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1.
A method is described whereby arrays of samples ofClupea pallasi eggs may be stored during their preparation. The high fertilization potential retained by the eggs during short-term storage allows them to be fertilized synchronously when sample preparation is complete. A variation of the dry method of storage retained maximum fertilization potential (80–85%) of the eggs for about 1 hr, and of milt dilution (18 with 17 S sea water), about 7 hr. Following dry storage, eggs fertilized in salinities of 0–45 showed maximum rates of fertilization in salinities of 10–20, and fertilization rates 50% in salinities of 4.5–42. Salinities of fertilization influenced egg diameter, median hatching time, and larval length at hatching in egg samples transferred 21/2 hr after fertilization to an incubation salinity of 17 at 7°C. Fertilization rates were higher (90–95%) for eggs stored in 17 S at 7°C prior to fertilization. Under such wet storage conditions, maximum fertilization pontential was retained for about 2 hr. Highest fertilization rates (95–96%) were obtained for eggs stored and fertilized in salinities of 12–15. For the species and the area of origin considered (British Columbia), wet storage of eggs should result in maximum fertilization when the eggs are stored at 4°C for a period not greater than 2 hr prior to fertilization in the 12–15 S storage medium.Prepared under the auspices of the Canadian-German Scientific and Technical Cooperation Agreement.  相似文献   

2.
The stable isotope ratios of nitrogen were measured in the mysid,Neomysis intermedia, together with various biogenic materials in a eutrophic lake, Lake Kasumigaura, in Japan throughout a year of 1984/85. The mysid, particulate organic matter (POM, mostly phytoplankton), and zooplankton showed a clear seasonal change in 15N with high values in spring and fall, but the surface bottom mud did not. A year to year variation as well as seasonal change in 15N was found in the mysid. The annual averages of 15N of each material collected in 1984/85 are as follows: surface bottom mud, 6.3 (range: 5.7–6.9); POM, 7.9 (5.8–11.8); large sized mysid, 11.6 (7.7–14.3); zooplankton, 12.5 (10.0–16.4); prawn, 13.2 (9.9–15.4); goby, 15.1 (13.8–16.7). The degree of15N enrichment by the mysid was determined as 3.2 by the laboratory rearing experiments. The apparent parallel relationship between the POM and the mysid in the temporal patterns of 15N with about 3 difference suggests the POM (mostly phytoplankton) as a possible food source ofN. intermedia in this lake through the year.  相似文献   

3.
Ray  I.  Chauhan  A.  Wisniewski  H. M.  Wegiel  J.  Kim  K. S.  Chauhan  V. P. S. 《Neurochemical research》1998,23(10):1277-1282
Amyloid beta-protein (A), in its soluble form, is known to bind several circulatory proteins such as apolipoprotein (apo) E, apo J and transthyretin. However, the binding of A to intracellular proteins has not been studied. We have developed an overlay assay to study A binding to intracellular brain proteins. The supernatants from both rat and human brains were found to contain several proteins that bind to A 1–40 and A 1–42. No major difference was observed in the A binding-proteins from brain supernatants of patients with Alzheimer's disease and normal age-matched controls. Binding studies using shorter amyloid beta-peptides and competitive overlay assays showed that the binding site of A to brain proteins resides between 12–28 amino acid sequence of A. The presence of several intracellular A-binding (AB) proteins suggests that these proteins may either protect A from its fibrillization or alternatively promote A polymerization. Identification of these proteins and their binding affinities for A are needed to assess their potential role in the pathogenesis of Alzheimer's disease.  相似文献   

4.
Strain H-984 of G. fujikuroi grown for 38h in a shake flask with medium containing 20g glucose l–1, 3g yeast extract l–1, 2.5g NH4NO3 l–1, 0.5g KH2PO4 l–1, 0.1g MgSO4 l–1, 1g CaCO3 l–1, and inoculated into a bioreactor with medium containing 60g glucose l–1; 1g NH4Cl l–1; 3g KH2PO4 l–1 and 1.5g MgSO4 l–1 produced 1100mg gibberellic acid l–1.  相似文献   

