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1.
This paper outlines the relevance of the idea of rhythm to cultural anthropology, with specific suggestions for a medical anthropology of rhythm. By reconsidering the fluid nature of the concept of rhythm in ordinary language, the paper defines rhythm functionally in terms of a temporal order that anticipates, suspends and fulfills on the level of the visceral, physical, ecological, institutional as well as the moral. Although the paper identifies most explicitly the link between the bodily and social rhythm, it tries to suggest a cosmic background in the interaction of the social and bodily rhythms. The paper is divided into three parts: 1) the general problem of defining rhythm, 2) the concept of rhythm from its origin, and 3) the concept of rhythm in cultural theory since Durkheim. Further readings in particular reference to medical anthropology are often indicated in the notes.I want to thank Arthur Kleinman and Joan Kleinman for their unfailing support and comradely criticism throughout my reading and writting for this paper.  相似文献   

2.
The previous issue of Culture, Medicine and Psychiatry (Vol. 5, N. 4) included my article When Rational Men Fall Sick: An Inquiry into Some Assumptions Made by Medical Anthropologists together with a series of comments. This paper consists of my replies to some of the commentators and a case study illustrating my points.My collaborators in this research were two physicians, Dr. Robert Like, of the Department of Family Practice of Case Western Reserve University and Dr. Rivka Plotkin of the Ben-Gurion University of the Negev (Israel). Also, I want to thank Avraham Blidstein for his invaluable assistance.  相似文献   

3.
The initial biochemical characterization of the soybean sucrose-binding protein, GmSBP, within our lab and others produced several incongruous characteristics that required a re-characterization of GmSBP via sequence homology, cell biology, immunolocalization, and semi-quantitative analysis. The GmSBP proteins share amino acid sequence homology as well as putative structural homology with globulin-like seed storage proteins. A comparison to the major soybean seed storage proteins, glycinin and -conglycinin established several storage protein-like characteristics for GmSBP. All three proteins were present in a prevacuolar compartment and protein storage vacuole. All three proteins increased in expression during seed development and are remobilized during germination. Quantitatively, the relative concentrations of GmSBP, -conglycinin (/ subunits), and glycinin (acidic subunits) indicated that GmSBP contributes 19-fold less to the stored nitrogen. The quantitative differences between GmSBP and glycinin may be attributed to the unconserved order and spacing of cis-acting regulatory elements present within the promoter regions. Ultimately, GmSBP is transported to the mature protein storage vacuole. The biological function of GmSBP within the protein storage vacuole remains uncertain, but its localization is a remnant of its evolutionary link to a globulin-like or vicilin-like ancestor that gave rise to the 7S family of storage proteins.  相似文献   

4.
Seventeen species ofHemileia were studied with emphasis on these characters: extent of colonization, specialization of parasitic mycelium, haustorial development, pathologic histology, soral morphology and sporulation capacity. An attempt was made to trace the varying degree of development and parasitism in this rust genus comprising of just over 40 reported species. It was noted that theGopalkrishnan's Subepidermal type more advanced than his Superstomal — B type.Fourth part of my thesis submitted to the University of Poona, India, accepted in 1968 for Ph.D. Not published.  相似文献   

5.
Conclusion Shortly after the October Revolution, Semenov-Tian-Shanskii prophetically remarked that voices in defense of nature in Russia under the new regime might be nothing more than miserable voices crying in the wilderness.52 Alas, this turned out to be all too true: by the end of the 1930s the voices of the aestheticethical approach had become silent in the wilderness of socialist construction.Nevertheless, I would not like to conclude my talk on this mournful note. Instead I would like to emphasize that, although the history of Russian environmental ethics turned out to be tragically brief, its basic ideas seem to me to be still relevant and important today. What I consider perhaps most important is the idea that is best expressed in Semenov-Tian-Shanskii's words: freedom is necessary for nature as it is necessary for humans.53 This outlook calls us to surrender our pretensions to ontological superiority over the rest of nature. It calls us to recognize that nature is valuable in itself, and to live in harmonious cooperation with nature. *** DIRECT SUPPORT *** A8402064 00008  相似文献   

