The yeast Pho80–Pho85 cyclin–CDK complex has multiple substrates

The Pho85–Pho80 cyclin–CDK (cyclin-dependent protein kinase) complex of Saccharomyces cerevisiae functions as a key regulator of the phosphate-repressible acid phosphatase system. We have further characterized the Pho85–Pho80 kinase complex and identified the Pho80 cyclin subunit and the Pho81 CDK inhibitor as substrates of the Pho85 protein kinase. The phosphorylation sites within Pho80 have been identified at Ser²³⁴ and Ser²⁶⁷. Of the two sites, phosphorylation of Ser²³⁴ is required for Pho80 function, to form an active kinase complex and repress acid phosphatase expression. Evidence suggests that the activity of Pho81 is regulated by a post-translational modification and therefore that Pho85-mediated phosphorylation of Pho81 may alter its ability to function as a CDK inhibitor. Thus, the control of acid phosphatase expression involves the phosphorylation of several of the regulatory components of the system.     

CDK-dependent complex formation between replication proteins Dpb11, Sld2, Pol ?, and GINS in budding yeast

Eukaryotic chromosomal DNA replication requires cyclin-dependent kinase (CDK) activity. CDK phosphorylates two yeast replication proteins, Sld3 and Sld2, both of which bind to Dpb11 when phosphorylated. These phosphorylation-dependent interactions are essential and are the minimal requirements for CDK-dependent activation of DNA replication. However, how these interactions activate DNA replication has not been elucidated. Here, we show that CDK promotes the formation of a newly identified fragile complex, the preloading complex (pre-LC) containing DNA polymerase ɛ (Pol ɛ), GINS, Sld2, and Dpb11. Formation of the pre-LC requires phosphorylation of Sld2 by CDK, but is independent of DNA replication, protein association with replication origins, and Dbf4-dependent Cdc7 kinase, which is also essential for the activation of DNA replication. We also demonstrate that Pol ɛ, GINS, Dpb11, and CDK-phosphorylated Sld2 form a complex in vitro. The genetic interactions between Pol ɛ, GINS, Sld2, and Dpb11 suggest further that they form an essential complex in cells. We propose that CDK regulates the initiation of DNA replication in budding yeast through formation of the pre-LC.     

Calcitonin and its antinociceptive activity: Animal and human investigations 1975–1992

Calcitonin (CT) is a polypeptide hormone produced in the thyroid gland that regulates, blood calcium levels and bone calcium metabolism.The unexpected finding of binding sites for calcitonin in several areas of the brain oriented attention to activities of CT in the central nervous system and also to its antinociceptive action.The first report of this last effect was in 1975, and the many different experimental and clinical data on this topic reported since then are reviewed here.The heterogenous findings have been organized according to the logical classification of animal and human studies. For each of these headings, subheadings such as acute and chronic pain, different kinds of administration and different procedures used to record the results, are considered.The several proposed mechanisms of action, involving serotoninergic, catecholaminergic, Ca²⁺ fluxes, protein phosphorylation, -endorphin production, cyclooxygenase inhibition and histamine interference are also reviewed.Calcitonin, neurotensin, substance P, VIP and, recently, CGRP are some of the non-opioid peptides that have been reported to interfere with pain and that open up a new, alternative way of investigating antinociceptive drugs different than opioid or opioid-like agents.An examination of the state-of-investigation of calcitonin's antinociceptive activity in the last 17 years shows that many experimental studies indicate the existence of this effect, including studies in humans, and this opens up perspectives for therapy with a new class of antinociceptive agents.     

Epistatic interactions between Fc (GM) and FcγR genes and the host control of human immunodeficiency virus replication

Host genetic factors are thought to contribute to the interindividual differences in the control of human immunodeficiency virus (HIV) replication. The aim of the present investigation was to determine whether genes encoding GM and KM allotypes-genetic markers of immunoglobulin γ and κ chains, respectively-and those encoding Fcγ receptor (FcγR) IIa and IIIa are associated with the host control of HIV replication. A case-control design was employed among HIV-infected subjects, with a group that spontaneously controlled HIV replication ("controllers") as cases (n = 73) and those who did not control replication as controls (n = 100). Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism, direct DNA sequencing, and TaqMan genotyping assays. In Caucasian Americans, certain combinations of FcγR and GM genotypes were differentially distributed between controllers and noncontrollers. Among the noncarriers of the FcγRIIa arginine allele, GM21 noncarriers had over 7-fold greater odds of being controllers than the carriers of this allele (odds ratio [OR] = 7.47). These GM determinants also interacted with FcγRIIIa alleles. Among the carriers of the FcγRIIIa valine allele, GM21 noncarriers had over 3-fold greater odds of being controllers than the carriers of this allele (OR = 3.26). These results demonstrate epistatic interactions of genes on chromosomes 14 (GM) and 1 (FcγR) in influencing the control of HIV replication.     

