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1.
The roseringed parakeet has been shown to exhibit a variable testicular responsiveness to both altered photoperiodic regimens and to treatment with melatonin during different phases of the annual gonadal cycle. Adult male roseringed parakeets were held under either natural photoperiods (NP), or long photoperiods (LP; 16L 8D), or short photoperiods (SP; 8L 16D) for a total period of 90 days. From day 46 onward, half of the total birds in each group were administered with the vehicle of melatonin, and the other birds were injected daily in the afternoon with melatonin (25 µg/ 100 g body wt.) till the end of the experiment. An identical experimental schedule was followed during the four different (preparatory, progressive, pre-breeding, and breeding) phases of the annual testicular cycle. The testicular activities in various bird groups were evaluated by volumetric, gravimetric, histometric and karyometric measurements, and by quantitative histological studies. The findings revealed that exogenous melatonin may exert either a suppressive influence or none at all on the testicular functions in relation to the photoperiodic schedule as well as to the reproductive phase of the concerned bird, but in no case modulates gonadal responsiveness to artificially altered photoperiods. 相似文献
2.
Anamika Sengupta 《Chronobiology international》2013,30(5):915-933
The role of the pineal gland and its hormone melatonin in the regulation of annual testicular events was investigated for the first time in a psittacine bird, the roseringed parakeet (Psittacula krameri). Accordingly, the testicular responsiveness of the birds was evaluated following surgical pinealectomy with or without the exogenous administration of melatonin and the experimental manipulations of the endogenous levels of melatonin through exposing the birds to continuous illumination. An identical schedule was followed during the four reproductive phases, each characterizing a distinct testicular status in the annual cycle, namely, the phases of gametogenic quiescence (preparatory phase), seasonal recovery of gametogenesis (progressive phase), seasonal initiation of sperm formation (pre‐breeding phase), and peak gametogenic activity (breeding phase). In each reproductive phase, the birds were subjected to various experimental conditions, and the effects were studied comparing the testicular conditions in the respective control birds. The study included germ cell profiles of the seminiferous tubules, the activities of steroidogenic enzymes 17β‐hydroxysteroid dehydrogenase (17β‐HSD), and Δ53β‐hydroxysteroid dehydrogenase (Δ53β‐ HSD) in the testis, and the serum levels of testosterone and melatonin. An analysis of the data reveals that the pineal gland and its hormone melatonin may play an inhibitory role in the development of the testis until the attainment of the seasonal peak in the annual reproductive cycle. However, in all probability, the termination of the seasonal activity of the testis or the initiation of testicular regression in the annual reproductive cycle appears to be the function of the pineal gland, but not of melatonin. 相似文献
3.
This study demonstrates that under subtropical environmental conditions the circulating levels of triiodothyronine (T 3 ) and thyroxine (T 4 ) in adult male roseringed parakeets undergo parallel changes according to a diurnal cycle with a trough in the early morning and a peak in the evening. Chronic afternoon administration of melatonin (25 µg/ 100 g body wt./ day for 30 consecutive days) abolishes time-bound changes in the concentrations of T 3 by suppressing its evening peak, but does not abolish the diurnal rhythm of T 4 . Exogenous melatonin, however, causes a significant increase in the evening value of serum T 4 and a decrease in its value at midnight resulting in phase-shifting of the diurnal fluctuations of T 4 compared to that in the control birds. It appears that exogenous melatonin can alter the diurnal profiles of serum thyroid hormones in a wild psittacine bird. 相似文献
4.
This study demonstrates that under subtropical environmental conditions the circulating levels of triiodothyronine (T 3) and thyroxine (T 4) in adult male roseringed parakeets undergo parallel changes according to a diurnal cycle with a trough in the early morning and a peak in the evening. Chronic afternoon administration of melatonin (25 µg/ 100 g body wt./ day for 30 consecutive days) abolishes time-bound changes in the concentrations of T 3 by suppressing its evening peak, but does not abolish the diurnal rhythm of T 4. Exogenous melatonin, however, causes a significant increase in the evening value of serum T 4 and a decrease in its value at midnight resulting in phase-shifting of the diurnal fluctuations of T 4 compared to that in the control birds. It appears that exogenous melatonin can alter the diurnal profiles of serum thyroid hormones in a wild psittacine bird. 相似文献
5.
