimento de Unidades Formadoras de Colônias (UFC) de Staphylococcus spp. e Klebsiella pneumoniae e a sensibilidade destas cepas ao processo de pasteurização lenta; Comparison between the growth of Colony Form Units of Staphylococcus spp. and Klebsiella pneumoniae and the sensibility of these microorganisms to the process of slow pasteurization

Freitas, Gisele Dias de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/02/2008 PT
Relevância na Pesquisa
36.62%
Introdução: O leite pode ser considerado um dos alimentos mais completos por apresentar alto teor de proteínas e sais minerais, porém, também é considerado excelente meio de cultura para microrganismos. Objetivos: Identificar o número de UFC de Staphylococcus spp. e Klebsiella pneumoniae, cultivados isoladamente ou em associação, em leite integral estéril, a 6 oC, 27 oC e 37 oC e descrever a curva de morte térmica, quando submetidas ao processo de pasteurização lenta isoladamente ou em associação. Material e Métodos: Avaliação através da contagem das UFC, do comportamento de Staphylococcus spp. e K. pneumoniae, isoladas de tanque de refrigeração de leite, submetidas a temperaturas que simulam o leite em condições de refrigeração (6 °C), condições ambientais (25 °C) e na temperatura ideal de crescimento de patógenos mesófilos (36°C). Avaliação da sensibilidade de Staphylococcus spp. e K. pneumoniae isoladas e em associações ao processo de pasteurização lenta. Resultados: Na escala 1 de Mac Farland a média de UFC de K. pneumoniae foi maior que a de Staphylococcus spp. A 6 °C as bactérias no leite, isoladas ou em associação crescem na mesma velocidade. A 25 °C a K. pneumoniae cresce mais que o Staphylococcus spp. A 25 °C K. pneumoniae associada ao Staphylococcus spp. cresce mais do que quando encontra-se isolada. A 36 °C K. pneumoniae associada ao Staphylococcus spp. cresce mais do que quando encontra-se isolada e ainda mais que a 25 °C. A pasteurização lenta foi efetiva...

Meta-heurísticas Iterated Local Search, GRASP e Artificial Bee Colony aplicadas ao Job Shop Flexível para minimização do atraso total.; Meta-heuristics Iterated Local Search, GRASP and Artificial Bee Colony applied to Flexible Job Shop minimizing total tardiness.

Melo, Everton Luiz de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 07/02/2014 PT
Relevância na Pesquisa
36.59%
O ambiente de produção abordado neste trabalho é o Job Shop Flexível (JSF), uma generalização do Job Shop (JS). O problema de programação de tarefas, ou jobs, no ambiente JS é classificado por Garey; Johnson e Sethi (1976) como NP-Difícil e o JSF é, no mínimo, tão difícil quanto o JS. O JSF é composto por um conjunto de jobs, cada qual constituído por operações. Cada operação deve ser processada individualmente, sem interrupção, em uma única máquina de um subconjunto de máquinas habilitadas. O principal critério de desempenho considerado é a minimização dos atrasos dos jobs. São apresentados modelos de Programação Linear Inteira Mista (PLIM) para minimizar o atraso total e o instante de término da última operação, o makespan. São propostas novas regras de prioridade dos jobs, além de adaptações de regras da literatura. Tais regras são utilizadas por heurísticas construtivas e são aliadas a estratégias cujo objetivo é explorar características específicas do JSF. Visando aprimorar as soluções inicialmente obtidas, são propostas buscas locais e outros mecanismos de melhoria utilizados no desenvolvimento de três meta-heurísticas de diferentes categorias. Essas meta-heurísticas são: Iterated Local Search (ILS)...