The social stressors-counterproductive work behaviors link: are conflicts with supervisors and coworkers the same?

The differential impact of conflict with supervisors and coworkers on the target of counterproductive work behaviors (CWB) was investigated using multiple data sources. The mediating role of negative emotions was also tested using an emotion-centered model of CWB. Data were obtained from 133 dyads (incumbents plus a coworker) of full-time working participants representing a variety of occupations at the University of South Florida. Participants in the incumbent role were asked to complete a questionnaire measuring demographics, conflict, negative emotions, and CWB. The coworker was asked to respond to a shorter questionnaire measuring conflict and CWB regarding the incumbent's job. Evidence for a differential relationship between conflict sources and the target of CWB was found. The emotion-centered model of voluntary work behavior received partial support.     

The Work–Family Interface and Sleep Quality

Objective: This article investigated whether work-to-family conflict (WFC) and work-to-family enrichment (WFE) were associated with employee sleep quality. WFC and WFE reflect the potential for experiences at work to negatively and positively influence nonworking life respectively, and may have implications for sleep quality. In this article, we examined whether WFC and WFE were linked with sleep quality via hedonic balance (i.e., positive affect relative to negative affect). Participants: The sample included 3,170 employed Australian parents involved in the Household Income and Labour Dynamics in Australia (HILDA) Survey. Methods: Information on WFC, WFE, hedonic balance, sleep quality, and relevant covariates was collected through a structured interview and self-completion questionnaire. Results: WFC was associated with poorer sleep quality (β = .27, p < .001), and this relationship was stronger in males than females and in dual parent–single income families. WFC was also found to be indirectly associated with poor sleep quality via a lower hedonic balance (β = .17, 99% confidence interval [.14, .20]). WFE was not directly associated with sleep quality, but was indirectly associated with better sleep quality via a higher hedonic balance (β = –.04 [–.07, –.02]). Conclusions: These results indicate that aspects of the work–family interface are associated with employee sleep quality. Furthermore, affective experiences were found to link WFC and WFE with sleep quality. Workplace interventions that target WFC and WFE may have implications for employee sleep.     

Uptake and transfection efficiency of PEGylated cationic liposome–DNA complexes with and without RGD-tagging

Steric stabilization of cationic liposome–DNA (CL–DNA) complexes is required for in vivo applications such as gene therapy. PEGylation (PEG: poly(ethylene glycol)) of CL–DNA complexes by addition of PEG2000-lipids yields sterically stabilized nanoparticles but strongly reduces their gene delivery efficacy. PEGylation-induced weakening of the electrostatic binding of CL–DNA nanoparticles to cells (leading to reduced uptake) has been considered as a possible cause, but experimental results have been ambiguous. Using quantitative live-cell imaging in vitro, we have investigated cell attachment and uptake of PEGylated CL–DNA nanoparticles with and without a custom synthesized RGD-peptide grafted to the distal ends of PEG2000-lipids. The RGD-tagged nanoparticles exhibit strongly increased cellular attachment as well as uptake compared to nanoparticles without grafted peptide. Transfection efficiency of RGD-tagged PEGylated CL–DNA NPs increases by about an order of magnitude between NPs with low and high membrane charge density (σ_M; the average charge per unit area of the membrane; controlled by the molar ratio of cationic to neutral lipid), even though imaging data show that uptake of RGD-tagged particles is only slightly enhanced by high σ_M. This suggests that endosomal escape and, as a result, transfection efficiency of RGD-tagged NPs is facilitated by high σ_M. We present a model describing the interactions between PEGylated CL–DNA nanoparticles and the anionic cell membrane which shows how the PEG grafting density and membrane charge density affect adhesion of nanoparticles to the cell surface.     