Abstract Adult male roseringed parakeets were transferred to 16L: 8D (LP), or 8L: 16D (SP) for 45 or 90 days on four particular dates corresponding to the different phases of an annual testicular cycle and the cytological responses of the pineal were studied comparing them with the features in respective natural photoperiodic (NP) birds. Different cytological characteristics including the values of nuclear diameter in pinealocytes indicated that LP for 45 days during the pre‐breeding phase and for 90 days during each phase resulted in an increased pineal activity, while SP for 45 and 90 days induced inhibitory responses of the pineal during each, but not the progressive phase of the annual testicular cycle. During the latter phase, none of the artificial photoperiodic schedules, other than LP for 90 days, influenced the cytological features of the pineal. The results suggest that the photosensitivity of the pineal in these parakeets varies in relation to the testicular functions in an annual testicular cycle, but the seasonal pattern of photoperiodic response of the pineal and that of the previously studied testes in the same birds does not seem to be identical. 相似文献
6.
Maya Shedpure 《Biological Rhythm Research》1999,30(3):297-312
Studies were planned to elucidate if the pineal plays any part in the regulation of protein contents in the serum and tissues of an Indian freshwater catfish, Clarias batrachus . In addition, an attempt has been made to investigate the modulatory roles of the status of thyroid and testis by using two potent inhibitors, i.e. iopanoic acid (thyroid inhibitor) and cyproterone acetate (androgen inhibitor). The results suggest that in general, the effects of the pineal and melatonin on protein content of serum and muscle and liver tissues are mediated with the involvement of the gonads. In addition, the thyroid status modulated the effects of pinealectomy on liver and muscle protein. 相似文献
7.
Maya Shedpure 《Biological Rhythm Research》2013,44(3):297-312
Studies were planned to elucidate if the pineal plays any part in the regulation of protein contents in the serum and tissues of an Indian freshwater catfish, Clarias batrachus. In addition, an attempt has been made to investigate the modulatory roles of the status of thyroid and testis by using two potent inhibitors, i.e. iopanoic acid (thyroid inhibitor) and cyproterone acetate (androgen inhibitor). The results suggest that in general, the effects of the pineal and melatonin on protein content of serum and muscle and liver tissues are mediated with the involvement of the gonads. In addition, the thyroid status modulated the effects of pinealectomy on liver and muscle protein. 相似文献
8.
In the present investigation, daily variations in plasma levels of melatonin, testosterone and estradiol-17β were analysed in the tropical freshwater catfish, Clarias batrachus during early and late-preparatory, pre-spawning, late-spawning and post-spawning phases of its annual reproductive cycle. Plasma melatonin levels exhibited a significant circadian rhythm during all the reproductive phases but peaks were invariably at night. The amplitude of melatonin was high during the early-preparatory phase and low in the pre-spawning phase. Testosterone also displayed significant rhythm during all the studied phases except post spawning phase. Estradiol-17β revealed diurnal rhythm only during preparatory and pre-spawning phases. The peak in the levels of plasma testosterone and estradiol-17β were recorded during the photophase. During the late-preparatory phase, the rhythm of testosterone coincided with the rhythm of estradiol-17β. 相似文献
9.