Caste flexibility and variation according to the colony cycle in the swarm-founding wasp, Parachartergus fraternus (Gribodo) (Hymenoptera : Vespidae : Epiponini)

Mateus, S.; Noll, F. B.; Zucchi, R.
Fonte: Kansas Entomological Soc Publicador: Kansas Entomological Soc
Tipo: Artigo de Revista Científica Formato: 470-483
ENG
Relevância na Pesquisa
36.59%
Differences between castes and related aspects in Parachartegus fraternus (Gribodo) have been studied in various stages of the colony cycle. Five colonies from three colony development stages (namely, pre-emergence, worker-producing and male-producing) were analyzed. The main results were: irrespective of colony age, castes were always morphologically indistinguishable; non-inseminated ovary-developed females were found in four colonies; because differences of castes were physiological rather than morphological, castes are evidently post-imaginally determined and this is probably taking place according to the colony conditions. These findings support the occurrence of caste totipotency in Parachartergus fraternus.

Influence of the colony cycle on physiological and morphological caste variation in the perennial neotropical swarm-founding social wasp, Protonectarina sylveirae (Hymenoptera, Vespidae, Epiponini)

Shima, Sulene Noriko; Noll, Fernando Barbosa; Zucchi, Ronaldo
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 449-466
ENG
Relevância na Pesquisa
36.62%
This paper describes the influence of the colony cycle on caste differences in Protonectarina sylveirae. Despite invariably keeping the main aspects of the conspicuous dimorphism between the castes, it is shown that: 1- queen-worker differences varied according to the progress of the colony cycle, 2- queens in pre-emergence colonies were smaller than those in male-producing ones, 3- workers were larger in pre-emergence than in other colony stages, 4- at particular steps of the colony cycle, non-inseminated ovary-developed queens and workers were detected. The size of the spermatheca differed between inseminated and non-inseminated queens with the highest values appearing in those bearing the most developed kind of ovary development. Differences between inseminated and non-inseminated queens were found in tergites III and IV, ovarian development and amount of fatty tissues. Because tergite size relates to gaster size, this character may be an important stimulus for selection of larger queens in the course of the colony cycle.

Impact of nutritional conditions on colony morphology variants isolated from P. aeruginosa and S. aureus biofilms

Sousa, A. M. M.; Machado, Idalina; Pereira, Maria Olívia
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2011 ENG
Relevância na Pesquisa
36.73%
In natural habitats, microorganisms are challenged all the time due to stress conditions imposed by the surrounding environment. To adapt to these environmental changes, bacteria alter their physiological and genetic traits. This adaptive behavior may be achieved by phenotype switching. This process consists in a reversible switch of phenotypes, as a mechanism ON/OFF, which occurs at high frequencies than spontaneous mutations. Colony morphology variation is the macroscopic feature of the phenotypic switching. Colony variation may have serious impact on bacterial virulence and antimicrobial resistance potentiating its ability to cause disease. Some colony variants are strongly associated to antibiotic resistance due to their presence in chronic infections despite antibiotic therapy. In cystic fibrosis, the switch of P. aeruginosa from non-mucoid to mucoid morphotype, which overproduce alginate, is a crucial stage to the establishment of this recalcitrant disease. Small colony variants (SCV) are other well-known resistant morphotype. These variants exhibited small size because its slow growth rate, pigmentation, haemolysis, reduced range of carbohydrate utilization and higher resistance to aminoglycosides antibiotics and cell-wall inhibitors. It has been growing the number of studies related with phenotypic switching and colony morphology characterization. However...

Detection of resistant mutants within Pseudomonas aeruginosa colony morphology variants in lung cystic fibrosis environment

Sousa, Ana Margarida; Pereira, Maria Olívia
Fonte: ICAR 2012 Publicador: ICAR 2012
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
Relevância na Pesquisa
36.78%
Bacterial infections caused mainly by P. aeruginosa are typical of cystic fibrosis (CF) lung disease. Despite the long and aggressive antibiotic therapy, CF patients still died because of these chronic infections. The deprived bacterial eradication is mainly due to several strategies adopted by bacteria to achieve CF airways adaptation and tolerance to antibiotics. Biofilm formation and phenotypic switching are among the most relevant adaptive biological processes. Triggering those processes bacteria have the potential to better survive to CF conditions and antibiotics action. Phenotypic switching provides a source of microbial diversity through switch between two phenotypic states, analogue to a mechanism ON/OFF, without the fitness costs of irreversible mutations. This interchange of states, visible by differential colony morphology, can have serious impact on bacterial virulence, antimicrobial resistance and persistence. The present work aims to investigate the specific colony variants-forming bacteria responsible by typical CF chronic infections. Through isolation and deep characterization of those colony variants, including discriminatory antibiotic susceptibility profiles and virulence characterization, it is intended to determine the mechanisms underlying the inefficiency of antimicrobial therapies of airway CF. P. aeruginosa strains (collection and clinical isolated) and LB medium were used to simulate airway CF infections. Clonal diversification of P. aeruginosa was checked after 24...