6.
Robert Netting had a central role in establishing agricultural anthropology. Many people rightly remember him as an astute ethnographer of farming communities, focused on analyzing the empirical details of changing patterns of household composition, land holding size and labor use. Yet, during his career he was increasingly concerned about the sustainability of smallholder vs. conventional industrial agriculture models on a global scale. Thus, Netting also had an important role in laying the foundation for the development of an agricultural anthropology for the twenty-first century, an anthropology that shows how smallholders balancing on an Alp can help us to understand how we might balance on this planet. This paper analyzes Netting's contribution to the future of agricultural anthropology in three key areas: the environment, population, and agriculture relationship; farmer knowledge and epistemology; and models for global sustainability.  相似文献   

7.
The effects of a series of bisbenzyldiamine analogs have been tested on P388D1 cell line in vitro. Their effects on cell growth, polyamine oxidase (PAO) activity and intracellular polyamine content were determined. The cytotoxicity tests were performed in culture medium supplemented with 100 mol/L aminoguanidine (I), 100 mol/L aminoguanidine and 100 mol/L N,N-bis(2,3-butadienyl)-1,4-butanediamine (MDL 72,527) (II), and finally 100 mol/L aminoguanidine and 200 mol/L D,L-difluoromethylornithine (DFMO) (III). The IC50 values under conditions I and III were similar, suggesting that inhibition of ornithine decarboxylase by DFMO did not affect the biological effect of our derivatives. Spermine and spermidine remained nontoxic in conditions I and III. However in the condition II, the toxicity of all tested compounds (excepted spermidine) was increased, suggesting that the inhibition of cellular PAO increased their toxicity.The enzymatic test of PAO showed that at high doses inhibition of this enzyme by putrescine analogs occurred, while the N-methylated propanediamine derivative increased the enzyme activity; however, these results do not correlate with cytotoxicity tests. When these derivatives were incubated for 48 h with the cells, all of them increased the cell content in putrescine (160%) and spermine (145%) and decreased the spermidine content (75%) without any modification of the total amount of polyamine.The correlation between the cytotoxic results and the intracellular polyamine determination shows that the increase in spermine content along with the inhibition of retroconverting PAO enzyme increases the toxic effect of tested compounds (including spermine), suggesting that spermine toxicity is more important in the absence of intracellular oxidation processes.  相似文献   

8.
Summary Gene localization studies revealed the presence of two structural -galactosidase (GAL) loci on the human chromosomes 3 and 22 (de Wit et al., 1979). To determine the function of these genes, proliferating hybrid cell lines were isolated following fusion of fibroblasts from two different patients with a GAL deficiency and Chinese hamster cells. The hybrids were analyzed electrophoretically and immunologically.Fibroblasts from a patient with an adult type of GAL deficiency associated with a neuraminidase deficiency were used for the first fusion. No evidence for a structural GAL mutation was found in these hybrids. The absence of a structural GAL mutation is consistent with a primary defect in neuraminidase in this adult patient.Fibroblasts from a patient with the infantile type 1 GM1-gangliosidosis were used for the second fusion. It is concluded that the human determinants present in the isolated hybrid lines occur in heteropolymeric man-Chinese hamster molecules. The heteropolymeric isoenzyme in (+3–22) hybrids is very labile and is sensitive to neuraminidase treatment. Therefore it is concluded that the infantile type 1 patient is mutated in the structural GAL gene on chromosome 3. Because this patient has a primary defect in GM1-GAL, the GAL gene on chromosome 3 is apparently a G M1-GAL gene. Interaction of the two GAL loci results in an additional band of GAL activity on electrophoresis. This suggests that the gene on chromosome 22 is also a structural G M1-GAL gene.  相似文献   

