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81.
On the chromosomes of the rooster the constitutive heterochromatin (C-bands) is to be found for the most part at the centromeres. The position of the centric heterochromatin in spermatids and sperm is not randomly distributed. In early, round spermatids one heterochromatic block lies at this exact position on the membrane that develops into the tip of the sperm nucleus (acrosomal chromocenter). During the elongation of the spermatid nucleus another heterochromatic block comes to lie on the basal nuclear membrane. The other centromeres arrange themselves tandem-wise between the acrosomal and the basal chromocenters. Comparisons have been made between this specific arrangement and the location of chromosomes in the sperm of amphibians and mammalians. 相似文献
82.
Stefan Dressler 《Curtis's Botanical Magazine》1997,14(3):130-136
83.
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85.
Pax2, a new murine paired-box-containing gene and its expression in the developing excretory system 总被引:27,自引:0,他引:27
G R Dressler U Deutsch K Chowdhury H O Nornes P Gruss 《Development (Cambridge, England)》1990,109(4):787-795
The murine genome contains multiple genes with protein domains homologous to the Drosophila paired box, present in certain segmentation genes. At least one of these murine paired box (Pax) genes is associated with a developmental mutation. This report, in conjunction with the accompanying paper, describes a second member of this gene family, Pax2, that is also expressed during embryogenesis. Two overlapping cDNA clones were isolated and sequenced. At least two forms of the Pax2 protein can be deduced from the cDNA sequence. In addition to the highly conserved paired domain, an octapeptide sequence is located downstream. Expression of Pax2 is primarily restricted to the developing embryo in the excretory and central nervous systems. The transient nature of Pax2 expression during kidney organogenesis correlates with polarization and induction of epithelial structures and may indicate an important morphogenetic role for this gene. 相似文献
86.
Fat depot‐specific expression of HOXC9 and HOXC10 may contribute to adverse fat distribution and related metabolic traits
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87.
Anne Riemer Grzegorz Dobrynin Alina Dressler Sebastian Bremer Aashish Soni George Iliakis 《Cell cycle (Georgetown, Tex.)》2014,13(6):919-927
The p97-Ufd1-Npl4 ATPase complex is associated with the response to DNA damage and replication stress, but how its inactivation leads to manifestation of chromosome instability is unclear. Here, we show that p97-Ufd1-Npl4 has an additional direct role in the G2/M checkpoint. Upon DNA damage, p97-Ufd1-Npl4 binds CDC25A downstream of ubiquitination by the SCF-βTrCP ligase and facilitates its proteasomal degradation. Depletion of Ufd1-Npl4 leads to G2/M checkpoint failure due to persistent CDC25 activity and propagation of DNA damage into mitosis with deleterious effects on chromosome segregation. Thus, p97-Ufd1-Npl4 is an integral part of G2/M checkpoint signaling and thereby suppresses chromosome instability. 相似文献
88.
Swidden Transformations and Rural Livelihoods in Southeast Asia 总被引:5,自引:4,他引:1
R. A. Cramb Carol J. Pierce Colfer Wolfram Dressler Pinkaew Laungaramsri Quang Trang Le Elok Mulyoutami Nancy L. Peluso Reed L. Wadley 《Human ecology: an interdisciplinary journal》2009,37(3):323-346
This paper explores the major interactions between the transformation of swidden farming and the pursuit of rural livelihoods
in the uplands of Southeast Asia. The paper draws on selected literature, workshop reflections, and six case studies to describe
the causal processes and livelihood consequences of swidden change. Household-level livelihood responses have included both
the intensification and ‘dis-intensification’ of swidden land-use, the insertion of cash crops, the redeployment of household
labour, and the taking on of broader (often non-rural) livelihood aspirations and strategies. At the community level there
have been emerging institutional arrangements for management of land and forests, and varying degrees of participation in
or resistance to government schemes and programs. Swidden change has led to the loss and also the reassertion, realignment,
and redefinition of cultures and identities, with important implications for access to resources. The impacts of these changes
have been varied. Cash crops have often improved livelihoods but complete specialisation for the market increases vulnerability.
Thus swidden can still provide an important safety net in the face of market fluctuations. Improved access to markets and
social provision of education and health care have mostly improved the welfare of previously isolated groups. However, growing
differences within and between communities in the course of swidden transformations can leave some groups marginalized and
worse off. These processes of differentiation can be accentuated by heavy-handed state interventions based on swidden stereotypes.
Nevertheless, communities have not passively accepted these pressures and have mobilized to protect their livelihood assets
and strategies. Thus swidden farmers are not resisting appropriate and supportive forms of development. They are adopting
new practices and engaging with markets, but in many situations swidden is still important to their livelihood strategies,
providing resilience in the face of turbulent change. Active involvement of local people is essential in planning, implementing,
monitoring and evaluating development and conservation programs in swidden lands. Positive market incentives and supportive
government policies are better than standardised, top-down directives.
相似文献
R. A. CrambEmail: |
89.
By 2030, there will be 70 million people in the United States over the age of 65, and by 2050, 22% of the US population will be considered elderly. It is generally believed that injuries in the elderly heal slower and less completely than in adolescents or young adults. To evaluate aging effects on tissue repair a surgical injury was created in the middle third of one patellar tendon in 1- and 4-5-year-old New Zealand White rabbits. The biomechanical properties of the isolated repair tissues and contralateral normal tendon tissues were compared at 6, 12 and 26 weeks post-injury. We hypothesized that repair tissues would exhibit age-related reductions in biomechanical properties at all time intervals of healing, both based on raw data and when normalized to values from contralateral tendons. Repairs from both age groups were similar, with no significant increase in maximum stress, strain at maximum stress, or modulus between 6 and 12 weeks. At 26 weeks, the repairs in the 4-year-old rabbits had higher maximum stress values than repairs in the 1-year-old rabbits (p=0.03). There were no significant differences in the strain at maximum stress or modulus. When repair tissue properties were normalized to values in the contralateral normal tendon, the maximum stress of the patellar tendon repair tissue from the 4 year old was significantly greater than the corresponding value from the 1 year old at the 26 week time point (p=0.04). In conclusion, these findings do not support the presence of age-related declines in the biomechanics of healing tendon. 相似文献
90.
Ornithocephalus aristatus, a new species from Panama, is described and illustrated. Among the species of the genusOrnithocephalus, it can be distinguished by the nonresupinate flowers, the sepals each provided with a flexuous awn half as long as the sepal
itself, the porrect petals with revolute margins, the hastate lip with triangular-ovate, crose lateral lobes, the linear,
acute midlobe, conduplicate and subreflexed at apex, and the dise with a bilobed, obreniform callus provided with a conical
tuft of stiff hairs. A key to the species ofOrnithocephalus from Panama is provided. 相似文献