bluuebunny/crossref_metadata_2025_split huggingface dataset:
Models for mapping quantitative trait loci (QTL) in progeny of non-inbred parents and their behaviour in presence of distorted segregation ratios
Authors: Schäfer-Pregl R. , Salamini F. , Gebhardt C. 
Published: September 2009

SummaryIn plants, models for mapping quantitative trait loci (QTL) based on flanking markers have been mainly developed for progenies of inbred lines. We propose twoflanking marker models for QTL mapping in F1progenies of non-inbred parents. The first is based on the segregation of four different scorable alleles at a marker locus (the four-allele model) and the second (the commonallele model) on one scorable allele per marker locus segregating in both parents. These models are suitable for the majority of the allelic configurations which may occur in crosses between heterozygous parents. For both cases, when four scorable or one common-allele per marker locus segregate, additional algorithms were developed to estimate the recombination frequency between two marker loci. Tests carried out with simulated populations of various sizes indicate that the models provide a good estimate of QTL genotypic means and of recombination frequencies between flanking markers and between the marker loci and the QTL.The estimates of QTL genotypic means have a higher precision than the estimates of recombination frequencies. The four-allele model shows a higher ability to detect QTLs than the common-allele model. If segregation ratios are distorted, the power of both models and the precision of the estimates of recombination frequencies are reduced, whereas the accuracy of estimates of QTL genotype means is not affected by distorted segregation ratios. The power of the common-allele model is substantially reduced if QTL genotypic means depend on additive allelic interactions, whereas the four-allele model is less affected by the non-additive behaviour of QTL alleles.
Natural Repressors of P-induced hybrid dysgenesis inDrosophila melanogaster: a model for repressor evolution
Authors: Corish P. , Black D. M. , Featherston D. W. , Merriam J. , Dover G. A. 
Published: September 2009

SummaryType I repressors control P element transposition and comprise full length elements and elements with small 3′ deletions in the final exon. Using a sensitive assay for measuring the strength of repression of P element transposition in somatic and germline tissues, we have isolated and characterized a naturally occurring type I repressor element from a Q population ofDrosophila melanogaster. We demonstrate that the almost complete repression of transposition in this population is a mixture of KP elements with intermediate levels of repression, and the strong contribution of a single 2·6 kb P element deletion derivative, which we call SR (Strong Repressor). A deletion in the final intron of SR allows for the constitutive production of a putative 75 kDa repressor protein in germline tissues in addition to the production of the 66 kDa repressor in the soma, which would result in a biparental mode of inheritance of repression. Basedon the four observed classes of natural Q populations, we propose a model in which populations containing SR-like elements, capable of producing strong type I repressor constitutively, have a selective advantage over populations which rely either on maternally transmitted P cytotype or on KPinduced weak levels of repression. Such populations may subsequently spread and constitute an evolutionary stable strategy for the repression of hybrid dysgenesis inDrosophila melanogaster.
A quantitative test for developmental neutrality of a transgenic lineage marker in mouse chimaeras
Authors: West John D. , Keighren Margaret A. , Flockhart Jean H. 
Published: September 2009

SummaryThe mouse transgene, provisionally designated TgN(Hbb-b1)83Clo, was produced by Dr C. Lo by pronuclear injection of the cloned ß-major globin gene and comprises a highly reiterated sequence that is readily detected by DNAin situhybridization on histological sections. This fulfils many of the requirements of an ideal genetic cell marker and has been widely used for lineage studies with mouse chimaeras. However, it is not known whether it causes cell selection or influences developmental processes, such as cell mixing, in chimaeric tissues. In the present study, nontransgenic genetic markers (electrophoretic polymorphisms of glucose phosphate isomerase and differences in eye pigmentation) revealed no significant effect of the presence of hemizygous transgenic cells on the overall composition, size or gross morphology of 12½ d chimaeric foetuses, placentas or extraembryonic membranes. Also, a previously described maternal genetic effect on the composition of chimaeric tissues occurred in the presence or absence of the transgene. These tests have demonstrated that hemizygous cells are not at a significant selective disadvantage, when incorporated into mouse aggregationchimaeras with non-transgenic cells. Further studies are needed to test whether homozygous transgenic cells are also selectively neutral and to test whether hemizygous or homozygous transgenic cells influence developmental processes, such as cell mixing, that were not tested.
Behavioural changes as a correlated response to selection
Authors: Holmes Ingrid S. , Hastings Ian M. 
Published: September 2009