9.
The action of thyroid hormones on the expression of the mitochondrial ATP synthase -subunit gene (ATPsyn) is controversial. We detected a binding site for the thyroid hormone receptor between-366 and-380 in the human ATPsyn gene by DNase I footprint analysis and band-shift assays. However, expression vectors in which the chloramphenicol acetyl transferase (CAT) reporter gene is driven by the 5 upstream region of ATPsyn gene were unresponsive to T3 when transiently transfected to HepG2 or GH4C1 cells. CAT constructs driven by the rat phosphoenolpyruvate carboxykinase (PEPCK) or the growth hormone (GH) promoters were stimulated several fold by T3 in parallel experiments. It is proposed that the biological effects of thyroid hormones on the ATPsyn expression occur through indirect mechanisms.  相似文献   

10.
Expression of a chimeric stilbene synthase gene in transgenic wheat lines   总被引:11,自引:0,他引:11  
A chimeric stilbene synthase (sts)gene was transferred into wheat. Stilbene synthases play a role in the defence against fungal diseases in some plant species (e.g. groundnut or grapevine) by producing stilbenetype phytoalexins like resveratrol. Resveratrol is also claimed to have positive effects to human health. Embryogenic scutellar calli derived from immature embryos of the two commercial German spring wheat cultivars Combi and Hanno were used as target tissue for cotransformation by microprojectile delivery. The selectable marker/reporter gene constructs contained the bargene either driven by the ubiquitinpromoter from maize (pAHC 25, also containing the uidAgene driven by the ubiquitinpromoter), or by the actinpromoter (pDM 302) from rice. The cotransferred plasmid pStil 2 consisted of a grapevine stscoding region driven by the ubiquitin promoter. Eight transgenic Combi and one Hanno TOplant were obtained and, except one Combi TOplant, found to be cotransformants due to the integration of both the stsgene and the selectable marker or reporter genes. Expression of the stsgene was proven by RTPCR, and, for the first time, by detection of the stilbene synthase product resveratrol by HPLC and mass spectrometry. The stsgene was expressed in four of the seven transgenic Combi T_oplants. Two of the respective T1progenies segregated in a Mendelian manner were still expressing the gene. Investigations into methylation of the stsgene showed that in three nonexpressing progenies inactivation was paralleled by methylation.  相似文献   

11.
The 5 flanking region of a salt-stress-inducible, CAM-specific phosphoenolpyruvate carboxylase (PEPC) gene from the facultative halophyte Mesembryanthemum crystallinum, was fused to the -glucuronidase (GUS) reporter gene and introduced into Nicotiana tabacum SR1. The Ppc1 promoter displayed high levels of expression in transgenic tobacco quantitatively and qualitatively similar to a full-length 35S CaMV-GUS construct. Histochemical assays revealed that the full-length Ppc1-GUS fusions expressed GUS activity in all tissues except in root tips. While tobacco is capable of utilizing the Ppc1 cis-acting regulatory regions from M. crystallinum to yield high levels of constitutive expression, this glycophyte fails to direct a stress-inducible pattern of gene expression typical of this promoter in its native, facultative halophytic host.  相似文献   

12.
Thiosulfate sulfurtransferase (TST) is an important ‘enzyme of protection,’ that accelerates the detoxification of cyanide, converting it into thiocyanate. The TST physiological rhythm was investigated at wks 2, 4, and 8 of post‐natal development (PND) in the mouse. The results revealed a statistically significant gender‐related difference, with the highest activity in females, at all the documented PND stages. In the second week of PND (pre‐weaning time), the circadian rhythm of the enzyme activity was associated with ultradian components. The prominent circadian rhythm (τ=24 h) peaked at the beginning of the light span, more precisely ~3 HALO (Hours After Light Onset). A week after weaning (wk 4 of PND), an impairment of the rhythm, with the peak shifted toward the second half of photophase, was recorded. Four to 6 wks later, about wk 8 of PND, the circadian rhythm pattern was stabilized, with its peak then located at the beginning of the dark span (13 HALO). The obtained results showed a 12 h phase‐shift of the circadian TST peak time during PND, suggesting that the rhythm stabilization is age‐dependent.  相似文献   