The role of antimicrobial stress on Pseudomonas aeruginosa colony morphology diversity, tolerance and virulence

Sousa, A. M.; Loureiro, J.; Machado, Idalina; Pereira, Maria Olívia
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
Relevância na Pesquisa
36.76%
In natural environments, as well as in infections, bacteria faced several stresses like starvation, heat exposure, antimicrobials and host defense after entry in human body. The ability to quickly adapt to a new environment is critical to bacteria and the underlying mechanisms are not fully understood. One of the strategies adopted by bacteria is a high frequency of phenotype switching by a mechanism called phase variation. A sign of these bacterial changes is the altered colony morphology on solid media. Several colony morphologies have been isolated from clinical strains, being the best-studied the small colony variants, the rugose small colony variants and the mucoid phenotype. It was aimed to study the prevalence and diversity of colony morphologies from planktonic and sessile P. aeruginosa (Pa) ATCC, chemically stressed, and to compare with the ones developed by a P. aeruginosa isolated from a medical device (Pa I). Pa is one of the most important opportunistic pathogen commonly found in clinical arena being often responsible for acute and chronic infections. Planktonic and sessile Pa and Pa I were in vitro stressed by continuous exposure to benzalkonium chloride (BZK) and peroxide hydrogen and by attack with the same products. The stressed bacteria were collected...

Improvements on colony morphology identification towards bacterial profiling

Sousa, A. M.; Machado, Idalina; Nicolau, Ana; Pereira, Maria Olívia
Fonte: Elsevier; Elsevier BV Publicador: Elsevier; Elsevier BV
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
36.78%
Colony morphology may be an indicator of phenotypic variation, this being an important adaptive process adopted by bacteria to overcome environmental stressors. Furthermore, alterations in colony traits may reflect increased virulence and antimicrobial resistance. Despite the potential relevance of using colony morphological traits, the influence of experimental conditions on colony morphogenesis has been scarcely studied in detail. This study aims to clear and systematically at demonstrating the impact of some variables, such as colony growth time, plate colony density, culture medium, planktonic or biofilm mode of growth and strains genetic background, on bacterial colony morphology features using two P. aeruginosa strains. Results, based on 5-replicate experiments, demonstrated that all variables influenced colony morphogenesis and 18 different morphotypes were identified, showing different sizes, forms, colours, textures and margins. Colony growth time and composition of the medium were the variables that caused the highest impact on colony differentiation both derived from planktonic and biofilm cultures. Colony morphology characterization before 45 h of incubation was considered inadequate and TSA, a non-selective medium, provided more colony diversity in contrast to P. aeruginosa selective media. In conclusion...

MorphoCol : an ontology-based knowledgebase for the characterisation of clinically significant bacterial colony morphologies

Sousa, A. M.; Pereira, Maria Olívia; Lourenço, Anália
Fonte: Elsevier Inc. Publicador: Elsevier Inc.
Tipo: Artigo de Revista Científica
Publicado em //2015 ENG
Relevância na Pesquisa
36.7%
Background One of the major concerns of the biomedical community is the increasing prevalence of antimicrobial resistant microorganisms. Recent findings show that the diversification of colony morphology may be indicative of the expression of virulence factors and increased resistance to antibiotic therapeutics. To transform these findings, and upcoming results, into a valuable clinical decision making tool, colony morphology characterisation should be standardised. Notably, it is important to establish the minimum experimental information necessary to contextualise the environment that originated the colony morphology, and describe the main morphological features associated unambiguously. Results This paper presents MorphoCol, a new ontology-based tool for the standardised, consistent and machine-interpretable description of the morphology of colonies formed by human pathogenic bacteria. The Colony Morphology Ontology (CMO) is the first controlled vocabulary addressing the specificities of the morphology of clinically significant bacteria, whereas the MorphoCol publicly Web-accessible knowledgebase is an end-user means to search and compare CMO annotated colony morphotypes. Its ultimate aim is to help correlate the morphological alterations manifested by colony-forming bacteria during infection with their response to the antimicrobial treatments administered. Conclusions MorphoCol is the first tool to address bacterial colony morphotyping systematically and deliver a free of charge resource to the community. Hopefully...

