3,264 research outputs found
The association between sperm aneuploidy and male infertility: Screening, aetiology and possible routes to alternative therapy
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.One in six couples wishing to start a family are infertile. The many causes of infertility include genetic defects that can be single gene, multifactorial or chromosomal (including Y deletions, karyotype abnormalities and gamete aneuploidy). This thesis is concerned with the association between infertility and increased sperm aneuploidy. Specific questions are: should males be screened for sperm aneuploidy before intracytoplasmic sperm injection (ICSI)? Is there a relationship between individual semen parameters and sperm aneuploidy for specific chromosome pairs? What is the role of genome organisation in male gametes and its association with infertility? Whether use of alternative therapy (in this case, traditional Chinese Medicine (TCM)) can be used to improve sperm disomy levels. Statistical analysis of questionnaire data revealed that infertility specialists believed there to be merit in screening sperm aneuploidy levels before ICSI. Evidence is presented for possible chromosome-specific and semen parameter specific mechanisms for sperm aneuploidy as is evidence of genome organisation that may be perturbed in infertile males. Finally, in six males studied, sperm aneuploidy levels improved significantly coincident with TCM. Closer investigation of the biological activity of individual therapeutic herbs and treatment cocktails revealed strong anti-oestrogenic and anti-oxidant properties. This suggests a possible mechanism of action of the herbs and provides the basis from which future placebo controlled clinical trials might continue. Possible criticisms of the work presented here include the unavailability of blood samples from many of the patients (thus preventing karyotype analysis) and the absence of a second control group in our studies on semen parameters. Nevertheless significant steps have been made towards establishing the need for, and the implementation of, a pre-ICSI screening test. Moreover progress has been made towards further understanding the aetiology of sperm aneuploidy and towards the implementation of a new treatment that may, ultimately, augment, or even replace ICSI
DK conjecture for Grassmannian flips
No full textPh.D.We investigate the DK conjecture on derived categories of coherent sheaves stated by Bondal-Orlov and Kawamata: there should be a derived embedding for any flip and in particular a derived equivalence for any flop. Unlike the situations for flops, there are few examples of flips proven to satisfy the DK conjecture except for some toroidal flips.We construct new examples of flips from Grassmannians, called Grassmannian flips, that satisfy the DK conjecture.我們對由彭督-奧爾洛夫（Bondal-Orlov）和川又（Kawamata）提出關於凝聚層的導出範疇相關的DK猜測進行探討：即對於任何翻轉（flip），都應該有導出（範疇的）嵌入，尤其是對於任何平轉 （flop），都應該有導出（範疇的）等價。與平轉（flop）的情況不同，除了一些環形翻轉（toroidal flips） 之外，鮮有反轉的例子證明能夠被證明滿足DK猜想。我們從格拉斯曼簇出發構造了滿足DK猜想的新例子，稱為格拉斯曼翻轉（Grassmannian flips）。Xie, Ying.Thesis Ph.D. Chinese University of Hong Kong 2020.Includes bibliographical references (leaves 84-88).Abstracts also in Chinese.Title from PDF title page (viewed on February 7, 2022)
Inhibition of intestinal cholesterol absorption by surfomer [alpha-olefin maleic acid] affects hepatic cholesterol synthesis and low density lipoprotein transport in hamsters fed a fat-enriched diet
No full textBackground, Surfomer (alpha -olefin maleic acid) reduces intestinal cholesterol absorption. Aims. This study was performed to investigate the effect of surfomer on cholesterol synthesis and low density lipoprotein in hamsters fed a hypercholesterolaemic, lipid-enriched diet. Animals and methods. Male hamsters were fed a diet enriched in cholesterol (0.07%) and saturated fatty acids (coconut oil 20%); the diet was supplemented with 3% surfomer: for 1-4 weeks. Cholesterol synthesis was assessed measuring incorporation of [H-3]water into tissue sterols; low density lipoprotein clearance was determined using a primed-continuous infusion of [I-125]tyramine-cellobiose lipoprotein. Results. Cholesterol synthesis was suppressed after 3 weeks of hyperlipidaemic diet in liver and small bowel (by 88% and 38%, respectively) and was significantly increased by