13.
Summary. We investigated the influence of hypothyroidism on homocysteine metabolism in rats, focusing on a hypothetical deficient synthesis of FAD by riboflavin kinases. Animals were allocated in control group (n=7), thyroidectomized rats (n=6), rats with diet deficient in vitamin B2, B9, B12, choline and methionine (n=7), thyroidectomized rats with deficient diet (n=9). Homocysteine was decreased in operated rats (2.6±1.01 vs. 4.05±1.0mol/L, P=0.02) and increased in deficient diet rats (29.56±4.52 vs. 4.05±1.0mol/L, P=0.001), when compared to control group. Erythrocyte-Glutathione-Reductase-Activation-Coefficient (index of FAD deficiency) was increased in thyroidectomized or deficient diet rats (P=0.004 for both). Methylenetetrahydrofolate-reductase and methionine-synthase activities were decreased in thyroidectomized rats but not in those subjected to deficient diet. Cystathionine--synthase was increased only in operated rats. Taken together, these results showed a defective re-methylation in surgical hypothyroidism, which was due in part to a defective synthesis of vitamin B2 coenzymes. This defective pathway was overcompensated by the increased Cystathionine--synthase activity.  相似文献   

14.
The combining region ofArtocarpus integrifolia lectin has been studied by using the ligand-induced changes in the fluorescence of the lectin. The saccharide binding properties of the lectin show that C-l, C-2, C-4, and C-6 hydroxyl groups of D-galactose are important loci for sugar binding. The -anorner of galactose binds more strongly than its -counterpart. Inversion in the configuration at C-4 as in glucose results in a loss of binding to the lectin. The C-6 hydroxyl group is also presumably involved in binding as D-fucose does not bind to the lectin.The lectin binds to the Thomsen-Friedenreich antigen (Gal(13)GalNAc) more strongly than the other disaccharides studied, viz. Gal/ (14) Gal and Gal (13) GlcNAc, which are topographically similar to T-antigen. This observation suggests that the combining region ofArtocarpus lectin is complementary to that of T-antigen.Solvent accessibility of the protein fluorophores have been probed by the quenching of protein fluorescence by Iodide ion in the absence and presence of sugar. In the presence of sugar a slight inaccessibility of the fluorophores to the solvent has been observed.Abbreviations MeGal 1-O-methyl--glucopyranoside - MeGal 1-O-methyl--glucopyranoside - GalNAc 2-acetamido-2-deoxy-galactose - Gal Galactose  相似文献   

15.
The murder of George Floyd sparked an awakening, long overdue, which reverberated throughout society. As science begins to acknowledge its role in perpetuating systematic racism, the voices of Black scientists, which have largely been absent, are now being called on. As we rightly begin to make space for diverse voices and perspectives in science, we all must think about what it is we are asking minoritized individuals to do.

