植物挥发性信号物质介导抗性的生态功能

植物产生的挥发性化合物能够作为媒介参与植物与周围环境之间的信息交流及相互作用。植物挥发性物质在吸引传粉者、促进种子传播、抑制其它植物种子萌发等方面具有重要的作用。近年来,关于植物挥发性物质在生态系统中的信号作用研究已经成为国内外的研究热点,受到广泛关注。总结了植物挥发性物质作为信号物质在提高植物抗性方面的国内外研究成果,阐述了植物挥发性物质不仅能够直接提高植物的抗性,而且可以作为信号物质在同株、同种异株和不同种植物之间进行传递,进而间接提高目标植物的抗性。最后,还对植物挥发性物质的研究方法和潜在的生态功能进行了探讨。     

An evolutionary expressed sequence tag analysis of Drosophila spermatheca genes

This study investigates genes enriched for expression in the spermatheca, the long-term sperm storage organ (SSO) of female Drosophila. SSO genes are likely to play an important role in processes of sexual selection such as sperm competition and cryptic female choice. Although there is keen interest in the mechanisms of sexual selection at the molecular level, very little is known about the female genes that are involved. In the present study, a high proportion of genes enriched for expression in the spermatheca are evolving rapidly. Most of the rapidly evolving genes are proteases and genes of unknown function that could play a specialized role in the spermatheca. A high percentage of the rapidly evolving genes have secretion signals and thus could encode proteins that directly interact with ejaculate proteins and coevolve with them. In addition to identifying rapidly evolving genes, the present study documents categories of genes that could play a role in spermatheca function such as storing, maintaining, and utilizing sperm. In general, candidate genes discovered in this study could play a key role in sperm competition, cryptic female choice of sperm, and sexually antagonistic coevolution, and ultimately speciation.     

The role of metals in neurodegenerative diseases.

There is increasing evidence in a number of neurodegenerative diseases that transition metal-mediated abnormalities play a crucial role in disease pathogenesis. In this treatise, we review the role of metal homeostasis as it pertains to alterations in brain function in neurodegenerative diseases. In fact, while there is documented evidence for alterations in transition metal homeostasis, redox-activity and localization, it is also important to realize that alterations in specific copper- and iron-containing metalloenzymes also appear to play a crucial role in the neurodegenerative process.     

Mitochondrial carriers and pores: Key regulators of the mitochondrial apoptotic program?

Mitochondria play a pivotal role in the process of apoptosis. Alterations in mitochondrial structure and function during apoptosis are regulated by proteins of the BCL-2 family, however their exact mechanism of action is largely unknown. Mitochondrial carriers and pores play an essential role in maintaining the normal function of mitochondria, and BCL-2 family members were shown to interact with several mitochondrial carriers/pores and to affect their function. This review focuses on the involvement of several of these mitochondrial carriers/pores in the regulation of the mitochondrial death pathway.     

Gap junctions in skeletal development and function

Gap junctions play a critical role in the coordinated function and activity of nearly all of the skeletal cells. This is not surprising, given the elaborate orchestration of skeletal patterning, bone modeling and subsequent remodeling, as well as the mechanical stresses, strains and adaptive responses that the skeleton must accommodate. Much remains to be learned regarding the role of gap junctions and hemichannels in these processes. A common theme is that without connexins none of the cells of bone function properly. Thus, connexins play an important role in skeletal form and function.     

Bruton's Tyrosine Kinase is involved in innate and adaptive immunity

Btk is a cytoplasmic tyrosine kinase, which is mainly involved in B cell receptor signalling. Gene targeting experiments revealed that Btk is important for B cell development and function. However, Btk is not only expressed in B cells, but also in most other haematopoietic lineages except for T cells and plasma cells. Recently we found that Btk is involved in Toll-like receptor signalling. Toll-like receptors play an important role in innate immunity. They are highly expressed on mast cells, macrophages and dendritic cells, which are essential for the recognition and consequently for the elimination of microbial pathogens. Therefore Btk might play an important role for the function of immunocompetent cells of innate as well as adaptive immunity.     

Mast cells in tumor growth: Angiogenesis,tissue remodelling and immune-modulation

There is a growing acceptance that tumor-infiltrating myeloid cells play an active role in tumor growth and mast cells are one of the earliest cell types to infiltrate developing tumors. Mast cells accumulate at the boundary between healthy tissues and malignancies and are often found in close association with blood vessels within the tumor microenvironment. They express many pro-angiogenic compounds, and may play an early role in angiogenesis within developing tumors. Mast cells also remodel extracellular matrix during wound healing, and this function is subverted in tumor growth, promoting tumor spread and metastasis. In addition, mast cells modulate immune responses by dampening immune rejection or directing immune cell recruitment, depending on local stimuli. In this review, we focus on key roles for mast cells in angiogenesis, tissue remodelling and immune modulation and highlight recent findings on the integral role that mast cells play in tumor growth. New findings suggest that mast cells may serve as a novel therapeutic target for cancer treatment and that inhibiting mast cell function may lead to tumor regression.     