N. E. Makarchouk K. Yu. Maksimovich V. I. Kravchenko S. A. Kryzhanovskii 《Neurophysiology》2011,42(5):362-370
We studied modifications of EEG activity related to perception of visual stimuli (pictures) of the International Affective Picture System (IAPS) in women during different phases of the ovulatory (menstrual) cycle. We found that the woman’s brain is most intensely activated by both emotionally negative and positive visual stimuli during the follicular phase of the ovulatory cycle, while such activation is minimum during ovulation per se. Upon the action of neutral stimuli, cerebral activation was the most intense during the lutein phase (compared with that within other phases); manifestations of activation were concentrated in the right hemisphere. Cognitive and emotional components of perception of affective pictures were expressed to a greatest extent in the course of viewing positive stimuli during the follicular phase. Perception of emotionally pleasant stimuli during other phases was accompanied by lateralization of activation of sensory and analytical processes in the left hemisphere during the ovulatory phase and in the right hemisphere within the lutein phase. The viewing of emotionally negative pictures during the follicular phase led to a rise in the power of theta oscillations in the left frontal region and also to depression of the alpha activity in central/parietal parts of the left hemisphere, which can result from aggravation of anxiety and verbally shaped disturbing ideas upon the action of such stimuli. Presentation of erotically colored visual stimuli caused the most intense changes in the EEG, which depended on the phases of the ovulatory cycle, during post-stimulation time interval but not during the viewing of pictures itself. 相似文献
10.
Testis of Hemidactylus flaviviridis, commonly known as Indian wall lizard, displays a lack of cellular and metabolic activity in regressed phase of testis during non-breeding season of the year. Retracted Sertoli cells (Sc), fibroid myoid cells and pre-meiotic resting spermatogonia are observed in such testis. This situation is akin to certain forms of infertility in men where hormone supplementation fails to generate sperm despite the presence of Sc and germ cells (Gc) in testis. In testis of lizard, spermatogenesis is reinitiated upon increased level of hormones during appropriate season (phase of recrudescence). Study of genes associated with generation of sperm, from regressed adult testis in lizard, may provide valuable information for understanding certain forms of male idiopathic infertility. Subtractive hybridization using testicular RNA obtained from the regressed and active phases of lizard reproductive cycle led to identify eight partial mRNA sequences that showed sequence homology with mice genes. We further evaluated the gene expression prolife by real-time PCR in three different reproductive phases of H. flaviviridis: regressed (pre-meiotic), recrudescent (meiotic) and active (post meiotic), for comparison with the corresponding testicular phases found in testis of 5 days (pre-meiotic), 20 days (meiotic) and 60 days (post-meiotic) old mouse. This is the first report where genes associated with progression of spermatogenesis during active phase, which follows a regressed state of adult testis, were identified in lizard and found to be conserved in mouse. Six important genes, Hk1, Nme5, Akap4, Arih1, Rassf7 and Tubb4b were found to be strictly associated with active spermatogenesis in both mouse and lizard. Factors interfering with the expression of any of these genes may potentially abrogate the process of spermatogenesis leading to infertility. Such information may shed light on unknown causes of idiopathic male infertility. 相似文献
11.
12.
C. Salaun A. I. MacDonald O. Larralde L. Howard K. Lochtie H. M. Burgess M. Brook P. Malik N. K. Gray S. V. Graham 《Journal of virology》2010,84(17):8539-8548
Infection of cells by herpes simplex virus type 1 (HSV-1) triggers host cell shutoff whereby mRNAs are degraded and cellular protein synthesis is diminished. However, virus protein translation continues because the translational apparatus in HSV-infected cells is maintained in an active state. Surprisingly, poly(A)-binding protein 1 (PABP1), a predominantly cytoplasmic protein that is required for efficient translation initiation, is partially relocated to the nucleus during HSV-1 infection. This relocalization occurred in a time-dependent manner with respect to virus infection. Since HSV-1 infection causes cell stress, we examined other cell stress inducers and found that oxidative stress similarly relocated PABP1. An examination of stress-induced kinases revealed similarities in HSV-1 infection and oxidative stress activation of JNK and p38 mitogen-activated protein (MAP) kinases. Importantly, PABP relocalization in infection was found to be independent of the viral protein ICP27. The depletion of PABP1 by small interfering RNA (siRNA) knockdown had no significant effect on viral replication or the expression of selected virus late proteins, suggesting that reduced levels of