Maintenance of surrogate light chain expression induces developmental delay in early B cell compartment

The production of a mature B cell requires passage through a number of developmental checkpoints. The pre-BCR plays a critical role in passage through the pro-B cell/pre-B cell checkpoint, and thus plays a central role in regulating the differentiation of a B cell. Due to the significance of this receptor, it is imperative that pre-BCR expression and function are precisely regulated. In this study, we have investigated a system in which the regulation of the pre-BCR is altered. We have found that continued expression of components of the pre-BCR (lambda5) resulted in a delay in the kinetics of B cell maturation. Pro-B cells from normal mouse bone marrow retrovirally infected with lambda5 exhibited a delay in differentiation. As compared with wild-type cells at the same time point, there is a reduction in the presence of cell surface markers that indicate developmental progression, and there is a 6- to 16-fold decrease in the production of Ig-positive cells in B cell maturation assays. The capacity to alter B cell progression by modifying and extending pre-BCR expression argues that the receptor and its associated signals play a unique role in directing developmental outcomes.     

Loss of SLC38A5 and FTSJ1 at Xp11.23 in three brothers with non-syndromic mental retardation due to a microdeletion in an unstable genomic region

Using high resolution X chromosome array-CGH we identified an interstitial microdeletion at Xp11.23 in three brothers with moderate to severe mental retardation (MR) without dysmorphic features. The extent of the deletion was subsequently delineated to about 50 kb by regular PCR and included only the SLC38A5 and FTSJ1 genes. The loss of the FTSJ1 MR gene in males is expected to result in the observed phenotype but the contribution of the deletion of the solute carrier SLC38A5 gene is less clear. Their mother also carries the deletion and completely inactivates the aberrant X chromosome. Interestingly, the distal breakpoint is situated within a 200 kb SSX repeat region that appears to stimulate recombination since subtle copy number changes often occur at this location and it is frequently involved in translocations in tumours. Since this apparent SSX unstable structure is flanked proximally by FTSJ1 and PQBP1, subtle deletions or duplications at this location would be expected to cause MR, as in our family. So far, we have screened a cohort of 300 patients but did not find additional aberrations at the FTSJ1 locus indicating that the frequency is likely to be low.     

Abnormal adaptive face-coding mechanisms in children with autism spectrum disorder

In low-level vision, exquisite sensitivity to variation in luminance is achieved by adaptive mechanisms that adjust neural sensitivity to the prevailing luminance level. In high-level vision, adaptive mechanisms contribute to our remarkable ability to distinguish thousands of similar faces [1]. A clear example of this sort of adaptive coding is the face-identity aftereffect [2, 3, 4, 5], in which adaptation to a particular face biases perception toward the opposite identity. Here we investigated face adaptation in children with autism spectrum disorder (ASD) by asking them to discriminate between two face identities, with and without prior adaptation to opposite-identity faces. The ASD group discriminated the identities with the same precision as did the age- and ability-matched control group, showing that face identification per se was unimpaired. However, children with ASD showed significantly less adaptation than did their typical peers, with the amount of adaptation correlating significantly with current symptomatology, and face aftereffects of children with elevated symptoms only one third those of controls. These results show that although children with ASD can learn a simple discrimination between two identities, adaptive face-coding mechanisms are severely compromised, offering a new explanation for previously reported face-perception difficulties [6, 7, 8] and possibly for some of the core social deficits in ASD [9, 10].     

Turning the other cheek: the viewpoint dependence of facial expression after-effects

How do we visually encode facial expressions? Is this done by viewpoint-dependent mechanisms representing facial expressions as two-dimensional templates or do we build more complex viewpoint independent three-dimensional representations? Recent facial adaptation techniques offer a powerful way to address these questions. Prolonged viewing of a stimulus (adaptation) changes the perception of subsequently viewed stimuli (an after-effect). Adaptation to a particular attribute is believed to target those neural mechanisms encoding that attribute. We gathered images of facial expressions taken simultaneously from five different viewpoints evenly spread from the three-quarter leftward to the three-quarter rightward facing view. We measured the strength of expression after-effects as a function of the difference between adaptation and test viewpoints. Our data show that, although there is a decrease in after-effect over test viewpoint, there remains a substantial after-effect when adapt and test are at differing three-quarter views. We take these results to indicate that neural systems encoding facial expressions contain a mixture of viewpoint-dependent and viewpoint-independent elements. This accords with evidence from single cell recording studies in macaque and is consonant with a view in which viewpoint-independent expression encoding arises from a combination of view-dependent expression-sensitive responses.     