The guanine nucleotide-binding regulatory proteins (G proteins) in myocardium with ischemia

Guanine nucleotide-binding regulatory proteins (G proteins) play a major role in the regulation of a number of physiological processes, such as stimulation or Inhibition of adenylate cyclase activity or gaiting of ionic channels. Myocardial ischemia could induce the changes in receptor-G protein signal transduction system in the heart. Therefore, this article will focus on the role and alterations of G proteins (especially, Gs and Gi) in myocardial ischemia. The Gi protein rapidly loses functional activity during very early myocardial ischemia. In contrast to Gi protein, the function of Gs protein during this phase has not been evaluated. Moreover, the changes in Gs protein after 30 min of ischemia are contradictory. However, the sensitization of the adenylate cyclase activity in the very early phase of acute ischemia is gradually replaced by a decrease in adenylate cyclase activity with prolonged ischemia. The decrease in the function and amount of Gs protein may be one of the factors that induce these changes. The function of Gs protein was also decreased in the canine hearts with ischemia and reperfusion. In contrast to ischemia and reperfusion, there are no significant alterations in G proteins and modulation of adenylate cyclase in the stunned myocardium. It has become increasingly evident that Gi protein may play an important role in the cardioprotective effects of preconditioning. When -adrenoceptor densities are reduced in chronic myocardial ischemia, decreased in the amount and function of Gi protein and increased amount of Gs protein may play the role in preservation of the adenylate cyclase activity. These alterations in G proteins may play the important role in the myocardial function during myocardial ischemia.     

A review of FGF18: Its expression, signaling pathways and possible functions during embryogenesis and post-natal development

FGF18 is a novel growth factor first reported in 1998. Current evidence suggests that FGF18 may play a prominent role in chondrogenesis and osteogenesis during skeletal development and growth. However, its function extends to many other biological processes. Although there remains much to be discovered and investigated on the functions and mechanisms of FGF18, it may play a role as a useful therapeutic target for various applications. The following review summarizes the current knowledge on FGF18 with special emphasis on its skeletal functions and highlights its potential areas for future research.     

Hormonal control of macrophage function and glutamine metabolism

Murine macrophages have been reported to utilize glutamine at high rates. However, the role of glutamine in macrophage function is still unknown. In the present study, the maximum glutaminase activity of macrophages was investigated under several endocrine dysfunctions that are known to cause alterations in macrophage function. The results obtained suggest that glutamine might play an important role in the onset of phagocytosis in inflammatory macrophages. Moreover, the studies show that insulin, glucocorticoids, and thyroid hormones may be responsible for the regulation of glutamine metabolism and, consequently, of macrophage function.     

The significance of peroxisomes in secondary metabolite biosynthesis in filamentous fungi

Peroxisomes are ubiquitous organelles characterized by a protein-rich matrix surrounded by a single membrane. In filamentous fungi, peroxisomes are crucial for the primary metabolism of several unusual carbon sources used for growth (e.g. fatty acids), but increasing evidence is presented that emphasize the crucial role of these organelles in the formation of a variety of secondary metabolites. In filamentous fungi, peroxisomes also play a role in development and differentiation whereas specialized peroxisomes, the Woronin bodies, play a structural role in plugging septal pores. The biogenesis of peroxisomes in filamentous fungi involves the function of conserved PEX genes, as well as genes that are unique for these organisms. Peroxisomes are also subject to autophagic degradation, a process that involves ATG genes. The interplay between organelle biogenesis and degradation may serve a quality control function, thereby allowing a continuous rejuvenation of the organelle population in the cells.     

Heparan sulfate proteoglycans in invasion and metastasis

Because heparan sulfate proteoglycans mediate cell adhesion and control the activities of numerous growth and motility factors, they play a critical role in regulating the metastatic behavior of tumor cells. Due to their utilitarian nature, heparan sulfate proteoglycans may at times act as inhibitors of cell invasion and at other times as promoters of cell invasion, with their function being determined by their location (cell surface or extracellular matrix), the heparin-binding molecules they associate with, the presence of modifying enzymes (proteases, heparanases) and the precise structural characteristics of the proteoglycan. Also, the tissue type and pathophysiological state of the tumor influence proteogylcan function. This review summarizes our current knowledge of the role heparan sulfate proteoglycans play in regulating tumor cell metastasis, proposes mechanisms of how these molecules function and examines the potential for discovery of new therapeutic approaches designed to block metastatic cancer.     

Role of toll-like receptors in tissue repair and tumorigenesis

Toll-like receptors (TLRs) play a critical role in host defense from microbial infection. TLRs recognize conserved molecular structures produced by microorganisms and induce activation of innate and adaptive immune responses. The inflammatory responses induced by TLRs play an important role TLRs not only in host defense from infection, but also in tissue repair and regeneration. This latter function of TLRs can also contribute to tumorigenesis. Here we review recent progress in understanding the role of TLRs in cancer development.     