5.
Summary Detailed restriction enzyme analysis of the DNA from a Chinese female showed that one of her chromosomes had a >17.5 kb deletion of DNA, including the , 2, and 1 globin genes, which is present in many Southeast Asians with an -thalassemia-1 chromosome. Her normal chromosome had the expected cluster of -like globin genes (5----2-1-3), but the segment of DNA between the two globin genes was elongated by some 0.5–0.7 kb. Analyses of various restriction sites suggested that this normal variant of the human globin gene complex is due to a crossover between a normal chromosome with () and a chromosome with an -thalassemia-2 (–3.7) and an -21-hybrid gene.  相似文献   

6.
Three strains ofClostridium butyricum exhibited elevated minimal inhibitory concentrations (MICs) to penicillin (64–1,024 g/ml), ampicillin (32–256 g/ml), carbenicillin (128–1,024 g/ml), and oxacillin (32–64 g/ml). Cephalosporin/cephamycin agents were more active than penicillin drugs. All isolates were found to possess a -lactamase. The -lactamases were primarily cell associated during the logarithmic phase of growth. Stationary-phase cells released most of the enzyme into the culture medium. Cephalothin supplementation of broth cultures with concentrations equivalent to one-eighth of the MIC significantly increased the quantity of -lactamase synthesized. The -lactamases produced by these three isolates exhibited greatest activity with penicillin followed by ampicillin>cephaloridine>carbenicillin and oxacillin. No enzymatic activity was observed using cephalothin, cephalexin, cefazolin, cefoxitin, or cephamandole substrates. The -lactamases were inhibited by clavulanic acid and para-chloromurcuribenzoate and not inhibited by cloxacillin. Each enzyme exhibited an isoelectric point of 4.2.  相似文献   

7.
This paper is about power, medicine andthe identity of the African as a patient of westernmedicine. From a conventional perspective and asencoded in the current quest for wholeness thatcharacterises South African biomedical discourse, theAfrican patient – like any other patient – has alwaysexisted as an authentic and subjectified being, whosetrue attributes and experiences have been denied bythe mechanistic, reductionistic and ethnocentricpractices of clinical medicine. Against this liberalhumanist perspective on the body as ontologicallyindependent of power, this paper offers a Foucaultianreading of the African patient as – like any otherpatient – contingent upon the force relations immanentwithin and relayed through the clinical practices ofbiomedicine. A quintessential form of disciplinarymicro-power, these fabricate the most intimaterecesses of the human body as manageable objects ofmedical knowledge and social consciousness to makepossible the great control strategies of repression,segmentation and liberation that are the usual focusof conventional investigations into the place andfunction of medicine in society. Since the 1930s whenthe African body first emerged as a discrete object ofa secular clinical knowledge, these have repeatedlytransformed the attributes and identity of the Africanpatient, and the paper traces this archaeology ofSouth African clinical perception from then until the1990s to show how its quest for wholeness is not anend point of discovery or liberation, but merelyanother ephemeral crystallization of socio-medicalknowledge in a constantly changing force field ofdisciplinary power.  相似文献   

8.
Amyloid protein is the major protein component of neuritic plaques found in the brain of Alzheimer's disease. The activation of phospholipase D by amyloid beta protein (25–35), quisqualate and phorbol 12, 13-dibutyrate was investigated in LA-N-2 cells by measuring phosphatidylethanol formation. The activation of phospholipase D by quisqualate and AP (25–35) was calcium-independent. The AP (25–35) and quisqualate activation of phospholipase D appeared to be mediated through a pertussis toxin-sensitive GTP-binding protein. Phospholipase D activation by AP (25–35), quisqualate and phorbol dibutyrate was not blunted by the protein kinase C inhibitors, staurosporine, H-7 and RO-31-8220. However, it was abolished by overnight exposure to phorbol dibutyrate. This activation of phospholipase D was prevented by the tyrosine kinase inhibitor, genistein but not by tyrophostin A. Several excitatory amino acid antagonists were tested for their ability to prevent the phospholipase D activation by quisqualate and AP (25–35). Only NBQX was effective with an IC50 of 75 M for AP (25–35) and quisqualate. Activation of phospholipase D by AP or quisqualate was absent in LA-N-2 cells previously desensitized by quisqualate or AP (25–35), but the activation by phorbol dibutyrate was unaltered. The responsiveness to AP and quisqualate in previously desensitized cells reappeared subsequent to a period of resensitization. The observations with the antagonist NBQX, and the desensitization and resensitization experiments, are consistent with a receptor occupancy mediated activation of phospholipase D by quisqualate and by AP (25–35).  相似文献   