cytoplasmic PABP1 are tolerated during infection.The lytic replication cycle of herpes simplex virus type 1 (HSV-1) can be divided into three phases, immediate-early (IE), early (E), and late (L), that occur in a coordinated sequential gene expression program. IE proteins can regulate E and L gene expression, which produces proteins involved in DNA replication, capsid production, and virion assembly. HSV infection results in host cell shutoff to facilitate the efficient production of viral proteins. First, mRNA is degraded by the virion-associated vhs protein, and then ICP27, a multifunctional regulator of gene expression, inhibits pre-mRNA splicing. As most viral mRNAs are intronless, this abrogates the production of stable cellular mRNAs that can be exported to the cytoplasm and compete for translation with viral mRNAs (44).HSV mRNAs are capped and polyadenylated and so are translated via a normal cap-dependent mechanism. Translation initiation, during which translationally active ribosomes are assembled, is a tightly regulated process (21). Eukaryotic initiation factor 4F (eIF4F) (composed of eIF4E, eIF4G, and eIF4A) that binds the cap at the 5′ end of the mRNA promotes the recruitment of the 40S ribosomal subunit and associated factors, including eIF2-GTP initiator tRNA. The recognition of the start codon then promotes large ribosomal subunit joining. Poly(A)-binding protein 1 (PABP1), which binds and multimerizes on mRNA poly(A) tails, enhances translation initiation through interactions with the eIF4G component of the eIF4F cap-binding complex (20, 29, 32, 51) to circularize the mRNA in a “closed-loop” conformation (24). Key protein-RNA and protein-protein interactions in the translation initiation complex are strengthened by this PABP1-mediated circularization (12).HSV-1 maintains active viral translation in the face of host translational shutoff. Infection activates protein kinase R (PKR), which phosphorylates eIF2α, resulting in translation inhibition. However, HSV-1 ICP34.5 redirects protein phosphatase 1α to reverse eIF2α phosphorylation, abrogating the block to translation (17, 38). In addition, the HSV-1 US11 protein inhibits PKR and may also block PKR-mediated eIF2α phosphorylation (40, 42). HSV-1 infection also enhances eIF4F assembly in quiescent cells by the phosphorylation and proteasome-mediated degradation of the eIF4E-binding protein (4E-BP), which, when hypophosphorylated, can negatively regulate eIF4F complex formation (54). However, ICP6 may also contribute to eIF4F assembly by binding to eIF4G (55). Finally, ICP6 is required for Mnk-1 phosphorylation of eIF4E, but the mechanisms behind this remain unclear (54). ICP27 has also been implicated in translation regulation during HSV infection (6, 8, 10, 30) and may also activate p38 mitogen-activated protein (MAP) kinase that can phosphorylate eIF4E (16, 59).PABP1 appears to be a common cellular target of RNA and DNA viruses. PABP1 can undergo proteolysis, intracellular relocalization, or modification of its interaction with other translation factors in response to infection. For example, poliovirus induces host cell shutoff by cleaving PABP1, thus disrupting certain PABP1-containing complexes (28, 29). The rotavirus NSP3 protein can displace PABP1 from translation initiation complexes (41). However, NSP3 also interacts with a cellular protein, RoXaN, which is required to relocate PABP1 to the nucleus (13). Similarly, the Kaposi''s sarcoma herpesvirus (KSHV) SOX protein plays a role in relocating PABP1, its cofactor in cellular mRNA decay, to the nucleus (33). Although steady-state levels of PABP1 are highest in the cytoplasm of normal cells, where it has cytoplasmic functions, it is a nucleocytoplasmic shuttling protein (1). However, it is unclear how PABP1 enters or exits the nucleus, as it contains neither a canonical nuclear export nor an import signal.Here we describe the loss of PABP1 from cap-binding complexes and the partial relocation of PABP1 to the nucleus in HSV-1-infected cells in a time-dependent manner. Relocation is specific for PABP1, as other translation factors remained in the cytoplasm. Cells undergo stress during HSV-1 infection, and analysis of a variety of cell stresses revealed that PABP relocalization was also observed upon oxidative stress. Paxillin, a potential PABP1 nuclear chaperone, was phosphorylated, and the paxillin-PABP1 interaction was reduced during virus infection. However, the interaction was weak and cell type dependent, indicating that other effectors of PABP1 relocation in the infected cell must exist. Recently, the HSV-1 ICP27 protein was suggested to alter the PABP1 cellular location (6). However, infections with ICP27-null mutant viruses clearly demonstrated that ICP27 is not required for PABP1 nuclear relocation in the context of infection. Although HSV-1 mRNAs are translated by a normal cap-dependent mechanism known to be enhanced by PABP1, small interfering RNA (siRNA) knockdown of PABP1 indicated that at late times of infection, the translation of certain virus late proteins tolerates very low levels of PABP1. 相似文献
13.