TIR-containing adaptors in Toll-like receptor signalling

While the Toll-like receptors (TLRs) are responsible for the recognition and response to pathogen ligands, increasing evidence suggests that the family of five cytosolic Toll/IL-1 receptor (TIR) adaptor proteins also play a crucial role in the specificity of the response. Genetic studies in mice, and increasingly in human polymorphic populations, have given us a greater understanding the role these adaptors play in orchestrating and coordinating the multifaceted immune response to multiple exogenous threats. Importantly, with growing evidence of the critical role TLRs play in responses to host danger signals and autoimmune disease, a more comprehensive understanding and appreciation of the role these adaptors play in disease progression may provide future targets for therapeutic intervention in human disease. Importantly, growing evidence supports the concept of pathway specific and inflammatory control by a better understanding of how these adaptors interact with other signalling mediators, where they localise within the cell and the inflammatory programs they initiate as a way of manipulating immune responses. This review deals with our current understanding of these TIR-containing adaptor proteins and how mutagenesis of specific residues and domains has increased our knowledge of their function in TLR immune responses.     

Contralateral Masking in Bilateral Cochlear Implant Patients: A Model of Medial Olivocochlear Function Loss

Contralateral masking is the phenomenon where a masker presented to one ear affects the ability to detect a signal in the opposite ear. For normal hearing listeners, contralateral masking results in masking patterns that are both sharper and dramatically smaller in magnitude than ipsilateral masking. The goal of this study was to investigate whether medial olivocochlear (MOC) efferents are needed for the sharpness and relatively small magnitude of the contralateral masking function. To do this, bilateral cochlear implant patients were tested because, by directly stimulating the auditory nerve, cochlear implants circumvent the effects of the MOC efferents. The results indicated that, as with normal hearing listeners, the contralateral masking function was sharper than the ipsilateral masking function. However, although there was a reduction in the magnitude of the contralateral masking function compared to the ipsilateral masking function, it was relatively modest. This is in sharp contrast to the results of normal hearing listeners where the magnitude of the contralateral masking function is greatly reduced. These results suggest that MOC function may not play a large role in the sharpness of the contralateral masking function but may play a considerable role in the magnitude of the contralateral masking function.     

The role of peroxidases in pistil-pollen interactions

Summary The majority of pistil peroxidases are involved in processes related to growth, development and senescence. Only the tissue specific peroxidases in the transmitting tissue of the style may play a direct role in the regulation of pollen tube growth. The pollen peroxidases may function mainly in growth regulation and tube wall formation and play a role in the interaction between pollen and pistil by metabolizing the phenolic compounds in the pistil.     

Inflammatory signaling and cellular senescence

Inflammation acts as a double-edged sword in the pathogenesis of cancer. Inflammatory responses play a key role in eliminating potentially cancerous cells; however, an inflammatory microenvironment also promotes the development of cancer. Proinflammatory cytokines, the key mediators of inflammation, also play a dual role in oncogenesis. While they can promote neoplastic progression, recent studies have revealed an unexpected function of the inflammatory pathways in inhibiting cancer development. These studies demonstrate that cells undergoing senescence, a cellular program serving as a barrier to cancer development, produce increased amount of inflammatory cytokines. These inflammatory cytokines play an essential role in the initiation and maintenance of cellular senescence, and are responsible for triggering an innate immune response that clears the senescent tumor cells in vivo. The purpose of the present review is to discuss the dual roles of the inflammatory cytokines produced by senescent cells in the pathogenesis of cancer, and the signaling pathway mediating their role in cellular senescence.     

A critical analysis of Australian clinical ethics committees and the functions they serve

The predominant function of Australian clinical ethics committees (CECs) is policy formation. Some committees have an educational role. Few committees play any direct role in advising on ethics in the management of individual patients and this occurs only in exceptional circumstances. There is a tendency to exaggerate both the number and function of committees. It is suggested that studies of ethics committees, based on questionnaire surveys, should be interpreted cautiously. An examination of ethical issues indicates that there is a role for a critical analysis of power relations in Australian hospitals that is not fulfilled by CECs.     

Small RNAs in early mammalian development: from gametes to gastrulation

Small non-coding RNAs, including microRNAs (miRNAs), endogenous small interfering RNAs (endo-siRNAs) and Piwi-interacting RNAs (piRNAs), play essential roles in mammalian development. The function and timing of expression of these three classes of small RNAs differ greatly. piRNAs are expressed and play a crucial role during male gametogenesis, whereas endo-siRNAs are essential for oocyte meiosis. By contrast, miRNAs are ubiquitously expressed in somatic tissues and function throughout post-implantation development. Surprisingly, however, miRNAs are non-essential during pre-implantation embryonic development and their function is suppressed during oocyte meiosis. Here, we review the roles of small non-coding RNAs during the early stages of mammalian development, from gamete maturation through to gastrulation.     

The intramolecular chaperone-mediated protein folding

Some proteins have evolved to contain a specific sequence as an intramolecular chaperone, which is essential for protein folding but not required for protein function, as it is removed after the protein is folded by autoprocessing or by an exogenous protease. To date, a large number of sequences encoded as N-terminal or C-terminal extensions have been identified to function as intramolecular chaperones. An increasing amount of evidence has revealed that these intramolecular chaperones play an important role in protein folding both in vivo and in vitro. Here, we summarize recent studies on intramolecular chaperone-assisted protein folding and discuss the mechanisms as to how intramolecular chaperones play roles in protein folding.