It has been roughly 1 year since the murder of George Floyd, an unarmed Black man, who was killed over an alleged counterfeit 20 dollar bill in Minneapolis, Minnesota (Hill et al. 2020; Kaul, 2020; Levenson, 2021). In many ways, his murder was no different than the murders of thousands of other murders of Black people in this country (Thompson, 2020; Lett et al., 2021; Tate et al., 2021). However, what distinguishes George Floyd’s murder from many other high profile cases is that it was unambiguously captured on video (Alexander, 1994), an act of bravery by Darnella Frazier, a 17-year-old Black woman (Izadi, 2021), at a time when the world was mostly housebound by a raging global pandemic. As a result, his murder reverberated through society in a way that has not happened in my lifetime. While there have been other high profile cases of murders carried out by police (Treyvon Martin, Walter Scott, Breonna Taylor, and Philando Castile, among many others), these cases failed to fully sustain the attention of a national and international audience (Chan et al., 2020; Chughtai, 2021). The murder of George Floyd was fundamentally different, and for once, more than just Black people were paying attention. His murder sparked protests across the nation led by the Black Lives Matter (BLM) movement (Day, 2015; Taylor, 2016; Banks, 2018; Taylor, 2021), and the demands for change were so loud people could not help but hear.As a Black, gay man who is also a scientist, I was thrown into despair. All of my life I have thought if I just worked hard enough, if I am kind and unthreatening, if I play the game and keep my head down, maybe I can make it in academia. Maybe then I will be seen and accepted, not just by society, but by the scientific community. George Floyd’s murder reminded me, and many of my Black colleagues, that our degrees can’t protect us, that our privileged middle-class upbringing (if we had one) was not a shield. Our lives were not worth more than a counterfeit 20 dollar bill.Science, which has always been a product of society, was not impervious to these reverberations. By late June my inbox began to slowly fill with invitations to speak at several institutions for their seminar series, retreats, or special symposia. It felt as if the scientific community, for the first time, realized that there were Black scientists among them. In the throes of my own despair, and the feeling that I needed to be doing something for my community, I began to say “yes.” I was not going to participate in the nightly protests that occurred in my newly adopted hometown of Portland, Oregon. Aside from fearing I could be next to lose my life at the hands of the police (Edwards et al., 2019), these protests were happening in the backdrop of a global pandemic. I came to the conclusion that by accepting these invitations to speak, this could be my activism, my way of sparking change, increasing visibility, and being seen not only for my own sake but also for other Black scientists.Before I write anything else, I want to be clear: I am extremely thankful to all the institutions and organizations that invited me and gave me a platform. I am extremely proud of my students’ work and of the research we produce. I am sharing my experiences with the hope that they can be instructive to the greater scientific community, but if I am being frank, there is a bit of anger.I received over 15 invitations and gave an additional three or four interviews over the course of the year. Most of these came with the expectation that I would also talk about my work in Diversity, Equity, and Inclusion. But here’s the lowdown: prior to this year, I did not view myself as someone who did Diversity, Equity, and Inclusion work. I am co-chair of the LGBTQ+ committee of the American Society of Cell Biology and a member of the Diversity, Equity, and Inclusion committee of the Genetics Society of America. I volunteer for both of these committees because they speak to something I care deeply about, the advocacy for minoritized 1 scientists. I also embody both of these axes of diversity; so, in some way, I am only looking out for myself. This is far from being a scholar or doing “Diversity work.” I fully recognize that there are individuals who have dedicated their lives to this type of work with entire academic fields populated with accomplished scholars. So, I started this year of talks being invited because I am a Black, gay scientist at a time when science was grappling with its own systematic racism, under the guise of my nonexistent Diversity, Equity, and Inclusion work.What has this year actually taught me? The first thing it taught me is that I have been missing out. Prior to George Floyd’s murder, I had only received three seminar invitations from major research institutions and unfortunately all within a year of being posttenure. That is after nearly 6 years in my current position.In giving these talks I got the opportunity to meet with some of the giants in my field, people I have looked up to for years. I received reagents, offers to collaborate, and a litany of great ideas that will help drive my research program for years to come. I left some of these meetings truly inspired and excited to start experiments. These opportunities would have been invaluable to me, pretenure. One could argue, I did not need it. I made it even without this networking and the advantages these visits bring. Before you applaud my ability to persist and be resilient, we should take a deep look at the systems that have forced people who look like me to be doubly resilient. If George Floyd had not been murdered, would any of these invitations have happened? If the previous 6 years are any indication of a trend, I would have to say most certainly not. Why did it take a murder and the reignition of a Civil Rights movement for me to have the type of interactions I now know many of my straight, white counterparts have had from the very beginning of their independent careers? Let me be clear: this is a form of systematic racism, plain and simple.As I began to make the rounds, I was often asked to either share a bit of my journey or include my Diversity, Equity, and Inclusion work in my talks. This sometimes came at the expense of sharing my lab’s work. While I was very happy to do so, this was very much implicit in the invitations I received. At times it did feel that my inclusion was only checking a box, placating the graduate students so that they could see that their department or institution was responding to their demands. This also had the consequence of making me feel as though my science was merely performative. I was being invited to do the Diversity work institutions did not want to do. This is the tension I, and many other minoritized scientists, face. I want to share my experiences with the hopes that the next generation will have it better; but, my scholarly work is not in Diversity, Equity, and Inclusion. I fully recognize that it is my embodied diversity that is bringing me to the table; but, it is the science I want to share.On the first invitation to give a seminar, I promised myself that I was going to be honest. This meant that I would tell the truth about my experience and bare my soul over and over again. What I had not counted on was the emotional toll this would take on me. Reliving my own trauma, on a regular basis, left me emotionally drained after these visits. In one of my “stops” (I use quotes here because these “visits” were all virtual), I met with the queer, person of color (POC), graduate students. This session quickly turned into an emotional support group where I heard stories of mistreatment, racism, and discrimination. It was nearly impossible to maintain my composure. Diversity, Equity, and Inclusion work is clearly extremely important, but, maybe, we could just start by listening to the needs of the students and having a bit of humanity.The trial of Derek Chauvin has come and passed, and much to my surprise, and to the surprise of many other Black people nationwide, he was found guilty and was sentenced to prison (Arango, 2021; Cooper and Fiegel, 2021). This, of course, is not justice, not even close. Justice would mean that George Floyd is still alive and would get to live out his life in the way he chose. We are also at the beginning of the end of the pandemic. In 6 months or less, we may all be returning to life, more or less, as it was before George Floyd, before COVID-19. Does this mean we stop fighting? Does this mean that I, and many other Black scientists, suddenly disappear? For George Floyd, for countless other faceless Black people before him, I sincerely hope not. We need to continue to give Black scientists a platform. We need to ensure that they, too, are given the opportunity to network, collaborate, and interact with the larger scientific community. This means the invitations cannot stop. To further this, we need to ensure that Black scientists are included in every grant review panel, are included on speaker lists at every national and international meeting, are funded, and are in the room where funding, tenure, and other critical decisions are being made. We need to recognize that systematic racism has not gone away with Derek Chauvin’s conviction and sentencing. We need to continue to push forward. And, for all of you young, minoritized scientists (and allies) reading this, demand change and do not take "no" for an answer. I am truly sorry this has fallen on your shoulders, but enough is enough. The next generation of minoritized scientists should be recognized for their science without the additional burden of creating their own space.About the AuthorI am currently an Associate Professor of Biology at Reed College (https://www.reed.edu/biology/applewhite/index.html), which is located in Portland, Oregon. I arrived at Reed in 2014; prior to that, I was a postdoctoral fellow at the University of North Carolina, Chapel Hill. I received my PhD from Northwestern University in Cellular and Molecular Biology and a BS in Biology from the University of Michigan where I was also a 4-year letter winner in track and field. My research focuses on the cytoskeleton where I study cell motility and morphogenesis using Drosophila and Drosophila derived in tissue culture cells to explore actin, microtubules, and molecular motors. My current lab is composed of fierce, determined undergraduate students. I am a member of the American Society of Cell Biology (ASCB) and the current chair of the LGBTQ+ Committee (https://www.ascb.org/committee/lgbtq/). I am also a member of the Diversity, Equity, and Inclusion Committee for the Genetics Society of America (https://genetics-gsa.org/committees/). I also serve as an editor for MBoC’s Voices series.  相似文献   