SummaryLines of mice have been selected for up to 50 generations on the following traits: high body weight, low body weight, high fat content or low fat content. The lines selected for high or low body weight differ by a factor of 2·5 and those selected for high or low fat content differ by a factor of five, both traits measured in 10 week old males. A set of behavioural traits was measured to ascertain whether this selection had caused correlated responses in behaviour: studies included feeding behaviour, open field behaviour, ultrasound calling rates of pups, and the response to the introduction of a novel physical object. Alterations in behavioural patterns which were expecteda prioriwere observed but there appeared to be no changes in behaviour associated with any one selection criterion. Estimates of the genetic correlations between selected and behavioural traits were, with one exception, generally less than 0·1 in magnitude and not significantly different from zero (the exception was food intake in lines selected on body weight). Assuming that mice are accurate models for commercial species, then these results have important implications for animal welfare: they demonstrate that large scale behavioural changes do not arise as an inevitable consequence of intense long-term selection on traits of economic importance in commercial species
Dosage compensation and sex-chromatin in non-mammals
Authors: Cock A. G. 
Published: September 2009

1. Inactivation of one X chromosome in somatic cells of female mammals is a form of dosage compensation of sex-linked genes, but the mechanism is entirely different from that operating inDrosophila. The latter is designated as dosage compensationsensu strictu.2. There is no dosage compensation of barred,sex-linked dilutionorslow-featheringin domestic fowls, ofalmondorfadedin pigeons, or ofcinnamonin canaries. Among Lepidoptera the same is true ofsex-linked melanisminLymantria monachaand of a locus controlling haemolymph colour inChoritoneuraspp. There is no positive evidence that dosage compensation occurs outside Drosophila and mammals.3. Sex-chromatin in female birds (heterogametic) has been reported by several authors; the genetical evidence is against the possibility that this represents (as in mammals) an inactivated X chromosome. Sex-chromatin in the heterogametic sex also occurs in some (not all) Lepidoptera and Heteroptera; in Heteroptera it usually represents a heteropyknotic Y chromosome.4. Some complications in Muller's theory of dosage compensationsensu strictuare discussed. Not all ‘compensatory modifiers’ are necessarily sex-linked.5. The problem of dosage compensation in species with impaternate males is discussed;fusedinHabrobraconis not compensated.
Grammatical analysis of DNA sequences provides a rationale for the regulatory control of an entire chromosome
Authors: Ohno Susumu 
Published: September 2009

SummaryRegardless of their origins, functions, and base compositions, all DNAs are scriptures written following the same grammatical rule. At the level of syllables, two, CG and TA are seldom used, while three, TG, CT and CA are utilized with abundance. Accordingly, at the level of three-letter words, two complementary base trimers, CTG and CAG, invariably enjoy frequent usage. Inasmuch as two of the three frequently used syllables, TG and CA are complementary to each other, while two seldom used syllables, CG and TA, are both palindromes, two complementary strands of DNA are inherently symmetrical with each other. Consequently, palindromic sequences as favourite targets of DNA-binding proteins occur at unsuspectedly high frequencies, if they contain TG and CA or CTG and CAG. Nevertheless, there are grammatical rules operating among these high frequency palindromes as well; e.g. the palindromic tetramer TGCA occurs nearly two times more often than its reciprocal; CATG. Thus, DNA-binding proteins are provided with a wealth of abundant targets whose densities are influenced by a regional difference in GC/AT ratios to variable degrees. One palindromic heptamer CAGNCTG is an ideal target of one DNA-binding protein engaged in chromosome packaging and in generation of banding patterns. This heptamer occurs once every 1000 bases in moderately GC-rich sequences, while its incidence is reduced to once every 3000 bases in extremely AT-rich sequences. The above must be the very reason that a solitary human X-chromosome DNA coated with mouse DNA-binding proteins in mouse-man somatic hybrids still maintains the original banding pattern and that the inactive X remains inactive, while the active X remains active.
Non-Profit Privatization of the Management of Nigerian Public Schools: A Legal and Policy Analysis
Authors: Adeniran Akingbolahan 
Published: September 2009