Targeting the ecology within: The role of the gut–brain axis and human microbiota in drug addiction

Despite major advances in our understanding of the brain using traditional neuroscience, reliable and efficacious treatments for drug addiction have remained elusive. Hence, the time has come to utilize novel approaches, particularly those drawing upon contemporary advances in fields outside of established neuroscience and psychiatry. Put another way, the time has come for a paradigm shift in the addiction sciences.Apropos, a revolution in the area of human health is underway, which is occurring at the nexus between enteric microbiology and neuroscience. It has become increasingly clear that the human microbiota (the vast ecology of bacteria residing within the human organism), plays an important role in health and disease. This is not surprising, as it has been estimated that bacteria living in the human body (approximately 1 kg of mass, roughly equivalent to that of the human brain) outnumber human cells 10 to 1. While advances in the understanding of the role of microbiota in other areas of human health have yielded intriguing results (e.g., Clostridium difficile, irritable bowel syndrome, autism, etc.), to date, no systematic programs of research have examined the role of microbiota in drug addiction.The current hypothesis, therefore, is that gut dysbiosis plays a key role in addictive disorders. In the context of this hypothesis, this paper provides a rationale for future research to target the “gut–brain axis” in addiction. A brief background of the gut–brain axis is provided, along with a series of hypothesis-driven ideas outlining potential treatments for addiction via manipulations of the “ecology within.”     

The Meckel’s cartilage in human embryonic and early fetal periods

The Meckel’s cartilage itself and the mandible are derived from the first branchial arch, and their development depends upon the contribution of the cranial neural crest cells. The prenatal development of the Meckel’s cartilage, along with its relationship to the developing mandible and the related structures, were studied histologically in human embryos and fetuses. The material was obtained from a collection of the Department of Anatomy, and laboratory procedures were used to prepare sections, which were stained according to standard light-microscopy methods. The formation of the Meckel’s cartilage and its related structures was observed and documented. Some critical moments in the development of the Meckel’s cartilage are suggested. The sequential development of the Meckel’s cartilage started as early as stage 13 (32 days) with the appearance of condensation of mesenchymal cells within the mandibular prominence. During stage 17 (41 days), the primary ossification center of the mandible appeared on the inferior margin of the Meckel’s cartilage. The muscular attachments to the Meckel’s cartilage in embryos were observed at stage 18 (44 days). Their subsequent movement into the developing mandible during the 10th week seemed to diminish the role of the Meckel’s cartilage as the supportive core; simultaneously, the process of regression within the cartilage was induced. During the embryonic period, the bilateral Meckel’s cartilages were in closest contact at the posterior surface of their superior margins, preceding formation of the symphyseal cartilage at this site. The event sequence in the development of the Meckel’s cartilage is finally discussed.     

The blood–brain and the blood–cerebrospinal fluid barriers: function and dysfunction

The central nervous system (CNS) is tightly sealed from the changeable milieu of blood by the blood–brain barrier (BBB) and the blood–cerebrospinal fluid (CSF) barrier (BCSFB). While the BBB is considered to be localized at the level of the endothelial cells within CNS microvessels, the BCSFB is established by choroid plexus epithelial cells. The BBB inhibits the free paracellular diffusion of water-soluble molecules by an elaborate network of complex tight junctions (TJs) that interconnects the endothelial cells. Combined with the absence of fenestrae and an extremely low pinocytotic activity, which inhibit transcellular passage of molecules across the barrier, these morphological peculiarities establish the physical permeability barrier of the BBB. In addition, a functional BBB is manifested by a number of permanently active transport mechanisms, specifically expressed by brain capillary endothelial cells that ensure the transport of nutrients into the CNS and exclusion of blood-borne molecules that could be detrimental to the milieu required for neural transmission. Finally, while the endothelial cells constitute the physical and metabolic barrier per se, interactions with adjacent cellular and acellular layers are prerequisites for barrier function. The fully differentiated BBB consists of a complex system comprising the highly specialized endothelial cells and their underlying basement membrane in which a large number of pericytes are embedded, perivascular antigen-presenting cells, and an ensheathment of astrocytic endfeet and associated parenchymal basement membrane. Endothelial cell morphology, biochemistry, and function thus make these brain microvascular endothelial cells unique and distinguishable from all other endothelial cells in the body. Similar to the endothelial barrier, the morphological correlate of the BCSFB is found at the level of unique apical tight junctions between the choroid plexus epithelial cells inhibiting paracellular diffusion of water-soluble molecules across this barrier. Besides its barrier function, choroid plexus epithelial cells have a secretory function and produce the CSF. The barrier and secretory function of the choroid plexus epithelial cells are maintained by the expression of numerous transport systems allowing the directed transport of ions and nutrients into the CSF and the removal of toxic agents out of the CSF. In the event of CNS pathology, barrier characteristics of the blood–CNS barriers are altered, leading to edema formation and recruitment of inflammatory cells into the CNS. In this review we will describe current knowledge on the cellular and molecular basis of the functional and dysfunctional blood–CNS barriers with focus on CNS autoimmune inflammation.