9.
Psychological parameters of mental activity (30 in total) and their genetic determination were studied in 67 families of schizophrenia patients (67 patients, 107 parent, and 30 sibs). Abnormalities of most of the examined characteristics were found in both the patients and their healthy relatives. Parameters of attention shifting and emotionality revealed the largest genetic component (25–75 and 17–98%, respectively) in all analyzed groups of relatives (probands–affected sibs, probands–healthy sibs, healthy parents–healthy children, affected parents–affected children). Significant impact of genetic factors was also found in parameters stability of attention under conditions of continuous concentration, mediated retention span productivity of voluntary retention by reproduction data, personal anxiety level, reflection of unusual social groups, and self-assessment. The relationships among the characteristics examined in the system of mental activity were established by means of cluster analysis. The results of this study can be used in medical genetic counseling for identifying subjects at high risk for schizophrenia.  相似文献   

10.
This study examined macronutrient input from pollen in two naturally regenerating pine stands in southeast Korea. Durham gravity pollen collectors were used to measure pine pollen deposition and the macronutrients in the collected pine pollen were analyzed. In 1998, pine pollen deposition began just before 18 April and lasted for approximately 2weeks. Total pine pollen deposition differed between the two sampling sites; 27.5kgha–1 was collected from the mature stand and 17.7kgha–1 was collected from the young stand. The values for nutrient deposition from pine pollen are 549gha–1 N, 78gha–1 P, 240gha–1 K, 45gha–1 S and 22gha–1 Mg at the mature stand and 353gha–1 N, 51gha–1 P, 151gha–1 K, 27gha–1 S and 14gha–1 Mg at the young stand, suggesting that nutrients from pine pollen contribute to forest nutrient cycling. The pine pollen deposition values obtained from our study (17.7–27.5kg–1ha–1year–1) are approximately 1/115–180-fold that of pine litterfall in Korea. If we take pollen nutrients into account, the contribution rate of pollen to the annual nutrient input is very high in our study (N 1/30, P 1/5, K 1/9 that of litterfall). Macronutrient deposition from pine pollen is concentrated temporally in spring. Although the annual contribution of nutrient mass by pollen is small compared to that of litterfall, the rapid turnover rate of pollen nutrients combined with episodic deposition suggests that pollen may play a disproportionate role in temperate pine forest nutrient cycling.  相似文献   

11.
Stable carbon (13C) and nitrogen (15N) isotopes were used to elucidate primary food sources and trophic relationships of organisms in Khung Krabaen Bay and adjacent offshore waters. The three separate sampling sites were mangroves, inner bay and offshore. The 13C values of mangrove leaves were –28.2 to –29.4, seagrass –10.5, macroalgae –14.9 to –18.2, plankton –20.0 to –21.8, benthic detritus –15.1 to –26.3, invertebrates –16.5 to –26.0, and fishes –13.4 to –26.3. The 15N values of mangrove leaves were 4.3 to 5.7, seagrass 4.3, macroalgae 2.2 to 4.4, plankton 5.7 to 6.4 , benthic detritus 5.1 to 5.3, invertebrates 7.2 to 12.2 , and fishes 6.3 to 15.9. The primary producers had distinct 13C values. The 13C values of animals collected from mangroves were more negative than those of animals collected far from shore. The primary carbon sources that support food webs clearly depended on location. The contribution of mangroves to food webs was confined only to mangroves, but a mixture of macroalgae and plankton was a major carbon source for organisms in the inner bay area. Offshore organisms clearly derived their carbon through the planktonic food web. The 15N values of consumers were enriched by 3–4 relative to their diets. The 15N data suggests that some of aquatic animals had capacity to change their feeding habits according to places and availability of foods and as a result, individuals of the same species could be assigned to different trophic levels at different places.  相似文献   