AbstractThe objective of this article is to analyse critically a government proposal to privatize the management of federally-run secondary schools in Nigeria. Although they have performed relatively well over the years, recent problems have led to a decline in academic standards in these schools. The article examines the potential merits and demerits of the proposed public-private partnership with a view to assessing whether the partnership can add value to the current public model. Although the analysis falls short of endorsing the proposed reform, the article recommends its phased implementation subject to the application of specific legal and practical considerations. It argues that there are enforceable limits to changes in secondary education policy and that the government has an obligation progressively to implement free and compulsory secondary education. It also highlights a number of practical matters meant to ensure that the best interests of any affected children will be taken into account.
Nigeria's Land Use Act: An Anti-Thesis to Environmental Justice
Authors: Ako Rhuks T 
Published: September 2009

AbstractNigeria's Land Use Act, promulgated in 1978, is perhaps the most controversial legislation in the country. The Act, originally promulgated as a decree and annexed to the country's constitution, was ostensibly made to nationalize landholding in the country. However, the peculiar impact of the Act on the inhabitants of the Niger Delta region that hosts upstream activities of the oil industry has led to assertions that the Act was made specifically to deprive those inhabitants of the right to participate actively in the oil industry. This article examines the impact of the Act on the right of inhabitants to access justice. It argues that the Act obstructs their rights to environmental justice and is a fundamental cause of the violent conflicts that pervade the region.
Susceptibility to praziquantel of male and female cercariae of praziquantel-resistant and susceptible isolates of Schistosoma mansoni
Authors: Liang Y.-S. , Wang W. , Dai J.-R. , Li H.-J. , Tao Y.-H. , Zhang J.-F. , Li W. , Zhu Y.-C. , Coles G.C. , Doenhoff M.J. 
Published: September 2009

AbstractPraziquantel (PZQ) is now widely used for the treatment of human schistosomiasis. However, in recent years, there has been a growing concern about the resistance of Schistosoma to PZQ. The mechanisms of PZQ action against Schistosoma and resistance of Schistosoma to PZQ are poorly understood. Here, we report differential susceptibilities to PZQ between male and female cercariae in the PZQ-susceptible and PZQ-resistant isolates of Schistosoma mansoni, using tail loss as a measurement of PZQ action. The miracidia were collected by hatching eggs collected from faeces of infected mice. Single-sex cercaria lines were made by infecting a single Biomphalaria glabrata snail with a single miracidium. The sex of each single-sex cercaria line was identified by a direct W1-specific polymerase chain reaction (PCR) technique. Single-sex cercariae of two isolates were exposed to four different concentrations of PZQ, respectively. The tail shedding of cercariae was observed under a dissecting microscope for five time points up to 100 min after adding PZQ. The results showed that male cercariae have higher tail-shedding rates than that of female cercariae when PZQ-susceptible isolates of S. mansoni are exposed to the same concentration of PZQ. But this phenomenon was not observed in the PZQ-resistant isolates. This sexual differential resistance phenomenon of S. mansoni suggests that resistance to PZQ is induced by decreasing the PZQ susceptibility of male worms. The experiment described here may also be useful for developing tests to detect PZQ resistance in the field.
Sex ratio and morphological polymorphism in an isolated, endemicTeladorsagia circumcinctapopulation
Authors: Craig B.H. , Pilkington J.G. , Pemberton J.M. 
Published: September 2009