supplementing the fat-enriched diet with surfomer. Low density lipoprotein-cholesterol was increased by 44% after 4 weeks of hyperlipidaemic diet, in parallel with a decrease in hepatic low density lipoprotein clearance rates (48 +/-3 vs 68 +/-7 mul of plasma/h per g of tissue). Concurrent treatment with surfomer for 1, P or 4 weeks prevented the decrease of clearance and maintained normal low density lipoprotein-cholesterol levels at all time points, Conclusions. Surfomer represents a powerful tool to investigate the impact of cholesterol absorption on sterol homeostasis. Furthermore, since surfomer appears to normalize low density lipoprotein transport in hamsters fed a diet comparable to a lipid-rich western-style regimen, this drug may deserve consideration as an adjunct treatment for hypercholesterolaemia in selected patient groups
Mate-guarding in a promiscuous insect : species discrimination influences context-dependent behaviour
No full textFunding: NERC studentshipMating strategy is often informed by social context. However, information on social environment may be sensitive to interference by nearby heterospecifics, a process known as reproductive interference (RI). When heterospecific individuals are present in the environment, failures in species discrimination can lead to sub-optimal mating behaviours, such as misplaced courtship, misplaced rivalry behaviours, or heterospecific copulation attempts. All aspects of mating behaviour that are influenced by social context may be prone to RI, including copulatory behaviours associated with mate-guarding in the presence of possible competitors. Here we investigate the effect of three heterospecifics on the mate-guarding behaviour of male Lygaeus equestris seed bugs. We find that, despite previously reported heterospecific mating harassment amongst these species of lygaeid bug, male L. equestris are able to effectively distinguish rival conspecific males from heterospecifics. Thus, heterospecific mating attempts in this group may reflect selection on males to mate opportunistically, rather than a failure of species discrimination.Peer reviewe
Effects of zinc and copper on male gametophytes off lowering plants
No full textThe Effect of Zinc and Copper on Male Gametophytes of FloweringPlants1) The aim of this study was to investigate the effect of heavy metals in the development of male gametophytes in flowering plants. Several experiments were conducted to find the best germination medium for the maximum percent germination and pollen tube growth of pollen. Temperature was also found to be an important factor influencing pollen tube growth.2) Three plant species were used in this study. They were Kalanchoe fedtschenkoi, Brassica rapa and Hippeastrum. The optimum germination medium for the pollen under study was found to be species-specific. 3) The best in vitro germination medium for the maximum percent germination and pollen tube growth for Kalanctioe fedtsclienl<oi was 10% PEG and 10% sucrose, while for Brassica rapa dwf2 it was 15% PEG and 10% sucrose.4) A 5 C difference of germination temperature was shown to alter pollen tube growth length in two cultivars of Brassica rapa.5) Presence of zinc in the germinating medium led to reductions in both percent pollen germination and pollen tube length growth in Kalanctioe fedtsctienkoi at high concentrations of zinc. In contrast, Bnassica rapa dwf2 showed a greater reduction in percent pollen germination than in pollen tube length. 6) There was a large inhibitory effect of copper on both the percent pollen germination and pollen tube length of Brassica rapa dwf2.7) Cytoplasmic streaming was found to be a useful indicator of the possible toxicity of heavy metals. The movements of granules on the cytoplasm in the pollen tube slowed down when pollen was incubated in germination medium containing heavy metals. Thus this approach provides a sensitive assay for the effects of heavy metals such as zinc and copper upon male gametophytes.8) Brassica rapa dwf2 grown in water culture medium containing heavy metals showed a reduction in in vivo pollen tube growth. Thus, metal uptake by plants from the growing medium does result in metal reaching the male gametophyte and can in turn result in reduction of pollen tube germination and growth, thus potentially markedly affecting reproduction.
