130 research outputs found
Segregation distortion in Drosophila melanogaster: Genetic and molecular analyses
No full textThe Segregation Distorter (SD) complex in the centromeric region of chromosome 2 in Drosophila melanogaster is responsible for a naturally occurring and strong system of male meiotic drive. Earlier recombinational dissection and deletional analysis showed that the SD complex resolves into three major loci: the euchromatic Sd, or Segregation distorter gene at the base of the left arm of the chromosome (2L), and two heterochromatic genes: E(SD), the Enhancer of SD, and Rsp, the Responder, in the center of the left arm and the right arm (2R), respectively. Rsp exists in the major allelic forms, Rsp(s), for sensitive, and Rsp(i), for insensitive. Males that are heterozygous for an SD chromosome (SdE(SD)Rsp(i)) and a sensitive SD+ homologue (Sd+ E(SD)+ Rsp(s)) transmit predominantly or even exclusively the SD-bearing chromosome to the progeny. The distortion of the segregation ratio is traceable to failure in chromatin condensation and maturation of those spermatids that receive the Rsp(s) homologue during meiosis. Characterization of the properties of null alleles of Sd, E(SD), and Rsp that were generated by delection determined the precise cytological locations of the components and established the functional relationship of each to its wild-type counterpart, suggesting a model whereby a deleterious action of Sd, along with E(SD), on the Rsp(s) target sets in motion the events culminating in sperm dysfunction. Further genetic analysis of E(SD), a gene required for full expression of drive, showed that E(SD) in two doses can cause significant distortion even in the absence of Sd. This distortion is suppressible by a suppressor of SD action. Thus, E(SD) is more than a simple modifier of Sd; rather, it is an effector locus that, like Sd, can act at the Rsp(s) target. Cloning and molecular analysis of the Sd locus reveal that the alteration uniquely associated with Sd is a 5-kb tandem duplication within the polytene band 37D5, which is where Sd is known to map. The Sd-associated duplication appears to be part of a large gene about 100 kb in size. A 4.2-kb SD-specific transcript has been identified, and analyses of the cDNAs indicate a complex transcription pattern. Since Responder plays such a key role in segregation distortion, recent progress in analyzing this locus has been exciting. Studies of Rsp at the genetic, cytogenetic, and molecular levels have been mutually reinforcing and consistent in demonstrating that Rsp is an extended locus that is (1) subdivisible and (2) associated with a 120-bp repeated sequence of DNA that is rich in adenine-thymine pairs and whose copy number is correlated with the degree of sensitivity. In an exceptional situation, there are certain Sd Rsp(i)/Sd+ Rsp(s) males carrying particular modifiers in which the Rsp(i) chromosome can be transmitted at frequencies of less than 0.50 relative to the Rsp(s) chromosome, suggesting that the genetics of segregation ratios may involve even further complexities, which need to be unraveled
Making use of expertise: A qualitative analysis of the experience of breastfeeding support for first time mothers
No full textThere is now a body of research evaluating breastfeeding interventions and exploring mothers’ and health professionals’ views on effective and ineffective breastfeeding support. However, this literature leaves relatively unexplored a number of questions about how breastfeeding women experience and make sense of their relationships with those trained to provide breastfeeding support. The present study collected qualitative data from 22 breastfeeding first-time mothers in the UK on their experiences of, and orientation towards, relationships with maternity care professionals and other breastfeeding advisors. The data were obtained from interviews and audio-diaries at two time points during the first five weeks post-partum. We discuss a key theme within the data of ‘Making use of expertise’ and three subthemes which capture the way in which the women’s orientation towards those assumed to have breastfeeding expertise varied according to whether the women (i) adopted a position of consulting experts versus one of deferring to feeding authorities (ii) experienced difficulty interpreting their own and their baby’s bodies and (iii) experienced the expertise of health workers as empowering or disempowering. Although sometimes mothers felt empowered by aligning themselves with the scientific approach and ‘normalising gaze’ of healthcare professionals, at other times this gaze could be experienced as objectifying and diminishing. The merits and limitations of a person-centred approach to breastfeeding support are discussed in relation to using breastfeeding expertise in an empowering rather than disempowering way
Evaluating the audio-diary method in qualitative research
No full textPurpose
Audio-diary methods are under-utilised in contemporary qualitative research. In this paper we discuss participants and researchers’ experiences of using audio-diaries alongside semi-structured interviews to explore breastfeeding experiences in a short-term longitudinal study with 22 first-time mothers.