How to increase the population of a Phlebotomus perniciosus (Diptera: Psychodidae) colony: a new method

Alarcón-Elbal,Pedro María; Montoliu,Begoña García; Pinal,Rocío; Delacour-Estrella,Sarah; Ruiz-Arrondo,Ignacio; Peribáñez,Miguel Ángel; Blas,Ignacio De; Molina,Ricardo; Castillo,Juan Antonio; Diéguez-Fernández,Lorenzo; Lucientes,Javier
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
Relevância na Pesquisa
36.59%
The sandfly Phlebotomus perniciosus is the most widespread vector of Leishmania infantum in Spain. Laboratory colonisation represents the most feasible source of information on the biology of these insects, but in conducting any study, the density of individuals in the colony may drop to such an extent that it is sometimes difficult to recover the initial population levels. A new technique was tested for the recovery of sandfly eggs in three different colonies; the recovery rate was studied by comparing the standard method of mass rearing with this new method of colony management. The results demonstrate a mean increase of 18.4% in adult production, a growth in colony productivity that justifies the inclusion of this process in the routine maintenance of any colony of sandflies.

Colony cycle of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae)

Torres,Viviana O.; Montagna,Thiago S.; Fernandes,Wedson D.; Antonialli-Junior,William F.
Fonte: Sociedade Brasileira De Entomologia Publicador: Sociedade Brasileira De Entomologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 EN
Relevância na Pesquisa
36.59%
Colony cycle of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae). This study describes some aspects of the colony cycle of the Neotropical social wasp Mischocyttarus consimilis, from data obtained under field conditions. Our results showed that the colony cycle in M. consimilis is annual and asynchronous in relation to the months of the year. The colonies remained active for approximately eight months. Most of the abandonments were associated with natural causes, and were most frequent in the pre-emergence stage. The nests were constructed preferentially in man-made structures, especially in sites protected from direct sunlight and rain. Colony foundation was either by haplometrosis or pleometrosis, being the first form predominant.

Use of RAPD, enzyme activity staining, and colony size to differentiate phytopathogenic Fuzarium Oxysporum isolates from Iran

Motallebi,Mostafa; Zamani,Mohammad Reza; Jazayeri,Omid; Harighi,Mohammad Javad
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2002 EN
Relevância na Pesquisa
36.62%
Fusarium oxysporum is a common soilborn plant pathogen with a worldwide distribution. Fusarium yellows disease of chickpea (Cicer arientinum) caused by F.oxysporum is one of the most destructive soilborn disease which is a major production constraint in chickpea-growing regions of Iran. Three laboratory methods "amplification of genomic DNA using random primers, enzyme activity staining, and colony size determination" have been used to discriminate between highly virulent (HV) and weakly virulent (WV) isolates of F. oxysporum. On the basis of colony size (a traditional morphological method) and the ability of isolates to produce pectic enzymes, five HV isolates were differentiated from three WV isolates. The HV isolates formed large colony (ranging from 10.1 to 12.6 mm in diameter) and showed the same enzyme pattern,while the WV isolates produced small colony (ranging from 5.8 to 7.8 mm in diameter) and had not detectable enzyme activity in the stained overlaying gel. Twelve arbitrary 10-mer primers were tested on these 8 isolates of F. oxysporum by Polymerase Chain Reaction (PCR). Cluster analysis of the data from the DNA amplification by Random Amplified Polymorphic DNA (RAPD), differentiated HV from WV isolates. The results obtained from RAPD test confirmed the classification of these eight isolates based on pathogenicity test...