Familiarization and reliability of multiple sprint running performance indices

The aims of this study were to evaluate the time-course of the familiarization process associated with a test of multiple sprint running performance and to determine the reliability of various performance indices once familiarization had been established. Eleven physically active men (mean age: 21 +/- 2 years) completed 4 multiple sprint running trials (12 x 30 m; repeated at 35-s intervals) with 7 days between trials. All testing was conducted indoors, and times were recorded by twin-beam photocells. Results revealed no apparent learning effects as evidenced by no significant (p > 0.05) between-trial differences in measures of fastest or mean 30-m sprint time. Within-subject test-retest reliability determined over 4 trials by coefficient of variation (CV) and intraclass correlation coefficient (ICC) showed excellent reliability for measures of fastest and mean sprint times (CV range: 1.34-2.24%; ICC range: 0.79-0.94). Pre- and posttrial blood lactate concentrations showed good reliability when judged in context with typical values (CV range: 12.08-18.21%; ICC range: 0.72-0.78). In contrast, and in line with previous research, fatigue data showed much greater variability (CV: 26.43%; ICC: 0.66). The results of this study suggest that high degrees of test-retest reliability can be obtained in many multiple sprint running indices without the need for prior familiarization.     

Multimeric HCV E2 protein obtained from <Emphasis Type="Italic">pichia pastoris</Emphasis> cells induces a strong immune response in mice

Production of immunogenic hepatitis C virus (HCV) envelope proteins will assist in the future development of preventive or therapeutics applications. Only properly folded monomeric E2 protein is able to bind a putative cellular co-receptor CD81, but this interaction may modulate cell immune function. Recombinant E2 proteins, similar to the native form, but lacking undesirable immunoregulatory features, might be promising components of vaccine candidates against HCV. To obtain E2 suitable for structural as well as functional studies, a recombinant E2 variant (E2₆₈₀) was produced in Pichia pastoris cells. E2₆₈₀, comprising amino acids 384 to 680 of the HCV polyprotein, was secreted into the culture supernatant in the N-glycosilated form and was mainly composed of disulide-linked multimers. Both monomeric and oligomeric forms of E2₆₈₀ were recognized by conformational-sensitive MAb H53. In addition, antibodies in sera from 70% of HCV-positive patients were reactive against E2₆₈₀. By immunizing E2₆₈₀ in BALB/c mice, both a specific cellular immune response and anti-E2₆₈₀ IgG antibody titers of 1:200,000 were induced. Our data suggest that recombinant E2₆₈₀ could be useful to successfully induce strong anti-HCV immunity.     

Rivers in peril inside and outside protected areas: a systematic approach to conservation assessment of river ecosystems

This paper establishes a framework within which a rapid and pragmatic assessment of river ecosystems can be undertaken at a broad, subcontinental scale, highlighting some implications for achieving conservation of river biodiversity in water‐limited countries. The status of river ecosystems associated with main rivers in South Africa was assessed based on the extent to which each ecosystem had been altered from its natural condition. This requires consistent data on river integrity for the entire country, which was only available for main rivers; tributaries were thus excluded from the analyses. The state of main river ecosystems in South Africa is dire: 84% of the ecosystems are threatened, with a disturbing 54% critically endangered, 18% endangered, and 12% vulnerable. Protection levels were measured as the proportion of conservation target achieved within protected areas, where the conservation target was set as 20% of the total length of each river ecosystem. Sixteen of the 112 main river ecosystems are moderately to well represented within protected areas; the majority of the ecosystems have very low levels of representation, or are not represented at all within protected areas. Only 50% of rivers within protected areas are intact, but this is a higher proportion compared to rivers outside (28%), providing some of the first quantitative data on the positive role protected areas can play in conserving river ecosystems. This is also the first assessment of river ecosystems in South Africa to apply a similar approach to parallel assessments of terrestrial, marine, and estuarine ecosystems, and it revealed that main river ecosystems are in a critical state, far worse than terrestrial ecosystems. Ecosystem status is likely to differ with the inclusion of tributaries, since options may well exist for conserving critically endangered ecosystems in intact tributaries, which are generally less regulated than main rivers. This study highlights the importance of healthy tributaries for achieving river conservation targets, and the need for managing main rivers as conduits across the landscape to support ecological processes that depend on connectivity. We also highlight the need for a paradigm shift in the way protected areas are designated, as well as the need for integrated river basin management plans to include explicit conservation visions, targets, and strategies to ensure the conservation of freshwater ecosystems and the services they provide.     

