The γ -Tubulin Complex Protein GCP4 Is Required for Organizing Functional Microtubule Arrays in Arabidopsis thaliana

Microtubule (MT) nucleation and organization depend on the evolutionarily conserved protein γ -tubulin, which forms a complex with GCP2-GCP6 (GCP for γ -Tubulin Complex Protein). To date, it is still unclear how GCP4-GCP6 (the non-core GCPs) may be involved in acentrosomal MT nucleation in plant cells. We found that GCP4 was associated with γ -tubulin in vivo in Arabidopsis thaliana. When GCP4 expression was repressed by an artificial microRNA, transgenic plants exhibited phenotypes of dwarfism and reduced organ size. In mitotic cells, it was observed that the γ -tubulin signal associated with the mitotic spindle, and the phragmoplast was depleted when GCP4 was downregulated. Consequently, MTs failed to converge at unified spindle poles, and the bipolar phragmoplast MT array frequently had discrete bundles with extended minus ends, resulting in failed cytokinesis as reflected by cell wall stubs in leaf epidermal cells. In addition, cortical MTs in swollen guard cells and pavement cells of the leaf epidermis became hyperparallel and bundled, which was likely caused by frequent MT nucleation with shallow angles on the wall of extant MTs. Therefore, our results support the notion that GCP4 is an indispensable component for the function of γ -tubulin in MT nucleation and organization in plant cells.     

Segmentation of center brains and optic lobes in 3D confocal images of adult fruit fly brains

Automatic alignment (registration) of 3D images of adult fruit fly brains is often influenced by the significant displacement of the relative locations of the two optic lobes (OLs) and the center brain (CB). In one of our ongoing efforts to produce a better image alignment pipeline of adult fruit fly brains, we consider separating CB and OLs and align them independently. This paper reports our automatic method to segregate CB and OLs, in particular under conditions where the signal to noise ratio (SNR) is low, the variation of the image intensity is big, and the relative displacement of OLs and CB is substantial.We design an algorithm to find a minimum-cost 3D surface in a 3D image stack to best separate an OL (of one side, either left or right) from CB. This surface is defined as an aggregation of the respective minimum-cost curves detected in each individual 2D image slice. Each curve is defined by a list of control points that best segregate OL and CB. To obtain the locations of these control points, we derive an energy function that includes an image energy term defined by local pixel intensities and two internal energy terms that constrain the curve’s smoothness and length. Gradient descent method is used to optimize this energy function. To improve both the speed and robustness of the method, for each stack, the locations of optimized control points in a slice are taken as the initialization prior for the next slice. We have tested this approach on simulated and real 3D fly brain image stacks and demonstrated that this method can reasonably segregate OLs from CBs despite the aforementioned difficulties.     

CTRP3/cartducin is induced by transforming growth factor‐β1 and promotes vascular smooth muscle cell proliferation

CTRP3 (C1q and tumour necrosis factor‐related protein 3)/cartducin, a novel serum protein, is a member of the CTRP superfamily. Although the CTRP3/cartducin gene is markedly up‐regulated in rat carotid arteries after balloon injury, little is known about its biological roles in arterial remodelling and neointima formation in injured blood vessels. We have investigated the mechanisms underlying CTRP3/cartducin up‐regulation and the in vitro effects of CTRP3/cartducin on vascular smooth muscle cells. CTRP3/cartducin expression in cultured p53LMAC01 vascular smooth muscle cells was induced by TGF‐β1 (transforming growth factor‐β1), but not by bFGF (basic fibroblast growth factor) or PDGF‐BB (platelet‐derived growth factor‐BB). Exogenous CTRP3/cartducin promoted the proliferation of p53LMAC01 cells in a dose‐dependent manner via ERK1/2 (extracellular signal‐regulated kinase 1/2)‐ and MAPK (p38 mitogen‐activated protein kinase)‐signalling pathways. In contrast, CTRP3/cartducin exhibited no effect on the migration of p53LMAC01 cells. Taken together, the results of the present study demonstrate a novel biological role of CTRP3/cartducin in promoting vascular smooth muscle cell proliferation in blood vessel walls after injury.     