Policy Domains and the Speakers' Gender in ParlaMint-DK 4.1
No full textIn this paper, we describe the ParlaMint-DK 4.1 corpus, which consists of the Danish parliament speeches from 2014 to 2022 annotated with 20 general policy domains mapped to the codebook of the Comparative Agendas Project. The policy domains were added to the speeches semiautomatically using the agenda titles under which the speeches occurred. In the paper, we also account for how some of the linguistic annotations of the corpus were improved using the Text Tonsorium and present some of our previous studies on parliament data. We also describe novwl investigations, based on the policy domain annotations in ParlaMint-DK aimed at determining which domains are most frequently addressed in the speeches, and the frequency by which policy areas are debated by female and male politicians during the various governments covered by the corpus
Male circumcision and human papillomavirus infection in men: a systematic review and meta-analysis.
No full textBACKGROUND: We systematically reviewed the evidence for an association between male circumcision and Human Papillomavirus (HPV) infection and genital warts in men. METHODS: PubMed and Embase were searched to 15 September 2010. The measure of effect was the adjusted odds ratio (OR) or rate ratio (RR) when present and the crude estimate otherwise. Random effects meta-analyses were used to calculate summary measures of effect. RESULTS: We identified 23 papers about the association between circumcision and HPV DNA. Circumcised men were less likely to have prevalent genital HPV infection than uncircumcised men (summary OR, 0.57, 95% confidence interval [CI], 0.45-0.71) with between-study heterogeneity (P-heterogeneity = 0.006; I(2) = 50.5%; 19 studies). Similar summary associations were seen in clinical and methodological subgroups. The effect of circumcision was stronger at the glans/corona (OR, 0.47; 95% CI, 0.37-0.60) and urethra (OR, 0.35; 95% CI, 0.12-1.05) compared with sites more distal to the foreskin. There was weak evidence that circumcision was associated with decreased HPV incidence (summary RR, 0.75, 95% CI, 0.57-0.99; 3 studies) and increased HPV clearance (summary RR, 1.33; 95% CI, 0.89-1.98; 3 studies) but no evidence of an association with prevalent genital warts (OR, 0.93, 95% CI, 0.65-1.33; 15 studies). CONCLUSIONS: Several countries are expanding access to voluntary medical male circumcision to reduce HIV prevalence. This could provide additional benefit in reducing HPV prevalence
Policy Domains and the Speakers’ Gender in ParlaMint-DK 4.1
No full textIn this paper, we describe the ParlaMint-DK 4.1 corpus, which consists of the Danish parliament speeches from 2014 to 2022 annotated with 20 general policy domains mapped to the codebook of the Comparative Agendas Project. The policy domains were added to the speeches semi-automatically using the agenda titles under which the speeches occurred. In the paper, we also account for how some of the linguistic annotations of the corpus were improved using the TextTonsorium and present some of our previous studies on parliament data. We also describe novel investigations, based on the policy domain annotations in ParlaMint-DK aimed at determining which domains are most frequently addressed in the speeches and the frequency by which policy areas are debated by female and male politicians during the various governments covered by the corpus
European pea crabs - taxonomy, morphology, and host-ecology (Crustacea: Brachyura: Pinnotheridae)
No full textPinnotherids are small crabs symbiotic to a variety of invertebrates. The European species infest bivalves and sea squirts. Their way of life is parasitic and poses a threat to commercially exploited bivalves. While juveniles of both sexes still look very similar - being agile swimmers and partially free living - a metamorphosis takes place in the female after mating and results in a conspicuous sexual dimorphism. Thereafter, the female settles in its host definitely and is morphologically strongly adapted to the parasitic life phase. A very high reproductive output was demonstrated among several pea crab species infesting bivalves. Despite from that, hardly any information is present in the literature on the pinnotherids’ reproductive biology and the underlying morphology.
Due to their cryptic way of life, the sexual dimorphism, and the different morphotypes of the female, the taxonomy of the Pinnotheridae is a serious challenge. Two widely accepted species are recognized on European coasts: Pinnotheres pisum and Nepinnotheres pinnotheres. Pinnotheres pectunculi was so far only known from the bivalve Glycymeris glycymeris in its type locality Roscoff (France), while Pinnotheres ascidicola and Pinnotheres marioni were described as living exclusively in ascidians without careful comparison with the previously described species. In order to produce standardized comparative descriptions, pea crabs were collected and studied from different hosts and localities in the Northeast Atlantic and in the Mediterranean. Nepinnotheres pinnotheres and Pinnotheres pisum were redescribed with consideration to characters of female and male. According to our morphological analysis, Pinnotheres ascidicola and Pinnotheres marioni are junior synonyms of Nepinnotheres pinnotheres, whereas the status of Pinnotheres pectunculi as a valid species was ascertained. Important characters are the mouthparts, the male gonopods, and especially chelipeds that showed consistent characteristics among different crab stages of both sexes.