12.
Nucleation-dependent protein aggregation (seeding) and amyloid fibril-free formation of soluble SDS-resistant oligomers (oligomerization) by hydrophobic interaction is an in vitro model thought to propagate -amyloid (A) deposition, accumulation, and incur neurotoxicity and synaptotoxicity in Alzheimers disease (AD), and other amyloid-associated neurodegenerative diseases. However, A is a high-affinity metalloprotein that aggregates in the presence of biometals (zinc, copper, and iron), and neocortical A deposition is abolished by genetic ablation of synaptic zinc in transgenic mice. We now present in vitro evidence that trace (0.8 µM) levels of zinc, copper, and iron, present as common contaminants of laboratory buffers and culture media, are the actual initiators of the classic A1–42-mediated seeding process and A oligomerization. Replicating the experimental conditions of earlier workers, we found that the in vitro precipitation and amyloidosis of A1–40 (20 µM) initiated by A1–42 (2 µM) were abolished by chelation of trace metal contaminants. Further, metal chelation attenuated formation of soluble A oligomers from a cell-free culture medium. These data suggest that protein self-assembly and oligomerization are not spontaneous in this system as previously thought, and that there may be an obligatory role for metal ions in initiating A amyloidosis and oligomerization.  相似文献   

13.
The present study demonstrates a procedure for the rapid development of a high number of somatic embryos from embryogenic suspension culture. This method might be efficient for mass propagation of Phnix dactylifera L. Embryogenic callus placed in liquid medium with 10–5M ABA yielded an average 72 embryos per 100ml of culture medium within 2months, while those placed on solid medium yielded an average of 33, 20 and 16 embryos per 100ml of culture medium respectively for 10–7, 10–6 and 10–5 M ABA after 4months. The combination of 2,4-DIchlorophenoxyacetic acid (2,4-D) (4.5×10–7M), glutamine (6.7×10–4M), and ABA (10–5M) (L8 liquid medium) showed a beneficial effect on somatic embryos production compared to 2,4-D and glutamine alone, while this combination significantly (p<0.05) increased the accumulation of storage proteins (144 and 138mgg–1 DW respectively for Jihel and Bousthami noir cultivars) in somatic embryos. The somatic embryos which underwent maturation on medium containing only 4.5×10–7M 2,4-D and 10–5M ABA (L6 liquid medium) accumulated more sugars (292 and 265mgg–1 DW respectively for Jihel and Bousthami noir) than those matured on any other liquid medium. Histological studies revealed that somatic embryos (developed in L6 and L8 liquid media) accumulated less reserve compounds (proteins and sugars) than zygotic embryos. The addition of activated charcoal (0.25 and 0.5gl–1) and phytagel® (2.5gl–1) to the germination medium may be useful for enhancing the germination of Phnix dactyliferasomatic embryos.  相似文献   

14.
TNF alpha is required for hypoxia-mediated right ventricular hypertrophy   总被引:1,自引:0,他引:1  
Hypoxia has been shown to activate the pleiotropic cytokine TNF in the lung. TNF in turn, is known to induce pulmonary vasoconstriction. Additional effects of this cytokine in hypoxia mediated cardiopulmonary remodeling are poorly understood. To further evaluate the role of TNF in chronic hypoxia we exposed TNF null (TNF–/–) and wild-type mice to three weeks of hypobaric hypoxia (10% O2). Equivalent erythocytosis (Hematocrit increased by 40%) developed in both genetic backgrounds. In contrast, right ventricular systolic pressure increased in response to three weeks of hypoxia in the wild-type mice ( 75%), yet was unaltered in the TNF–/– mice. Concomitantly right ventricular hypertrophy was attenuated in the TNF–/– mice (35 ± 5% increase) when compared to wild-type mice (124 ± 6% increase p < 0.001, n 20). Interestingly in both strains the lung wet weights increased to a similar degree in response to hypoxia. In conclusion, our data demonstrate that TNF is an integral autocoid in chronic hypoxia mediated right ventricular hypertrophy. Moreover, additional components of cardiopulmonary remodeling may be regulated by TNF signaling as suggested by the negligible right ventricular systolic pressure response to hypoxia in the absence of TNF.  相似文献   