AbstractTeladorsagia circumcinctais a polygamous nematode that exhibits morphological polymorphism. Sex ratio is typically female biased and the male nematodes occur in association with the genetically similar, minor morphotypesTeladorsagia davtianiandTeladorsagia trifurcata. In experimental infections, sex ratio (proportion male) and the proportion of minor male morphs observed have been shown to be influenced by both host and nematode-related factors. As similar investigations from natural systems are rare, this study examined whether sex ratio and minor male morph frequency were associated with host age and sex and nematode infra-population size in the isolated Soay sheep population on St Kilda. Count data forTeladorsagiawere analysed for sheep of all age classes and both sexes from the winters of three consecutive population crashes (1999, 2002 and 2005). Generally, the intensity ofTeladorsagianematodes increased with host age until the age of 2 years before decreasing. In 2005, abundance of nematodes was generally higher than in the previous crashes, nematode sex ratio was negatively associated with host age and tended to be negatively associated with nematode intensity. Within the male nematode subpopulation,T. circumcinctaalways predominated, followed byT. davtianiand thenT. trifurcata, with little variation in the relative proportions between hosts. The presence of each minor morph was primarily associated with the intensity of maleT. circumcinctaand, in those hosts where all three male morphs were detected, intensity of each minor morph was most associated with intensity ofTeladorsagiafemales. Therefore, in a year when the nematode was generally more abundant, sex ratio appeared to be influenced by both host and nematode-related factors, whereas in all years examined, the frequency of morphological polymorphism was primarily density dependent.
Diversity of metazoan parasites of the African catfish Clarias gariepinus (Burchell, 1822) as indicators of pollution in a subtropical African river system
Authors: Madanire-Moyo G. , Barson M. 
Published: September 2009

AbstractThe relationship between parasite species diversity and organic pollution in the upper Manyame catchment, Zimbabwe, was investigated between October 2006 and January 2007. The parasite assemblage comprised 13 species in total. Species richness in the unpolluted sites was high; in the moderately polluted sites, it was low, while in the polluted sites, only one parasite species was encountered. Component community diversity, as measured by the Shannon index (H′), decreased with increase in organic pollution. The distribution and occurrence of ectoparasites (Dolops ranarum, Lamproglena clariae, Chonopeltis sp. and Macrogyrodactylus sp.) and one endoparasite (Lytocestus sp.) were limited to the unpolluted sites, demonstrating their sensitivity to organic pollution. The prevalence of the nematodes Paracamallanus cyathopharynx, Procamallanus laevionchus and Contracaecum spp. larvae decreased along the pollution gradient, showing their high sensitivity to organic pollution. The platyhelminths Diplostomum sp. and Polyonchobothrium clarias were the most tolerant and occurred at both polluted and unpolluted sites. Proteocephalus sp. and Caryophyllaeus sp. were limited to the polluted sites, probably as a result of high abundance of oligochaetes and copepods, their intermediate hosts that thrive in sewage-enriched sediments, at the downstream sites. The observed results assume that the decrease in parasite diversity can be related to increased organic pollution. Some parasites requiring complex life histories were absent along with pollution-related disappearance of their vector hosts. Further studies should address the identification of parasite life stages that are more sensitive to pollutants.
Cervical tuberculous lymphadenitis in the elderly: comparative diagnostic findings
Authors: Kato T , Kimura Y , Sawabe M , Masuda Y , Kitamura K 
Published: September 2009

