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111.
Responses of rat kidney and toad bladder to the pentapeptide ring structures of neurohypophysial hormones 总被引:1,自引:0,他引:1
112.
113.
The synthesis of the enantiomers of 2,2-difluoro-2-deoxy-myo-inositol 1,4,5-trisphosphate is reported. L-2,2-difluoro-2-deoxy-myo-inositol 1,4,5-trisphosphate is a potent inhibitor of 3-kinase and 5-phosphatase. 相似文献
114.
Epithelial-mesenchymal interactions play important roles in morphogenesis, histogenesis, and keratinization of the vertebrate integument. In the anterior metatarsal region of the chicken, morphogenesis results in the formation of distinct overlapping scutate scales. Recent studies have shown that the dermis of scutate scales is involved in the expression of the beta keratin gene products, which characterize terminal differentiation of the epidermis on the outer scale surface (Sawyer et al.: Dev. Biol. 101:8-18, '84; Shames and Sawyer: Dev. Biol. 116:15-22, '86; Shames and Sawyer: In A.A. Moscona and A. Monroy (eds), R.H. Sawyer (Vol. ed): Current Topics in Developmental Biology. Vol. 22: The Molecular and Developmental Biology of Keratins. New York: Academic Press, pp. 235-253, '87). Since alpha and beta keratins are both found in the scutate scale and are members of two different multigene families, it is important to know the precise location of these distinct keratins within the epidermis. In the present study, we have used protein A-gold immunoelectron microscopy with antisera made against avian alpha and beta keratins to specifically localize these keratins during development of the scutate scale to better understand the relationship between dermal cues and terminal differentiation. We find that the bundles of 3-nm filaments, characteristic of tissues known to produce beta keratins, react specifically with antiserum which recognizes beta keratin polypeptides and are found in the embryonic subperiderm that covers the entire scutate scale and in the stratum intermedium and stratum corneum making up the platelike beta stratum of the outer scale surface. Secondly, we find that 8-10-nm tonofilaments react specifically with antiserum that recognizes alpha keratin polypeptides and are located in the germinative basal cells and the lowermost cells of the stratum intermedium of the outer scale surface, as well as in the embryonic alpha stratum, which is lost from the outer surface of the scale at hatching. The alpha keratins are found throughout the epidermis of the inner surface of the scale and the hinge region. Thus, the present study further supports the hypothesis that the tissue interactions responsible for the formation of the beta stratum of scutate scales do not directly activate the synthesis of beta keratins in the germinative cells but influence these cells so that they or their progeny will activate specific beta keratin genes at the appropriate time and place. 相似文献
115.
Retinoic acid-induced transformation of reticulate scales to feather-like structures (Dhouailly and Hardy, '78) provides a useful model to study biochemical differentiation in avian skin. In this study, immunofluorescent analysis of reticulate scale-feathers (RSFs) indicates that they contain beta keratin in feather barbs and, thus, are true feathers, biochemically. Epidermal cells that would otherwise produce only alpha keratin in reticulate scales are induced to reorganize and differentiate into barb ridge cells that accumulate feather beta keratins. The mechanism for these dramatic morphological and biosynthetic responses to retinoic acid is unknown. 相似文献
116.
Richard Spinney Lee Smith Marcella Ucci Abigail Fisher Marina Konstantatou Alexia Sawyer Jane Wardle Alexi Marmot 《PloS one》2015,10(5)
Little is known of the patterns of physical activity, standing and sitting by
office workers. However, insight into these behaviours is of growing interest,
notably in regard to public health priorities to reduce non-communicable disease
risk factors associated with high levels of sitting time and low levels of
physical activity. With the advent and increasing availability of indoor
tracking systems it is now becoming possible to build detailed pictures of the
usage of indoor spaces. This paper reports initial results of indoor tracking
used in conjunction with the ActivPAL activity monitoring device. In this paper
we give an overview of the usage of the tracking system and its installation and
illustrate some of the resultant data. We also provide preliminary results that
investigate the relationship between location, light physical activity and
sitting in a small sample of office workers (n=33) from two separate office
environments in order to demonstrate the relevance and explanatory power of the
technique. 相似文献
117.
T K Sawyer 《Applied and environmental microbiology》1989,55(5):1074-1077
Tests for potentially pathogenic amoebae were carried out on soil samples from the following sites: (i) farmlands fertilized with municipal sewage wastes, (ii) a stream receiving sewage effluent from a sludge lagoon, (iii) a ravine receiving storm runoff from a cattle farm, (iv) farmlands not fertilized with sewage wastes, and (v) a vegetated shoreline of a waterfront estate not used for farming or livestock production. Study sites were located on the eastern shore of Maryland, bordered to the north by Delaware and to the south by Virginia. Twenty-four species of soil amoebae, including five potentially pathogenic Acanthamoeba species (members of the family Acanthamoebidae), were identified. All of the sites yielded two or more of the potential pathogens. 相似文献
118.
Llinos G. Harris Yamni Nigam James Sawyer Dietrich Mack David I. Pritchard 《Applied and environmental microbiology》2013,79(4):1393-1395
Staphylococcus aureus and Staphylococcus epidermidis biofilms cause chronic infections due to their ability to form biofilms. The excretions/secretions of Lucilia sericata larvae (maggots) have effective activity for debridement and disruption of bacterial biofilms. In this paper, we demonstrate how chymotrypsin derived from maggot excretions/secretions disrupts protein-dependent bacterial biofilm formation mechanisms. 相似文献
119.
- Many organisms contribute to the decomposition of carrion. For arthropods, many studies focus on the necrophagous community, those directly consuming carrion.
- Necrophagous arthropods use carrion as a shelter or food source. Therefore, carrion generally increases the abundance and biodiversity of necrophagous species. However, it is unclear if carrion has similar effects on detrital communities.
- This study examines changes in community structure and composition of necrophilous and detrital communities over the course of decomposition.
- Five pig head carrion were placed at least 7 m apart under cages in temperate mixed forest. Leaf litter was sampled 0 m, 1.5 m, and 3 m from each carrion weekly during summer, and monthly during autumn, until the first frost. Arthropods were extracted from leaf litter by using Berlese funnels.
- At the carrion site, necrophagous insects increased in abundance, species richness, and Shannon diversity during decomposition, and all decreased after dry decay.
- Detritus arthropods displayed a sharp increase in abundance during advanced decay, decreasing during dry decay, and a general increase over time for species richness and diversity.
- In conclusion, carrion can influence the surrounding, non-necrophagous arthropod community, highlighting the need to investigate carrion effects beyond typical necrophagous species to have a more holistic understanding of carrion ecology.
120.
Wilbur A. Sawyer 《The Western journal of medicine》1915,13(12):494-495