16.
This is a personal account by a semi old-timer who completed his official term as a professor of plant biochemistry at Nagoya University in Japan in 1992. My university student life began soon after the World War II (1948). I shared the hardships of many in my age group, in that life was difficult during my college years. I was fortunate to have the opportunity of studying in the USA on a Fulbright scholarship first at Purdue University (1955–1956), and then at the University of California, Berkeley (1956–1957). My graduate study and postdoctoral training in the new world were vitally refreshing and stimulating, which gave me the impetus for becoming a natural scientist associated with academic institutions. Consciously and subconsciously I was impressed by the friendly and liberal atmosphere surrounding young students as well as senior scholars in the United States. But more importantly, I was inspired by the critical and competitive minds prevailing among these people.The appointment as a biochemist at the International Rice Research Institute (IRRI) in the Philippines (1962–1964) was the real start of my professional career. The work was continued upon my return to Nagoya to become a staff member of the Research Institute for Biochemical Regulation (1964–1992). Throughout the years, my major research interest has covered photosynthesis as a whole, involving photosynthetic CO2-fixation (RuBisCO), carbohydrate metabolism, e.g. starch biosynthesis and breakdown (-amylase), and metabolic regulation, which are interrelated in the basic metabolism of plant cells.I shall briefly describe in this article highlights from my studies and discoveries made and I shall also discuss their possible significance in plant metabolism, with the hope that it does not contradict my sense of humility: They are (a) discovery of ADPG in plants and its role in starch biosynthesis; (b) structure-function relationship of RuBisCO proteins, in particular on heterologous recombination of their subunits of plant-type enzyme molecules derived from the prokaryotic photosynthetic bacteria; (c) molecular evolution of RuBisCO genes; (d) mode of actions (formation, intracellular transport and secretion) of rice seed -amylase and its structural characteristics (distinctive glycosylation), and (e) DNA methylation and regulatory mechanism of photosynthesis gene expression in plastids (amyloplasts). In each step of my research, I shared joy, excitement, disappointment, and agony with my colleagues, an experience that may be common to all researchers. Although it is now becoming well recognized among the scientific community in Japan, I want to point out that interaction of multinational scientific minds in the laboratory produces a vital and creative atmosphere for performance of successful research. I experienced and realized this important fact in my earlier days in the USA and the Philippines. Inasmuch as I believe that this is the most crucial element for any research laboratory to possess, I fondly remember the friendships gained with numerous overseas visitors and collaborators who have contributed immensely to our work.Written at the invitation of Govindjee.  相似文献   