Seasonal and colony differences in the foraging ecology of New Zealand fur seals (Arctocephalus forsteri).

Baylis, Alastair Martin Mitri
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
36.65%
The New Zealand fur seal (Arctocephalus forsteri) is the most abundant fur seal species in the Australian-New Zealand region. Approximately 85 % of Australia’s population of New Zealand fur seals reside in the state of South Australia. As a result of their abundance and size, it has been estimated that the New Zealand fur seal population in South Australia consumes the greatest biomass of resources of all marine mammal and seabird species. However, despite the importance of New Zealand fur seals as top predators, our understanding of their foraging ecology in South Australia is limited. In order to better understand the habitat utilized and the diet of New Zealand fur seals, this study explores the foraging ecology of lactating seals from four primary colonies in South Australia, which account for ~ 78 % of the Australian population. These colonies are Cape Gantheaume (36о04’S, 137о27’E) and Cape du Couedic (36о03’S, 136о42’E) on Kangaroo Island; North Neptune Island (35о13’S, 136о03’E) and Liguanea Island (34о59’S, 135о37’E). I start this study by assessing the seasonal variation in foraging location and dive behaviour of lactating New Zealand fur seals from Cape Gantheaume. 18 seals were fitted with satellite transmitters and time depth recorders (TDRs). The presence of thermoclines (derived from TDRs)...

Colony-specific foraging areas of lactating New Zealand fur seals

Baylis, A.; Page, B.; Goldsworthy, S.
Fonte: Inter-research Publicador: Inter-research
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
36.62%
During 2005 and 2006, 21 lactating New Zealand fur seals Arctocephalus forsteri were tracked from 4 breeding colonies in southern Australia. The distance between colonies ranged between 46 and 207 km. In total, 101 foraging trips were recorded (2 to 19 trips ind.–1). Seals initiated foraging trips on a colony-specific bearing (Cape Gantheaume 141 ± 34°, Cape du Couedic 188 ± 12°, North Neptune Island 204 ± 12° and Liguanea Island 235 ± 19°). During autumn, seals from Cape du Couedic, North Neptune Island and Liguanea Island predominantly targeted distant oceanic waters associated with the subtropical front (STF), while seals from Cape Gantheaume targeted shelf waters associated with a seasonal coastal upwelling, the Bonney upwelling. The distance of each colony from the STF (based on the preferred colony bearing) or the Bonney upwelling in the case of Cape Gantheaume was correlated with the maximum straight-line distances travelled (Cape Gantheaume 119 ± 57 km, Cape du Couedic 433 ± 99 km, North Neptune Island 564 ± 97 km and Liguanea Island 792 ± 82 km). The organisation of colony-specific foraging grounds appears to be influenced by the proximity of colonies to predictable local upwelling features, as well as distant oceanic frontal zones. Knowledge of whether New Zealand fur seals utilise colony-specific foraging grounds may be important in predicting and identifying critical habitats and understanding whether management requirements are likely to vary between different colonies.; Alastair Martin Mitri Baylis...

The influence of stored pollen and of colony size on the brood rearing of honeybees

Allen, M.D.; Jeffree, E.P.
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Journal Article-postprint
EN; ENGLISH
Relevância na Pesquisa
36.59%
Four hundred and thirty records of the numbers of bees in honeybee colonies and of the amounts of brood and pollen present have been kept during various months of the years 1945-53, and the data have been used to calculate total and partial regression coefficients showing the influence of stored pollen and of colony size on brood rearing throughout the year. It was found that pollen storage and colony size were correlated but that, even allowing for this, colony size and pollen both independently influenced brood rearing. The annual distribution of the total regression coefficients of brood on pollen was somewhat similar to the brood curve itself, rising from a minimum in October and November to a maximum in midsummer, while the partial regression coefficients showed less clearly marked but similar features. Both total and partial regression coefficients showing the influence of colony size on the amount of brood reared were also at a minimum in October and November, but reached their peaks in May. The quantities of brood present in these colonies at Aberdeen, Scotland, followed a pattern similar to that given by Nolan for colonies near Washington, D.C.