AbstractBackground:Patients suspected of having cervical tuberculous lymphadenitis are diagnosed using investigations such as fine needle aspiration cytology and the polymerase chain reaction for Mycobacterium tuberculosis. However, these investigations are intended for primary tuberculosis infection. The majority of cervical tuberculous lymphadenitis cases in the elderly are thought to be caused by reactivation.Objective:The aims of this study were (1) to examine the efficacy of fine needle aspiration cytology, polymerase chain reaction and blood tests in the diagnosis of cervical tuberculous lymphadenitis caused by reactivation, and (2) to clarify any differences when compared with primarily infected cervical tuberculous lymphadenitis cases.Materials and methods:Thirty-three elderly patients with neck lumps underwent excisional biopsy from 2003 to 2008. The efficacy of fine needle aspiration cytology was examined by comparing the results of excisional biopsy with those of fine needle aspiration cytology performed at the initial medical examination for cases of suspected tuberculous disease. Furthermore, the leucocyte count and C-reactive protein concentration were compared for cases of cervical tuberculous lymphadenitis versus cases of malignant lymphoma.Results:Although nine cases were diagnosed with cervical tuberculous lymphadenitis using excisional biopsy, only one of these had been suspected based on fine needle aspiration cytology results. Three cases with tuberculous lymphadenitis were suspected of having malignant lymphoma on initial examination. There was no significant difference in the leucocyte count and C-reactive protein concentration, comparing cases of tuberculous lymphadenitis versus malignant lymphoma.Conclusion:Unlike the primary infection often seen in endemic areas, the diagnosis of early stage tuberculous lymphadenitis of the swelling type caused by reactivation in elderly people is difficult to confirm unless excisional biopsy is performed. In elderly patients with neck lumps, cervical tuberculous lymphadenitis should be included in the differential diagnosis.
Post-tonsillectomy pseudoaneurysm: an underestimated entity?
Authors: Windfuhr J P , Sesterhenn A M , Schloendorff G , Kremer B 
Published: September 2009

AbstractObjective:To identify patients undergoing arteriography to verify vascular complications of tonsillectomy, with an emphasis on pseudoaneurysm.Patients and methods:We undertook a retrospective analysis of the case records of 8837 patients who had undergone tonsillectomy between 1988 and 2004 at our institution, together with a review of expert reports written for professional boards and civil courts as well as personal experiences or communication. We also conducted a literature review using the PubMed database.Results:We identified seven cases with vascular abnormalities. In addition, we identified three cases of pseudoaneurysm formation, involving two children and one adult patient, with bleeding 21, 36 and 58 days after tonsillectomy. Successful management included embolisation (two patients) and revision surgery (one patient).Conclusion:Post-tonsillectomy pseudoaneurysm formation is extremely rare and unrestricted by age. Correct diagnosis depends largely on a high index of clinical suspicion. Delayed and repeated episodes of gushing haemorrhage with spontaneous cessation appear to be a significant clinical marker. Immediate arteriography, with simultaneous embolisation, is highly recommended. The lingual artery is the most commonly involved vessel.
Magnetic resonance imaging of branchial cleft abnormalities: illustrated cases and literature review
Authors: Black C J , O'Hara J T , Berry J , Robson A K 
Published: September 2009

AbstractObjective:We report two cases of branchial cleft abnormalities investigated using magnetic resonance imaging.Background:There appears to be no clear imaging technique that is universally recommended for imaging branchial cleft abnormalities. Options include fistulography, computed tomography, magnetic resonance imaging and ultrasonography.Method:Case reports and literature review.Case reports:Two cases, although not unusual in themselves, are described to illustrate the use of magnetic resonance imaging to define the anatomy and to assist surgical planning.Conclusion:Magnetic resonance imaging is able to accurately depict the extent and course of branchial cleft abnormalities, and in the current cases could have been relied upon to determine the necessary surgical procedure. Branchial cleft abnormalities are sufficiently rare for magnetic resonance imaging to be recommended as the first-line imaging modality.
The dangers of kite flying: pseudoaneurysm of the facial artery following blunt trauma
Authors: Hettige R , Snelling J , Bleach N 
Published: September 2009

AbstractObjective: Pseudoaneurysms of the facial artery are an extremely rare development after blunt trauma. This paper aims to demonstrate the challenges faced during the diagnosis and subsequent management of this unusual cause of neck swelling.Method: We report the presentation, examination, investigation, management and potential complications of a case of facial artery pseudoaneurysm secondary to blunt arterial trauma, sustained from the string of a flying kite. We also review some of the relevant literature on this subject.Conclusions: Although a traumatic pseudoaneurysm is a rare occurrence in the facial region, the inclusion of this lesion in the differential diagnosis of soft tissue lesions caused by blunt trauma is important if the serious consequences of haemorrhage or thromboembolic disease are to be avoided. Prompt access to radiological imaging, and multi-disciplinary team input, are essential for effective diagnosis and management.