Gabor Erdoes Christoph Huber Reto Basciani Stefan Stortecky Stephan Windecker Peter Wenaweser Thierry Carrel Balthasar Eberle 《PloS one》2014,9(10)
Objectives
The aim of this study was to quantify potential differences in count, frequency and pattern of high-intensity transient signals (HITS) during transapical transcatheter aortic valve implantation (TA-TAVI), by comparing the Symetis Acurate TA (SA) with the balloon-expandable Edwards Sapien XT (ES) system.Background
Recently, the Symetis Acurate TA revalving system has been introduced for TA-TAVI. The Symetis Acurate TA aortic bioprosthesis is self-expanding and is deployed by a specific two-step implantation technique. Whether this novel method increases the load of intraprocedural emboli, detected by transcranial Doppler ultrasound (TCD) as HITS, or not is not clear.Methods
Twenty-two patients (n = 11 in each study arm, median logistic EuroScore 20%, median STS score 7%) displayed continuous TCD signals of good quality throughout the entire TA-TAVI procedure and were included in the final analysis. Data are presented as median with interquartile ranges.Results
No significant differences were detected in total procedural or interval-related HITS load (SA: 303 [200; 594], ES: 499 [285; 941]; p = 0.16). With both devices, HITS peaked during prosthesis deployment (PD), whereas significantly fewer HITS occurred during instrumentation (SA: p = 0.002; ES: <0.001) or post-implantation PI (SA: p = 0.007; ES: <0.001). PD-associated HITS amounted to almost half of the total HITS load. One patient suffered new disabling stroke at 30 days. Thirty-day mortality amounted to 13.6% (3 of 22 patients).Conclusions
Simplified transapical delivery using the self-expanding SA device does not increase HITS, despite of a two-step deployment technique with more interactions with the native aortic valve, when compared to the balloon-expandable ES valve. The similarity in HITS count, frequency and pattern with the two systems suggests a common mechanism for the release of cerebral microemboli. 相似文献14.
Background
Within the integrated community case management of childhood illnesses (iCCM) programme, the traditional health promotion and prevention role of community health workers (CHWs) has been expanded to treatment. Understanding both the impact and the implementation experience of this expanded role are important. In evaluating UNICEF’s implementation of iCCM, this qualitative case study explores the implementation experience in Ghana.Methods and Findings
Data were collected through a rapid appraisal using focus groups and individual interviews during a field visit in May 2013 to Accra and the Northern Region of Ghana. We sought to understand the experience of iCCM from the perspective of locally based UNICEF staff, their partners, researchers, Ghana health services management staff, CHWs and their supervisors, nurses in health facilities and mothers receiving the service. Our analysis of the findings showed that there is an appreciation both by mothers and by facility level staff for the contribution of CHWs. Appreciation was expressed for the localisation of the treatment of childhood illness, thus saving mothers from the effort and expense of having to seek treatment outside of the village. Despite an overall expression of value for the expanded role of CHWs, we also found that there were problems in supporting and sustaining their efforts. The data showed concern around CHWs being unpaid, poorly supervised, regularly out of stock, lacking in essential equipment and remaining outside the formal health system.Conclusions
Expanding the roles of CHWs is important and can be valuable, but contextual and health system factors threaten the sustainability of iCCM in Ghana. In this and other implementation sites, policymakers and key donors need to take into account historical lessons from the CHW literature, while exploring innovative and sustainable mechanisms to secure the programme as part of a government owned and government led strategy. 相似文献15.