Colony strength and queen replacement in Melipona marginata (Apidae: Meliponini)

Kleinert,A. de M. P.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2005 EN
Relevância na Pesquisa
36.62%
Physogastric queens of Melipona marginata were removed from their colonies in order to verify the acceptance of a new queen by workers. Colony strength was evaluated according to queen oviposition rate and comb diameters. Replacement was observed seven times. Its occurrence and speed related positively to colony strength, independently of queen's age. In weak colonies, queen replacement was observed only once, following colony population increase that occurred after introduction of combs from another colony. Worker oviposition after queen removal was observed three times: in a strong colony with virgin queens and males, and in two of the weak colonies. In the first two or three days of new queen oviposition, during which most of the eggs were eaten by the queen, worker oviposition preceded almost all provisioning and oviposition processes (POPs). After this period, worker oviposition decreased until it reached around 25% of the POPs. Daily oviposition rate of young queens decreased or was even interrupted by hatching of their first brood.

Differential fiu–lacZ fusion regulation linked to Escherichia coli colony development

Newman, Dina; Shapiro, James
Fonte: Blackwell: Molecular Microbiology Publicador: Blackwell: Molecular Microbiology
Tipo: Artigo de Revista Científica Formato: 29143 bytes; application/pdf
EN_US
Relevância na Pesquisa
36.62%
Colonies of strains carrying a stable λplacMu15 translational fusion displayed sharply defined intense staining at the centre on Xgal medium. The fusion was in fiu (ferric ion uptake), encoding an iron-regulated outer membrane protein (IROMP) controlled via four overlapping ferric uptake regulator (Fur) boxes in the σ70 promoter region. Fiu–LacZ was synthesized in low amounts (< 1% of a transcriptional fiu::lacZ+ fusion), localized to membranes, and underwent processing from a large protein to one that co-migrated with native β-galactosidase. Intact cells synthesizing Fiu–LacZ often displayed greater enzymatic activity than permeabilized cells. The colony centre was insensitive to iron regulation observed in liquid cultures and at the colony edge. Within colonies grown on 36 μM iron citrate medium, fiu'–'lacZ protein fusion strains displayed 60-fold higher β-galactosidase activity in the centre, and transcriptional fiu::lacZ+ fusion strains displayed a 10-fold centre/edge difference. On medium without added iron citrate, the centre/edge difference collapsed to < 2.2-fold for both translational and transcriptional fusions because activity at the edge was derepressed. Iron-insensitive fiu'–'lacZ expression in the colony centre occurred during a 6–18 h time window at the start of colony morphogenesis...

Proliferation of dendritic cell progenitors in long term culture is not dependent on granulocyte macrophage-colony stimulating factor

Wilson, Heather; Ni, Keping; O'Neill, Helen
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.62%
A unique long term culture (LTC) system has been developed which supports the production of dendritic cells (DC). Cell production is dependent on a stromal cell layer derived from murine spleen. This LTC system produces a high turnover of non-adherent cells that express DC morphology, cell- surface markers, and antigen-presenting capacity. Objective The long term production of these cells suggests that the LTC system supports hemopoiesis. It was of interest to examine the number and nature of hemopoietic progenitors present in LTC. Materials and Methods A combination of approaches, including FACS analysis, spleen colony-forming unit assays, and in vitro colony assays were undertaken. Results Pluripotent haemopoietic stem cells are not detectable among the non-adherent cell population produced in LTC. Instead, LTC support a replicating c-kit+ progenitor population, which generates only dendritic-like colonies in in vitro colony assays. In addition, this population does not respond to combinations of growth factors thought to stimulate DC proliferation, including granulocyte macrophage- colony stimulating factor (GM-CSF) and Flt3L. Production of DC occurs only in the presence of LTC-derived culture supernatant or a confluent stromal cell layer. Conclusions These results suggest that LTC contain a dendritic progenitor that is dependent upon the stromal cell network for proliferation and differentiation. The development of only DC within LTC allows easy collection of cells for experimentation. This...