Based on our sampling, we estimated the host-range of the European species. Nepinnotheres pinnotheres lives in ascidians and in the pen shell Pinna nobilis. Pinnotheres pisum infests numerous bivalve species - Pinna nobilis included. For Pinnotheres pectunculi novel host records are presented, all from the bivalve family Veneridae. Furthermore, feeding of the Pinnotheres-species was observed. They use a setae comb ventrally on the claw to brush mucus (and the accumulated food particles) from the bivalve gills. Feeding strategies and host-ecology will be thoroughly discussed in consideration to other Pinnotheridae.
We investigated the reproductive systems of European pinnotherids by histological methods, scanning and transmission electron microscopy, and confocal laser scanning microscopy.
The Eubrachyura have internal fertilization: paired vaginas enlarge into storage structures, the spermathecae, which are connected to the ovaries by oviducts. Sperm is stored until the oocytes are mature and transported into the spermathecae, where fertilization takes place. In the investigated pinnotherids, the vagina is of the ‘concave pattern’. Musculature is attached alongside flexible parts of the vagina-wall to control the dimension of its lumen. The genital opening is closed by a muscular mobile operculum.
The spermatheca can be divided into two distinct regions by function and morphology. The ventral part includes the connection with vagina and oviduct and is regarded as the zone where fertilization takes place. It is lined with cuticle except where the oviduct enters the spermatheca by the ‘holocrine transfer tissue’. At ovulation, the oocytes have to pass through this multi-layered glandular epithelium, which has a holocrine mode secretion. The dorsal part of the spermatheca is lined by a highly secretory apocrine glandular epithelium, which was to date only found in fiddler crabs of the genus Uca.
The male internal reproductive system consists of paired testes and corresponding vasa deferentia. The sperm morphology of pinnotherids conforms to other thoracotremes, with slight differences between Nepinnotheres pinnotheres and Pinnotheres pisum. Spermatozoa become enveloped into spermatophores in the secretory proximal vas deferens. The medial vas deferens is strongly enlarged and stores spermatophores embedded in seminal plasma. The distal vas deferens holds tubular appendices, which extend into the ventral cephalothorax and slightly into the pleon. These appendices produce and store vast quantities of seminal plasma. The copulatory system of the Brachyura is formed by paired penes and two pairs of gonopods, which function in sperm transfer. In pinnotherids, the long first gonopods transfers the sperm mass to the female. It holds the ejaculatory canal inside, which opens proximally and distally. The second gonopod is solid, short and conical. During copulation, the penis and the second gonopod are inserted into the base of the tubular first gonopod. The second gonopod functions in the transport of the sperm mass inside the ejaculatory canal towards its distal opening. The specific shape of the second gonopod is strongly adapted for a sealing of the tubular first gonopod with longitudinal cuticle foldings that interlock inside the first gonopod. The presented results are discussed concerning their function in reproduction and in respect of the systematic account.
The role of secretion in sperm transfer, storage and fertilization among the Brachyura is still under debate. It is notable that structure and function of secretion are more complex in pinnotherids and probably more efficient than in other brachyuran crabs, which will be discussed, in view of the parasitic way of life and the high fecundity of pinnotherids
Variation in feather quality traits of Ta6 in male (black) and female (white) barn swallows from six European populations (DK—Denmark, UA—Ukraine, RO—Romania, PL—Poland, IT—Italy, ES—Spain) (mean + SE).
No full text<p>Variation in feather quality traits of Ta6 in male (black) and female (white) barn swallows from six European populations (DK—Denmark, UA—Ukraine, RO—Romania, PL—Poland, IT—Italy, ES—Spain) (mean + SE).</p
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