Rooting depth and root and shoot biomass were measured for seedlings of 20 species in both watered and unwatered sand columns. The species were from habitats of widely varying moisture status, ranging from marsh to desert. Moisture status of the species' habitats was quantified as Ellenberg moisture number. Seedlings were allowed to grow in moist sand for 21 days and were then exposed to the treatments (watered and unwatered) for a further 21 days. Rooting depth of control plants was not correlated with Ellenberg number. Riit depth of plants from dry habitats tended to increase in drying sand, while roots of plants from wet habitats decreased in depth. Plasticity of rooting depth (depth in unwatered/depth in watered sand) was significantly correlated with Ellenberg number (r2=0.56). Plasticity of shoot/root ratio was also correlated with Ellenberg number, but the relationship was weaker than for rooting depth plasticity. Species that showed the greatest pasticity in rooting depth also showed the greatest ability to sustain shoot growth in unwatered sand. There was some evidence that growth of plants from very dry habitats was reduced in the watered treatment. Results of this study suggest that a major, although not the only, adaptation of plants of dry habitats is the ability of their seedlings to exploit deeply buried water resources. 相似文献
16.
Cross-Resistance to Herbicides in Annual Ryegrass (Lolium rigidum): I. Properties of the Herbicide Target Enzymes Acetyl-Coenzyme A Carboxylase and Acetolactate Synthase 总被引:1,自引:5,他引:1 下载免费PDF全文
Lolium rigidum biotype SR4/84 is resistant to the herbicides diclofop-methyl and chlorsulfuron when grown in the field, in pots, and in hydroponics. Similar extractable activities and affinities for acetyl-coenzyme A of carboxylase (ACCase), an enzyme inhibited by diclofop-methyl, were found for susceptible and resistant L. rigidum. ACCase activity from both biotypes was inhibited by diclofop-methyl, diclofop acid, haloxyfop acid, fluazifop acid, sethoxydim, and tralkoxydim but not by chlorsulfuron or trifluralin. Exposure of plants to diclofop-methyl did not induce any changes in either the extractable activities or the herbicide inhibition kinetics of ACCase. It is concluded that, in contrast to diclofop resistance in L. multiflorum and diclofop tolerance in many dicots, the basis of resistance to diclofop-methyl and to other aryloxyphenoxypropionate and cyclohexanedione herbicides in L. rigidum is not due to the altered inhibition characteristics or expression of the enzyme ACCase. The extractable activities and substrate affinity of acetolactate synthase (ALS), an enzyme inhibited by chlorsulfuron, from susceptible and resistant biotypes of L. rigidum were similar. ALS from susceptible and resistant plants was equally inhibited by chlorsulfuron. Prior exposure of plants to 100 millimolar chlorsulfuron did not affect the inhibition kinetics. It is concluded that resistance to chlorsulfuron is not caused by alterations in either the expression or inhibition characteristics of ALS. 相似文献
17.
Background The analysis of a wastewater treatment technology, under a expanded boundaries system which includes both the technology
and the inputs required for its operation, quantifies the overall environmental impact that may result from the treatment
of a wastewater stream. This is particularly useful for environmental policy makers being that a expanded boundaries system
tends to provide a holistic view. The former view can be highly enriched with the use of process engineering tools, such as
mathematical process modelling, process design, performance assessment and cost optimised models.
Main Features The traditional approach used to assess waste treatment technologies is contrasted with a life cycle analysis (LCA) approach.
The optimal design of a granular activated carbon adsorption (GAC) process is used as a model system to demonstrate the advantages
of LCA approaches over traditional approaches. Further sections of the paper describe a mathematical framework for the assessment
of technologies, design considerations applied in the cost optimised carbon adsorption model, the use of LCA techniques to
perform an inventory of all emissions associated to the process system and, some of its environmental impacts.
Results Economic and environmental considerations regarding the optimum process design are introduced as a basis for decision towards
the selection and operating conditions of wastewater treatment technologies. Moreover, the use of LCA has revealed that the
environmental burden associated with the wastewater treatment may produce a higher environmental impact than one that can
be caused by untreated discharges.