17.
Summary The angular dependence of1JC,H in model compounds related to -linked oligosaccharides has been established by FPT INDO quantum chemical calculations. Values calculated for models of (1 1)-, (1 2)-, (1 3)- and (1 4)-linked disaccharides were compared, and the effect of the orientation of HO-2 elucidated. The angular dependence of1JC,H on the torsional angles H and H and the solvent dielectric constant (s) was characterized in the form:1JC,H = A cos2+B cos + C sin2 + D since + E + Fe. The1JC,H values, measured by DEPT methods for C-1-H-1 and C-X-H-X in cellobiose, cyclic trisaccharide and hexopyranoses were used to adjust the calculated angular dependences. Based on the occurrence of the conformers for agarobiose, neoagarobiose, mannobiose and methyl -xylobioside, the thermodynamically averaged <1JC,H > values were calculated. The results obtained (<1JC-1,H-1 > 162.4, <1JC-4, H-4 > 147.6 Hz for methyl -xylobioside; <1JC-1,H-1 > 162.4 and <1JC-4,H-4] > 147.6 Hz for mannobiose; <1JC-1,H-1 > 162.8 Hz for neo agarobiose and <1JC-1,H-1 > 163.2 Hz for agarobiose) agree well with the experimental values of 162.7, 147.5, 160.4, 147.2, 160.9 and 165.7 Hz, respectively.  相似文献   