Use of crowdsourced images for determining 2D:4D and relationship to pro-environmental variables

acta ethologica - The primary purpose of this study was to examine whether 2D:4D ratios (a putative measure of prenatal androgen exposure) could be determined using participant-submitted hand...     

Unidirectional Movement of Cellulose Synthase Complexes in Arabidopsis Seed Coat Epidermal Cells Deposit Cellulose Involved in Mucilage Extrusion,Adherence, and Ray Formation

CELLULOSE SYNTHASE5 (CESA5) synthesizes cellulose necessary for seed mucilage adherence to seed coat epidermal cells of Arabidopsis (Arabidopsis thaliana). The involvement of additional CESA proteins in this process and details concerning the manner in which cellulose is deposited in the mucilage pocket are unknown. Here, we show that both CESA3 and CESA10 are highly expressed in this cell type at the time of mucilage synthesis and localize to the plasma membrane adjacent to the mucilage pocket. The isoxaben resistant1-1 and isoxaben resistant1-2 mutants affecting CESA3 show defects consistent with altered mucilage cellulose biosynthesis. CESA3 can interact with CESA5 in vitro, and green fluorescent protein-tagged CESA5, CESA3, and CESA10 proteins move in a linear, unidirectional fashion around the cytoplasmic column of the cell, parallel with the surface of the seed, in a pattern similar to that of cortical microtubules. Consistent with this movement, cytological evidence suggests that the mucilage is coiled around the columella and unwinds during mucilage extrusion to form a linear ray. Mutations in CESA5 and CESA3 affect the speed of mucilage extrusion and mucilage adherence. These findings imply that cellulose fibrils are synthesized in an ordered helical array around the columella, providing a distinct structure to the mucilage that is important for both mucilage extrusion and adherence.The epidermal cells of Arabidopsis (Arabidopsis thaliana) seed coats produce two distinct secondary cell walls: pectin-rich mucilage and cellulose-rich columellae (Western et al., 2000). When seeds are hydrated, mucilage expands rapidly, rupturing the outer tangential cell wall and forming a mucilage capsule that surrounds the seed. Seed coat mucilage is composed primarily of rhamnogalacturonan I (RG I) and also contains homogalacturonan (HG), hemicelluloses (such as xylans and glucomannans), and cellulose (for review, see Haughn and Western, 2012). Extruded mucilage consists of an outer, nonadherent fraction and an inner, adherent fraction (Western et al., 2000, 2001; Macquet et al., 2007a). The adherent and nonadherent mucilage layers differ in the amount of methylesterified HG (Rautengarten et al., 2008; Saez-Aguayo et al., 2013; Voiniciuc et al., 2013), galactans (Dean et al., 2007; Macquet et al., 2007b), arabinans (Arsovski et al., 2009), mannans (Yu et al., 2014), and cellulose (Harpaz-Saad et al., 2011; Mendu et al., 2011; Sullivan et al., 2011), all of which influence the physical properties of the layers.Adherent mucilage has a distinct structure, which can be examined using cell wall dyes and antibodies. When treated with cellulose-specific dyes, densely stained rays extend from the top of each columella to the outer edge of the adherent layer, many cell lengths above the seed surface (Mendu et al., 2011; Sullivan et al., 2011). Cytological evidence indicates that cellulose, pectins, and mannans are components of the ray (Haughn and Western, 2012; Griffiths et al., 2014; North et al., 2014; Yu et al., 2014), although the exact manner in which they are assembled is unknown.Cellulose is abundant in mucilage rays and mediates adherence. Loss-of-function mutations in CELLULOSE SYNTHASE5 (CESA5) result in reduced cellulose levels and increased detachment of mucilage from the seed (Harpaz-Saad et al., 2011; Mendu et al., 2011; Sullivan et al., 2011; Griffiths et al., 2014). How a reduction in cellulose results