Design/methodology/approach
We provide a qualitative content analysis of the participants’ feedback about their experiences of the audio-diary method and supplement this with the perspectives of the research team based on fieldwork notes, memos and team discussions. We pay particular attention to the ways in which the data attained from diaries compared with those from the interviews.
Findings
The diaries produced were heterogeneous in terms of data length and quality. Participants’ experiences with the method were varied. Some found the process therapeutic and useful for reflecting upon the development of breastfeeding skills whilst negative aspects related to lack of mobility, self-consciousness and concerns about confidentiality. Researchers were positive about the audio-diary method but raised certain ethical, epistemological and methodological concerns. These include debates around the use of prompts, appropriate support for participants and the potential of the method to influence the behaviour under scrutiny. Interview and diary accounts contrasted and complemented in ways which typically enriched data analysis.
Practical implications
The authors conclude that audio-diaries are a flexible and useful tool for qualitative research especially within critical realist and phenomenological paradigms
Originality/value
This appears to be the first paper to evaluate both participants and researchers’ experiences of using audio-diaries in a detailed and systematic fashio
Comprehensive comparative genomics reveals over 50 phyla of free living and pathogenic bacteria are associated with diverse members of the amoebozoa
No full textThe Amoebozoa, a group containing predominantly amoeboid unicellular protists has been shown to play an important ecological role in controlling environmental bacteria. Amoebozoans not only graze bacteria but also serve as a safe niche for bacterial replication and harbor endosymbiotic bacteria including dangerous human pathogens. Despite their importance, only a few lineages of Amoebozoa have been studied in this regard. In this research, we conducted a comprehensive genomic and transcriptomic study with expansive taxon sampling by including representatives from the three known clades of the Amoebozoa. We used culture independent whole culture and single cell genomics/transcriptomics to investigate the association of bacteria with diverse amoebozoans. Relative to current published evidence, we recovered the largest number of bacterial phyla (64) and human pathogen genera (51) associated with the Amoebozoa. Using single cell genomics/transcriptomics we were able to determine up to 24 potential endosymbiotic bacterial phyla, some potentially endosymbionts. This includes the majority of multi-drug resistant pathogens designated as major public health threats. Our study demonstrates amoebozoans are associated with many more phylogenetically diverse bacterial phyla than previously recognized. It also shows that all amoebozoans are capable of harboring far more dangerous human pathogens than presently documented, making them of primal public health concern
The role of the transposable element hobo in the origin of endemic inversions in wild populations of Drosophila melanogaster
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Selected case studies in modeling and simulation applied to environmentally conscious design and manufacturing
No full textThe Process Modeling System (ProMoS) is an object-oriented, mass balance-based, discrete-event manufacturing simulation framework. Analytical capabilities within ProMoS include complete mass balance specifications and facility profiles for materials consumption, resource utilization and worker exposure. ProMoS software has been utilized in the design of several processing facilities including a Printed Wiring Board (PWB) Manufacturing plant and Department of Energy (DOE) nuclear material processing plants. ProMoS was employed to optimize facility design with respect to production/storage capacity, transportation/shipping constraints, waste generation, cost, worker safety and overall environmental consequences. In addition, ProMoS has been employed in the operational characterization of processing facilities at Los Alamos National Laboratory. The environments used to develop these assessment tools will be discussed in addition to a review of initial implementation results
It should be the most natural thing in the world: exploring first-time mothers' breastfeeding difficulties in the UK using audio-diaries and interviews