15.
The Zn(II) binding by partial peptides of human protamine HP2: HP21–15; HP21–25, HP226–40, HP237–47, and HP243–57 was studied by circular dichroism (CD). Precipitation of a 20mer DNA by these partial peptides and the effects of Zn(II) thereon were investigated using polyacrylamide gel electrophoresis (GE). The results of this study suggest that reduced HP2 (thiol groups intact) can bind Zn(II) at various parts of the molecule. In the absence of DNA, the primary Zn(II) binding site in reduced HP2 is located in the 37–47 sequence (involving Cys37, His39, His43, and Cys47), while in the presence of DNA, the strongest Zn(II) binding is provided by sequences 12–22 (by His12, Cys13, His19, and His22) and 43–57 (His43, Cys47, Cys53, and His57). In its oxidized form, HP2 can bind zinc through His residues of the 7–22 sequence. Zn(II) markedly enhances DNA binding by all partial peptides. These findings suggest that Zn(II) ions may be a regulatory factor for sperm chromatin condensation processes.  相似文献   

16.
Summary The effect of a non-indole compound, phenylacetic acid (PAA), on the induction of somatic embryogenesis in tissue cultures of geranium (Pelargonium x hortorum Bailey cv. Scarlet Orbit Improved) was investigated. Hypocotyl explants derived from young, dark-grown seedlings were cultured on Murashige and Skoog (1962) medium (MS) supplemented with PAA or IAA (0.01–120 M) alone or in combination with BAP (8 M). Somatic embryogenesis was induced by both PAA and IAA at 0.01–20 M with 8 M BAP, however, the optima differed considerably for the two compounds. Maximal activity of IAA for somatic embryogenesis was found at 0.1–2.5 M, whereas PAA gave best results at 10 and 20 M under identical culture conditions. Higher concentrations (30–120 M) of IAA or PAA in the medium induced callusing in the explants, but the callus was neither embryogenic nor morphogenic.Abbreviations BAP N6-benzylaminopurine - IAA indole-3-acetic acid - MS Murashige and Skoog (1962) - PAA phenylacetic acid  相似文献   

17.
Interaction of topotecan (TPT) with synthetic double-stranded polydeoxyribonucleotides has been studied in solutions of low ionic strength at pH 6.8 by linear flow dichroism (LD), circular dichroism (CD), UV-Vis absorption, and Raman spectroscopy. The complexes of TPT with poly(dG-dC)·poly(dG-dC), poly(dG)·poly(dC), poly(dA-dC)·poly(dG-dT), and poly(dA)·poly(dT), as well as complexes of TPT with calf thymus DNA and coliphage T4 DNA studied by us previously, have been shown to have negative LD in the long-wavelength absorption band of TPT, whereas the complex of TPT with poly(dA-dT)·poly(dA-dT) has positive LD in this absorption band of TPT. Thus, there are two different types of TPT complex with the polymers. TPT has been established to bind preferably to GC base pairs because its affinity to the polymers of different composition decreases in the following order: poly(dG-dC)·poly(dG-dC) > poly(dG)·poly(dC) > poly(dA-dC)·poly(dG-dT) > poly(dA)·poly(dT). The presence of DNA has been shown to shift the monomer–dimer equilibrium in TPT solutions toward dimer formation. Several duplexes of the synthetic polynucleotides bound together by bridges of TPT dimers may participate in the formation of the studied type of TPT–polynucleotide complex. Molecular models of TPT complex with linear and circular supercoiled DNAs and with deoxyguanosine have been considered. TPT (and presumably the whole camptothecin family) proved to represent a new class of DNA-specific ligands whose biological action is associated with formation of dimeric bridges between two DNA duplexes.  相似文献   