in a loss of adherence is still unknown, but it likely involves interaction with other mucilage components such as pectin and arabinogalactan proteins (Griffiths et al., 2014). Since cesa5 mutants still have some cellulose in the rays of the adherent mucilage halo (Mendu et al., 2011; Sullivan et al., 2011), additional cellulose synthases must be involved in mucilage cellulose biosynthesis.The Arabidopsis genome encodes 10 different CESAs (Delmer, 1999; Richmond and Somerville, 2000). Multiple lines of evidence suggest that three different CESAs are required to form one active cellulose synthase complex (CSC; for review, see Somerville, 2006). CSCs are membrane-bound protein complexes that synthesize cellulose microfibrils in the apoplast (for review, see Somerville, 2006; Endler and Persson, 2011; Lei et al., 2012). CESA1, CESA3, and CESA6 are considered the core components of the primary wall CSC (Desprez et al., 2007; Persson et al., 2007). CESA2, CESA5, and CESA9 are partially redundant to CESA6 in primary wall biosynthesis, and genetic evidence suggests that each of these CESA polypeptides can form a functional CSC with CESA3 and CESA1 (Desprez et al., 2007; Persson et al., 2007). CESA10 is expressed in young plants, stems, floral tissue, and the base of rosette leaves (Beeckman et al., 2002; Doblin et al., 2002), but its function in cellulose biosynthesis is unclear. Other cesa mutant lines have been examined for altered mucilage phenotypes (cesa1, radially swollen1 [Burn et al., 2002; Sullivan et al., 2011], cesa2, cesa6, and cesa9 [Mendu et al., 2011]; CESA3, je5 [Sullivan et al., 2011] and cesa10-1 [Sullivan et al., 2011]); to date, only CESA5 has been shown to be required for cellulose biosynthesis during mucilage deposition.Two mutant alleles of CESA3, isoxaben resistant1-1 (ixr1-1) and ixr1-2, were isolated in a screen for resistance to the herbicide isoxaben (Scheible et al., 2001). Isoxaben inhibits the incorporation of Glc into the emerging cellulose polymer and is considered a potent and specific inhibitor of cellulose biosynthesis (Heim et al., 1990). Homozygous ixr1-1 and ixr1-2 lines show increased resistance to the herbicide, and the mutations causing this resistance were mapped to the genomic locus of CESA3 (Heim et al., 1990; Scheible et al., 2001). The ixr1-1 and ixr1-2 mutations cause amino acid substitutions near the C terminus of the CESA3 protein. ixr1-1 causes a Gly-to-Asn substitution (G998A) located in a transmembrane domain, while ixr1-2 contains a Thr-to-Ile substitution (T942I) in an apoplastic region of the protein between two transmembrane domains (Scheible et al., 2001). Recently, the ixr1-2 allele was shown to affect the velocity of CSCs in the plasma membrane, which consequently modifies cellulose crystallinity in the cell wall (Harris et al., 2012). It is not exactly clear how the ixr1-1 mutation affects cellulose biosynthesis. The effects of either of these mutations on seed coat mucilage have not been investigated.Since mucilage is composed primarily of pectins with smaller amounts of cellulose, seed coat epidermal cells represent an excellent system to study cellulose biosynthesis and interactions between cellulose and other wall components in muro. In this study, we investigated how cellulose is synthesized and deposited in seed coat epidermal cells. We show that at least three different CESA proteins are highly expressed in the seed coat epidermis during mucilage biosynthesis. These CESAs are oriented and move in a linear fashion around the cytoplasmic column of each cell in an identical pattern to cortical microtubules. In addition, we provide evidence that the adherent mucilage has a helical structure that expands and unwinds during extrusion to form the mucilage ray. We propose that during seed coat epidermal cell development, the biosynthesis of cellulose predetermines the structure of rays in the adherent mucilage layer.