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《Theriogenology》2013,79(9):1987-1996
Kisspeptides (KiSS) are a recently discovered family of neuropeptides with a central role in regulating the onset of reproductive function in all animals studied to date. We have established biological and physiological evidence for KiSS signaling in the mare. The objective of the current study was to evaluate the physiological and behavioral responses of mares repeatedly given the equine-specific kisspeptpin decapeptide (eKp-10, YRWNSFGLRY-NH2) in an effort to shorten the interovulatory period. Administration of eKp-10 (0.5 mg iv every 4 h) to mares beginning on Day 16 postovulation (Group 2) or in estrus (Group 3) did not shorten the mean ± SEM interovulatory interval compared with untreated (Group 1) controls (21.9 ± 1.2, 22 ± 1.2, and 21.5 ± 1.5 days in Groups 1 to 3, respectively; N = 6 per group), nor was there a significant difference in follicle diameter before ovulation among groups, nor number of days treated with eKp-10 for Groups 2 and 3. Mean daily concentrations of FSH, the preovulatory LH surge (timing, mean, and peak concentrations), and mean progesterone concentrations from the newly formed CL were not significantly different among groups. The initiation of treatment was negatively correlated with sexual receptivity (scored 0 to 5: no interest to strong interest) and serum estradiol concentrations, indicating that eKp-10 can significantly disrupt normal sexual receptivity in the estrous mare. This effect on sexual receptivity was short-lived (< 72 h) and the overall change in sexual receptivity score was not significantly different between Groups 2 and 3 (−1.2 ± 0.5 and −1.4 ± 0.4, respectively). However, the day of the cycle that treatment was initiated significant affected the decline in sexual receptivity score, such that the later in the cycle that treatment was initiated, the greater the estimated decrease in sexual receptivity. In conclusion, the linear hypothalamic-pituitary mechanism for KiSS described in other species was not appropriate for the horse and administration of eKp-10 in the seasonally estrous mare may have been outside of the hormone's normal physiological context. 相似文献
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Insertional mutagenesis resulting in a leukaemia-like lymphoproliferative disease, as observed in the X-SCID (severe combined immunodeficiency) clinical trial using a gamma-retroviral vector that transferred a functional copy of the defective gene into hematopoietic precursor cells of affected children, sparked a debate about a ban on conventional gamma-retroviral vectors. This commentary summarizes the relevant data on this topic and concludes that there is no preclinical or clinical evidence as yet that SIN vectors, which self-inactivate the retroviral long terminal repeats (LTRs), will indeed show an improved safety profile. Conventional murine leukaemia virus (MLV) vectors can thus be used further in clinical gene therapy trials but require a thorough case-by-case risk-benefit analysis. 相似文献
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Is it better to combine predictions? 总被引:2,自引:0,他引:2
King RD Ouali M Strong AT Aly A Elmaghraby A Kantardzic M Page D 《Protein engineering》2000,13(1):15-19
We have compared the accuracy of the individual protein secondary structure prediction methods: PHD, DSC, NNSSP and Predator against the accuracy obtained by combing the predictions of the methods. A range of ways of combing predictions were tested: voting, biased voting, linear discrimination, neural networks and decision trees. The combined methods that involve 'learning' (the non-voting methods) were trained using a set of 496 non-homologous domains; this dataset was biased as some of the secondary structure prediction methods had used them for training. We used two independent test sets to compare predictions: the first consisted of 17 non-homologous domains from CASP3 (Third Community Wide Experiment on the Critical Assessment of Techniques for Protein Structure Prediction); the second set consisted of 405 domains that were selected in the same way as the training set, and were non-homologous to each other and the training set. On both test datasets the most accurate individual method was NNSSP, then PHD, DSC and the least accurate was Predator; however, it was not possible to conclusively show a significant difference between the individual methods. Comparing the accuracy of the single methods with that obtained by combing predictions it was found that it was better to use a combination of predictions. On both test datasets it was possible to obtain a approximately 3% improvement in accuracy by combing predictions. In most cases the combined methods were statistically significantly better (at P = 0.05 on the CASP3 test set, and P = 0.01 on the EBI test set). On the CASP3 test dataset there was no significant difference in accuracy between any of the combined method of prediction: on the EBI test dataset, linear discrimination and neural networks significantly outperformed voting techniques. We conclude that it is better to combine predictions. 相似文献
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Hayfa Khuder Alexia Stokes Frédéric Danjon Kyriaki Gouskou Frédéric Lagane 《Plant and Soil》2007,295(1-2):293-295