18.
Fallisia biporcati n. sp. parasitises thrombocytes and lymphocytes of Anolis biporcatus and A. lionotus in Panama. Round or oval schizonts average 13.3 × 11.5 (10.5–16 × 9–13) m, with LW 153.8 (94–208) m2, and produce 38.3 (28–60) merozoites. Gametocytes are variably shaped, from round or oval to nearly triangular or rectangular, and average 12.6 × 9.0 (10–15 × 6–12) m, with LW 113.1 (82–150) m2 and L/W ratio 1.43 (1.0–2.2). Thrombocytes and lymphocytes of A. poecilopus in Panama are parasitised by F. poecilopi n. sp. Schizonts, oval to elongate in shape, 7.7 × 4.7 (5.5–9 × 3–6) m, with LW 36.5 (22–54) m2, are filled with 31.0 (20–51) tiny nuclei or merozoites. Gametocytes are 10.1 × 8.0 (7.5–14 × 6–11) m, with LW 82.0 (45–132) m2, round to elongate with L/W ratio 1.27 (1.0–1.6). F. thecadactyli n. sp. parasitises thrombocytes and lymphocytes of Thecadactylus rapicaudus in Panama and Venezuela. Oval, oblong, or triangular schizonts average 10.3 × 8.0 (7–13 × 5–12) m, with LW 86.6 (37–156) m2, and produce 40.2 (26–61) merozoites. Gametocytes are round, oval, triangular or elongate, 10.4 × 7.0 (7–15 × 5–11) m, with LW 74.8 (40–154) m2 and L/W ratio 1.51 (1.1–2.2). F. dominicensis n. sp. parasitises thrombocytes of A. cybotes on Hispaniola. Schizonts, 6.0 × 4.8 (4–8 × 3–7) m, with LW 29.1 (12–56) m2, round, oval, elongate, oblong or lentiform in shape, produce 12.4 (8–22) merozoites. Gametocytes are 6.6 × 5.0 (5–9 × 4–7) m , with LW 33.8 (20–56) m2, round, oval or elongate, and L/W ratio of 1.34 (1.1–2.0).  相似文献   

19.
DNA regions undergoing programmed repair synthesis during pachytene were isolated and used as a probe for analyzing the organization of these regions. Segments that are the sites of nick-repair activity are referred to as PsnDNA. These segments are distributed at intervals ranging from 30–350 kilobase pairs (kbp) within about half the genome. The other half of the genome, which consists of DNA molecules longer than 350 kbp under defined conditions of extraction, lacks these segments. PsnDNA sequences range in length from about 150–300 base pairs (bp) and are arranged in larger P.DNA units measuring 0.8–3.0 kbp. P.DNA units have three identifiable regions. Each end region consists of a PsnDNA sequence and the middle region contains sequences that do not share homology with PsnDNA and have a much lower repeat number. Pachytene nicking of PsnDNA sequences is polar with respect to the orientation of individual DNA strands. Most of the PsnDNA sequences are present at the 5 ends of the single strands generated in vivo by endonuclease action. Nicking is probably repeated at each PsnDNA site during early and midpachytene, and both members of a duplex are nicked within any single P.DNA region.  相似文献   

20.
DNA polymorphism patterns linked to the A-globin gene were analyzed in healthy Japanese using four different restriction endonucleases. The chromosomes with the A-globin gene were mapped through an evaluation of the presence of seven different restriction sites (HincII 5 to ; HindIII in G and A; HincII in, and 3 to, 1; AvaII in ; Bam-HI 3 to ). Among 36 chromosomes analyzed, 20 chromosomes had a haplotype of [+–––––+]. Among 55 individuals examined, 7 possessed a homozygous haplotye of [+–––––+]. All Japanese with the AT-globin gene had a subhaplotype of [–++–+] 5 to the -globin gene. Their major haplotypes were [–++–+–+] and [–++–++–]. It was expected that the presence of the AT-globin gene in Japanese may be deduced from subhaplotypes 5 to the -globin gene.  相似文献   

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