18.
Rhodococcus sp. I24 can oxygenate indene via at least three independent enzyme activities: (i) a naphthalene inducible monooxygenase (ii) a naphthalene inducible dioxygenase, and (iii) a toluene inducible dioxygenase (TID). Pulsed field gel analysis revealed that the I24 strain harbors two megaplasmids of 340 and 50 kb. Rhodococcus sp. KY1, a derivative of the I24 strain, lacks the 340 kb element as well as the TID activity. Southern blotting and sequence analysis of an indigogenic, I24-derived cosmid suggested that an operon encoding a TID resides on the 340 kb element. Expression of the tid operon was induced by toluene but not by naphthalene. In contrast, naphthalene did induce expression of the nid operon, encoding the naphthalene dioxygenase in I24. Cell free protein extracts of Escherichia coli cells expressing tidABCD were used in HPLC-based enzyme assays to characterize the indene bioconversion of TID in vitro. In addition to 1-indenol, indene was transformed to cis-indandiol with an enantiomeric excess of 45.2% of cis-(1S,2R)-indandiol over cis-(1R,2S)-indandiol, as revealed by chiral HPLC analysis. The Km of TID for indene was 380 M. The enzyme also dioxygenated naphthalene to cis-dihydronaphthalenediol with an activity of 78% compared to the formation of cis-indandiol from indene. The Km of TID for naphthalene was 28 M. TID converted only trace amounts of toluene to 1,2-dihydro-3-methylcatechol after prolonged incubation time. The results indicate the role of the tid operon in the bioconversion of indene to 1-indenol and cis-(1S,2R)-indandiol by Rhodococcus sp. I24.  相似文献   

19.
In this study we investigated the effect of the cytokines human granulocyte/macrophage-colony-stimulating Factor (hGM-CSF) and interferon (IFN) on human Kupffer-cell-mediated cytotoxicity against the SW948 coloncarcinoma cell line. Kupffer cells were isolated from small liver wedge biopsies, taken from 14 patient who had had abdominal surgery for colon carcinoma or partial hepatectomy. The cells were incubated with hGM-CSF (100 ng/ml), or with IFN (100 U/ml) or with their combination and the perecentage cytotoxicity was determined using a recently described modified assay. Additional experiments were performed with tumour-necrosis-factor-(TNF)-sensitive U937 cells as target. The TNF secretion of Kupffer cells was measured and we evaluated the effect of TNF on colon tumour targets. We performed human-Kupffer cell-mediated cytotoxicity blocking experiments with anti-TNF and used paraformaldehydefixed Kupffer cells to demonstrate lysis of TNF-sensitive WEHI-164 cells and of SW948 cells. The overall cytotoxicity against SW948 caused by unactivated Kupffer cells (n=14), and by Kupffer cells activated with hGM-CSF (n=14), IFN (n=6) or their combination (n=6) was respectively: 19.5±2.6%, 25.3±2.9% 41±9.4% and 45.6±8% at E/T=1 and 28.2±2.9%, 35.6±3.2%, 55.6±9.7% and 62.8% at E/T=5. All differences were statistically significant (P<0.05). No growth-promoting activity by hGM-CSF on the SW948 tumour cells was observed. U937 cells were highly susceptible to Kupffer-cell-mediated cytotoxicity. The TNF secretion by human Kupffer cells increased in parallel to their cytotoxicity after incubation with these cytokines. Soluble TNF had only a slight anti-proliferative effect on SW948 cells, while specific anti-TNF blocked Kupffer cell cytotoxicity by up to 80%. Finally, paraformaldehyde-fixed Kupffer cells were able to lyse WEHI-164 and SW948 cells. This indicates that expression of cell-associated TNF is the main cytolytic mechanism of human-Kupffer-cell-mediated cytotoxicity. The implications for the use of hGM-CSF and IFN in vivo are discussed.  相似文献   

20.
Summary Catalytic activities of -chymotrypsin and subtilisin Carlsberg for transesterification of N-acetyl-L-tyrosine methyl ester in ethanol markedly increased by decreasing the amount of the enzymes in the reaction mixtures. The results were kinetically attributed to changes in KM and kcat due to formation of smaller enzyme aggregates.  相似文献   

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