No full textBreastfeeding is a practice which is promoted and scrutinized in the UK and internationally. In this paper, we use interpretative phenomenological analysis to explore the experiences of eight British first-time mothers who struggled with breastfeeding in the early post-partum period. Participants kept audio-diary accounts of their infant feeding experiences across a 7-day period immediately following the birth of their infant and took part in related semi-structured interviews a few days after completion of the diary. The overarching theme identified was of a tension between the participants' lived, embodied experience of struggling to breastfeed and the cultural construction of breastfeeding as ‘natural’ and trouble-free. Participants reported particular difficulties interpreting the pain they experienced during feeds and their emerging maternal identities were threatened, often fluctuating considerably from feed to feed. We discuss some of the implications for breastfeeding promotion and argue for greater awareness and understanding of breastfeeding difficulties so that breastfeeding women are less likely to interpret these as a personal shortcoming in a manner which disempowers them. We also advocate the need to address proximal and distal influences around the breastfeeding dyad and, in particular, to consider the broader cultural context in the UK where breastfeeding is routinely promoted yet often constructed as a shameful act if performed in the public arena
The impact of viral mutations on recognition by SARS-CoV-2 specific T cells
No full textWe identify amino acid variants within dominant SARS-CoV-2 T cell epitopes by interrogating global sequence data. Several variants within nucleocapsid and ORF3a epitopes have arisen independently in multiple lineages and result in loss of recognition by epitope-specific T cells assessed by IFN-γ and cytotoxic killing assays. Complete loss of T cell responsiveness was seen due to Q213K in the A∗01:01-restricted CD8+ ORF3a epitope FTSDYYQLY207-215; due to P13L, P13S, and P13T in the B∗27:05-restricted CD8+ nucleocapsid epitope QRNAPRITF9-17; and due to T362I and P365S in the A∗03:01/A∗11:01-restricted CD8+ nucleocapsid epitope KTFPPTEPK361-369. CD8+ T cell lines unable to recognize variant epitopes have diverse T cell receptor repertoires. These data demonstrate the potential for T cell evasion and highlight the need for ongoing surveillance for variants capable of escaping T cell as well as humoral immunity
Expressing yourself: A feminist analysis of talk around expressing breast milk
No full textRecent feminist analyses, particularly from those working within a poststructuralist framework, have highlighted a number of historically located and contradictory socio-cultural constructions and practices which women are faced with when negotiating infant feeding, especially breastfeeding, within contemporary western contexts. However, there has been little explicit analysis of the practice of expressing breast milk. The aim of this article is to explore the embodied practice of expressing breast milk. This is done by analysing, from a feminist poststructuralist perspective, discourse surrounding expressing breast milk in sixteen first time mothers’ accounts of early infant feeding. Participants were recruited from a hospital in the South Midlands of England. The data are drawn from the first phase of a larger longitudinal study, during which mothers kept an audio diary about their breastfeeding experiences for seven days following discharge from hospital, and then took part in a follow-up interview. Key themes identified are expressing breast milk as (i) a way of managing pain whilst still feeding breast milk; (ii) a solution to the inefficiencies of the maternal body; (iii) enhancing or disrupting the ‘bonding process’; (iv) a way of managing feeding in public; and (v) a way to negotiate some independence and manage the demands of breastfeeding. Links between these and broader historical and socio-cultural constructions and practices are discussed. This analysis expands current feminist theorising around how women actively create the ‘good maternal body’. As constructed by the participants, expressing breast milk appears to be largely a way of aligning subjectivity with cultural ideologies of motherhood. Moreover, breastfeeding discourses and practices available to mothers are not limitless and processes of power restrict the possibilities for women in relation to infant feeding
'They only smoke in the house when I'm not in' : understanding the limited effectiveness of a smoke-free homes intervention
No full textAcknowledgements We would like to thank all the mothers who participated, the Lanarkshire First Steps Programme workers and Ms C Briffa-Watt. Funding This work was supported by the Scottish Government Chief Scientist Office (CZH_4_983).Peer reviewe
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