The optimal root system architecture for increased tree anchorage has not yet been determined and in particular, the role of the tap root remains elusive. In Maritime pine (Pinus pinaster Ait.), tap roots may play an important role in anchoring young trees, but in adult trees, their growth is often impeded by the presence of a hard pan layer in the soil and the tap root becomes a minor component of tree anchorage. To understand better the role of the tap root in young trees, we grew cuttings (no tap root present) and seedlings where the tap root had (?) or had not (+) been pruned, in the field for 7 years. The force (F) necessary to deflect the stem sideways was then measured and divided by stem cross-sectional area (CSA), giving a parameter analogous to stress during bending. Root systems were extracted and root architecture and wood mechanical properties (density and longitudinal modulus of elasticity, E L ) determined. In seedlings (?) tap roots, new roots had regenerated where the tap root had been pruned, whereas in cuttings, one or two lateral roots had grown downwards and acted as tap roots. Cuttings had significantly less lateral roots than the other treatments, but those near the soil surface were 14% and 23% thicker than plants (+) and (?) tap roots, respectively. Cuttings were smaller than seedlings, but were not relatively less resistant to stem deflection, probably because the thicker lateral roots compensated for their lower number. Apart from stem volume which was greater in trees (+) tap roots, no significant differences with regard to size or any root system variable were found in plants (?) or (+) tap roots. In all treatments, lateral roots were structurally reinforced through extra growth along the direction of the prevailing wind, which also improved tap root anchorage. Predictors of log F/CSA differed depending on treatment: in trees (?) tap roots, a combination of the predictors stem taper and %volume allocated to deep roots was highly regressed with log F/CSA (R 2 = 0.83), unlike plants (+) tap roots where the combined predictors of lateral root number and root depth were best regressed with log F/CSA (R 2 = 0.80). In cuttings, no clear relationships between log F/CSA and any parameter could be found. Wood density and E L did not differ between roots, but did diminish with increasing distance from the stem in lateral roots. E L was significantly lower in lateral roots from cuttings. Results showed that nursery techniques influence plant development but that the architectural pattern of Maritime pine root systems is stable, developing a sinker root system even when grown from cuttings. Anchorage is affected but the consequences for the long-term are still not known. Numerical modelling may be the only viable method to investigate the function that each root plays in adult tree anchorage. 相似文献
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Targeted modification of the genome has long been an aim of many geneticists and biotechnologists. Gene targeting is a main
molecular tool to examine biological effects of genes in a controlled environment. Effective gene targeting depends on the
frequency of homologous recombination that is indispensable for the insertion of foreign DNA into a specific sequence of the
genome. The main problem associated with the development of an optimal procedure for gene targeting in a particular organism
is the variability of homologous recombination (HR) in different species. Chlamydomonas reinhardtii is an attractive model system for the study of many cellular processes and is also an interesting object for the biotechnology
industry. In spite of many advantages of this model system, C. reinhardtii does not readily express heterologous genes and does not allow targeted integration of foreign DNA into its genome easily.
This paper compares data obtained from several different experiments designed for improving gene targeting in different organisms
and reviews the suitability of particular techniques in C. reinhardtii cells.
Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia. 相似文献
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Hematophagous arthropods that transmit the etiological agents of arthropod-borne diseases have become the focus of anti-vector vaccines, targeted mainly at components of their saliva and midgut. These efforts have been directed mostly towards developing species-specific vaccines. An alternative is to target cross-reactive epitopes that have been preserved during evolution of the arthropods. The N- and O-linked glycans that are attached to arthropod glycoproteins are one of the potential targets of this pan-arthropod vaccine approach. Here, we discuss how genetically modified Drosophila melanogaster cells can be used to synthesize and to deliver these arthropod glycans to vertebrate hosts. 相似文献
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Rachels S 《Bioethics》1998,12(2):93-110
Would it be good, other things being equal, for additional people to exist whose lives would be worth living? I examine and reject several arguments for the answer that it would not be good; then I offer opposing arguments that I believe are more successful. Thus, I agree with utilitarians who say that it is better for there to be more happy people. Next I argue for the stronger claim that the happiness of potential people is as important as that of adults. Potential quality of life, then, matters in a host of bioethical issues: abortion, commercial surrogacy, the treatment of defective newborns, and so on. What is the practical upshot of all this? I reject the idea that we must do whatever is necessary to prolong life worth living. But I also reject the view that the side-effects of overpopulation always outweigh the value of realizing potential happiness. So I advocate a middle position, which I do not identify precisely. Even from this middle position, however, potential happiness is more important than is commonly assumed in bioethics. 相似文献
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Fernando Kemta Lekpa Cécile Poulain Daniel Wendling Martin Soubrier Michel De Bandt Jean Marie Berthelot Philippe Gaudin Eric Toussirot Philippe Goupille Thao Pham Jérémie Sellam Rémy Bruckert Muriel Paul Valérie Farrenq Pascal Claudepierre 《Arthritis research & therapy》2012,14(2):R53-9