Cancer Cluster Investigation in Residents Near a Municipal Landfill

While there are several studies of the health status of residents near hazardous waste landfills, relatively few have focused on the health of individuals living near municipal landfills. We assessed whether there were increased incidence rates of 18 cancer types and all cancers combined among residents near the Northampton Regional Landfill in western Massachusetts by conducting analyses for the cities of Northampton and Easthampton, as well as each census tract in these cities, between years 1982 and 2004. We also examined incidence rates within a 1-mile radius of the landfill and examined spatial patterns of all cancer cases in Northampton and Easthampton. The majority of cancer types occurred at, near, or below expected rates. No statistically significant association persisted over time. Within 1 mile of the landfill, all cancers combined occurred at rates comparable to the statewide average (SIR = 94, 95% CI: 69, 120) from 1997 to 2004, as did all individual cancer types analyzed. There were no unusual spatial patterns of cases in the area surrounding the landfill for the entire study period or four individual periods examined. The results do not support the hypothesis that residing near the investigated municipal landfill was associated with increased cancer risk.     

Multifaceted deaths orchestrated by mitochondria in neurones

Neurones undergo diverse forms of cell death depending on the nature and severity of the stress. These death outcomes are now classified into various types of programmed cell death, including apoptosis, autophagy and necrosis. Each of these pathways can run in parallel and all have mitochondria as a central feature. Recruitment of mitochondria into cell death signalling involves either (or both) induction of specific death responses through release of apoptogenic proteins into the cytosol, or perturbation in function leading to loss of mitochondrial energisation and ATP synthesis. Cross-talk between these signalling pathways, particularly downstream of mitochondria, determines the resultant pattern of cell death. The differential recruitment of specific death pathways depends on the timing of engagement of mitochondrial signalling. Other influences on programmed cell death pathways occur through stress of the endoplasmic reticulum and the associated ubiquitin-proteasome system normally handling potentially neurotoxic protein aggregates. Based upon contemporary evidence apoptosis is a relatively rare in the mature brain whereas the contribution of programmed necrosis to various neuropathologies has been underestimated. The death outcomes that neurones exhibit during acute or chronic injury or pathological conditions considered here (oxidative stress, hypoxic-ischaemic injury, amyotrophic lateral sclerosis, Parkinson's and Huntington's diseases) fall within a spectrum of the diverse death types across the apoptosis-necrosis continuum. Indeed, dying or dead neurones may simultaneously manifest characteristics of more than one type of death pathway. Understanding neuronal death pathways and their cross-talk not only informs the detailed pathobiology but also suggests novel therapeutic strategies.     

Xylem water-conducting patterns of 34 broadleaved evergreen trees in southern Japan

A dye injection method was used to elucidate the xylem water-conducting pathways of 34 broadleaved evergreen trees growing in southern Japan: two semi-ring-porous, 26 diffuse-porous, five radial-porous and one non-vessel species. The large earlywood vessels in semi-ring-porous species have a water transport function in only the outermost annual ring, as in deciduous ring-porous species. On the other hand, the small vessels in semi-ring-porous species maintain the water transport function in many outer annual rings. For the other xylem-type species, the many vessels in many outer annual rings have a water transport function. In diffuse-porous species, we categorized the water-conducting pattern within the annual rings into two types: d1 type, where water travels through vessels in the whole region; and d2 type, where water travels mainly through the earlywood vessels. The pattern in radial-porous species is similar to that in the d1 type; the pattern in non-vessels species is similar to that in the d2 type. The vessel diameter in radial-porous species is similar to that of the earlywood vessels of semi-ring-porous species. These results suggest that the conduit diameter size is only one of many factors determining the water-conducting pathways of broadleaved evergreen species.