Conclusion The paper highlights the string advantages that environmental policy makers may have by combining LCA and process engineering
tools. Furthermore, this approach can be incorporated into other existing treatment processes or for process designers. 相似文献
18.
A Study of Phospholipids and Galactolipids in Pollen of Two Lines of Brassica napus L. (Rapeseed) with Different Ratios of Linoleic to Linolenic Acid 总被引:1,自引:0,他引:1 下载免费PDF全文
The phospholipids and galactolipids of the pollen-coat and internal domains of two lines of Brassica napus, Wesroona and IXLIN, with different linoleic/linolenic acid ratios (18:2/18:3) have been characterized by normal phase silica high performance liquid chromatography and gas liquid chromatography. The polar lipids of the pollen-coat are similar to leaf lipids in the high proportion of galactolipids (almost 50%) and the fatty acids; 18:3, palmitic (16:0) and hexadecatrienoic (16:3). In contrast, the pollen internal domain, although rich in 18:3, 18:2 and 16:0, is composed primarily of phosphatidyl-choline, -ethanolamine, and -inositol whose 18:2/18:3 ratio is correlated with that of the seed generation. The difference between the two divergent 18:2/18:3 ratio lines is most evident in the internal domain phospholipids. The 18:2/18:3 ratio of the galactolipids of both pollen domains is not significantly effected by the line genotype. The results are interpreted in terms of the previously described `prokaryotic' and `eukaryotic' plant desaturation pathways (PG Roughan, CR Slack [1982] Annu Rev Plant Physiol 33: 97-132). We propose that the eukaryotic pathway is the major desaturation pathway providing polyunsaturated fatty acids to the haploid-specified internal domain in which the IXLIN genotype modifies the activity of the sn-2 linoleoyl phosphatidylcholine desaturase/s of the endoplasmic reticulum. In the diploid-specified pollen-coat, our evidence suggests that a combination of the prokaryotic and eukaryotic pathways contribute polyunsaturated fatty acids. 相似文献
19.
The digestive glands of Pinguicula vulgaris become fully maturewhilst still enclosed in the bud. All the gland cells remainintact on the fully expanded unstimulated leaves. As the secretoryhead cells mature, a special layer forms between the plasmalemmaand the cell wall. This layer is shown to be different fromthe typical labyrinthine wall of transfer cells and serves forthe storage of digestive enzymes. Ultrastructural analysis,including morphometry, indicates that the digestive enzymesare synthesized on the RER of the head cells and transferredinto the cell wall, particularly into the slime layer, and vacuoles.This transfer is achieved firstly through continuity of theendoplasmic reticulum with vacuoles (static) and the periplasmicspace (dynamic) and, secondly, into the latter through exocytosisof coated Golgi vesicles and of some vacuoles filled with enzymes. Pinguicula vulgaris L., carnivorous plant, digestive glands, ultrastructure, protein synthesis secretion 相似文献
20.
Kevin P. Brady Holly Dushkin Dorothee Frnzler Tatsuya Koike Fiona Magner Helen Her Steven Gullans Gino V. Segre Richard M. Green David R. Beier 《Genomics》1999,56(3):254
The phenotype of mice homozygous for the osteosclerosis (oc) mutation includes osteopetrosis, and a variety of studies demonstrate that osteoclasts in these mice are present but nonfunctional. We have identified a novel gene that has homology to a family of 12-transmembrane domain proteins with transport functions and maps to proximal mouse chromosome 19, in a region to which theocmutation has been previously assigned. The putative transporter is abundant in normal kidney, but its expression is markedly reduced in kidneys fromoc/ocmice when tested using Northern and Western analyses. Southern analysis of this gene, which we callRoct(reduced inoctransporter), demonstrates that it is intact and unrearranged inoc/ocmice.In situstudies show thatRoctis expressed in developing bone. We propose that the absence ofRoctexpression results in an osteopetrosis phenotype in mice. 相似文献