The effect of resistant starch (RS) on the bovine rumen microflora and isolation of RS-degrading bacteria

Applied Microbiology and Biotechnology - Resistant starch (RS) in the diet reaches the large intestine without degradation, where it is decomposed by the commensal microbiota. The fermentation of...     

Sperm proteasomes degrade sperm receptor on the egg zona pellucida during mammalian fertilization

Despite decades of research, the mechanism by which the fertilizing spermatozoon penetrates the mammalian vitelline membrane, the zona pellucida (ZP) remains one of the unexplained fundamental events of human/mammalian development. Evidence has been accumulating in support of the 26S proteasome as a candidate for echinoderm, ascidian and mammalian egg coat lysin. Monitoring ZP protein degradation by sperm during fertilization is nearly impossible because those few spermatozoa that penetrate the ZP leave behind a virtually untraceable residue of degraded proteins. We have overcome this hurdle by designing an experimentally consistent in vitro system in which live boar spermatozoa are co-incubated with ZP-proteins (ZPP) solubilized from porcine oocytes. Using this assay, mimicking sperm-egg interactions, we demonstrate that the sperm-borne proteasomes can degrade the sperm receptor protein ZPC. Upon coincubation with motile spermatozoa, the solubilized ZPP, which appear to be ubiquitinated, adhered to sperm acrosomal caps and induced acrosomal exocytosis/formation of the acrosomal shroud. The degradation of the sperm receptor protein ZPC was assessed by Western blotting band-densitometry and proteomics. A nearly identical pattern of sperm receptor degradation, evident already within the first 5 min of coincubation, was observed when the spermatozoa were replaced with the isolated, enzymatically active, sperm-derived proteasomes. ZPC degradation was blocked by proteasomal inhibitors and accelerated by ubiquitin-aldehyde(UBAL), a modified ubiquitin protein that stimulates proteasomal proteolysis. Such a degradation pattern of ZPC is consistent with in vitro fertilization studies, in which proteasomal inhibitors completely blocked fertilization, and UBAL increased fertilization and polyspermy rates. Preincubation of intact zona-enclosed ova with isolated active sperm proteasomes caused digestion, abrasions and loosening of the exposed zonae, and significantly reduced the fertilization/polyspermy rates after IVF, accompanied by en-mass detachment of zona bound sperm. Thus, the sperm borne 26S proteasome is a candidate zona lysin in mammals. This new paradigm has implications for contraception and assisted reproductive technologies in humans, as well as animals.     

Postpartum Group Cohesion of Sympatric Deer in Texas

ABSTRACT Postpartum behavior of maternal deer may be specific to species of deer and predators. We captured sympatric white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus eremicus) fawns from radiocollared adult females in 2004–2006 on rangelands of west central Texas, USA, where predators larger than bobcats (Lynx rufus) were absent. Our objective was to determine whether differences in postpartum antipredator behavior existed between deer species, and if so, examine efficacy of those strategies. We collected postpartum group cohesion data in 2004 and 2005 by using radiotelemetry and examined dead fawns for cause of mortality. During fawns' hider phase, <3 weeks postpartum, mule deer females kept fawns closer to themselves (95% CI = 39−66 m) and twins closer to each other (95% CI = 25–49 m) than did white-tailed deer females (95% CIs = 152–234 m and 163–255 m, respectively). After 30 days postpartum, familial group cohesion was similarly tight for both species. During hider phases from 2004 to 2006, predated carcasses of white-tailed deer fawns (11 of 11) were dismembered or consumed more than mule deer fawns (7 of 13, P = 0.016), which was one line of evidence for maternal defense by mule deer adults. During hider phases in 2004 and 2005, predation rate of mule deer fawns was lower than that for white-tailed deer fawns. In 2006, predation rate increased for mule deer but was similar for white-tailed deer fawns compared with previous years. The tight cohesion strategy of mule deer exhibited in 2004 and 2005 seemed successful at thwarting small predators. Without large predators, the loose cohesion strategy of white-tailed deer females was maladaptive. When meso-predators are abundant due to extermination of larger predators, predation on fawns could increase if a deer species has relatively fixed postpartum maternal antipredator behavior.     

Inhibitors of hepatitis C virus NS3.4A protease 1. Non-charged tetrapeptide variants

Tetrapeptide-based peptidomimetic compounds have been shown to effectively inhibit the hepatitis C virus NS3.4A protease without the need of a charged functionality. An aldehyde is used as a prototype reversible electrophilic warhead. The SAR of the P1 and P2 inhibitor positions is discussed.     

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine

Rising global temperature and CO₂ levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO₂, affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L⁻¹) or elevated (800 μmol mol⁻¹) CO₂, and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO₂ (LTAC), elevated temperature/ambient CO₂ (ETAC), or elevated temperature/elevated CO₂ (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus. Our findings suggest that exposure to elevated temperature and CO₂ during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO₂ also impaired freezing tolerance. However, unless the frequency and timing of extreme low-temperature events changes, this is unlikely to increase risk of freezing damage in P. strobus seedlings.Land surface temperature is increasing, particularly in the northern hemisphere (IPCC, 2014), which is dominated by boreal and temperate forests. At higher latitudes, trees rely on temperature and photoperiod cues to detect changing seasons and to trigger cessation of growth and cold hardening during the autumn (Ensminger et al., 2015). For boreal and temperate evergreen conifers, cold hardening involves changes in carbohydrate metabolism, down-regulation of photosynthesis, accumulation of cryoprotective metabolites, and development of freezing tolerance (Crosatti et al., 2013; Ensminger et al., 2015). These processes minimize freezing damage and enable conifers to endure winter stresses. However, rising temperatures result in asynchronous phasing of temperature and photoperiod characterized by delayed arrival of first frosts (McMahon et al., 2010), which may impact the onset and development of cold hardening during autumn.Short photoperiod induces the cessation of growth in many tree species (Downs and Borthwick, 1956; Heide, 1974; Repo et al., 2000; Böhlenius et al., 2006). As a consequence, carbon demand in sink tissue decreases toward the end of the growing season, and the bulk of photoassimilate is translocated from source tissues to storage tissues (Hansen and Beck, 1994; Oleksyn et al., 2000). In addition, cryoprotective soluble sugars, including sucrose, raffinose, and pinitol, accumulate in leaf tissues to enhance freezing tolerance (Strimbeck et al., 2008; Angelcheva et al., 2014). Thus, by winter, leaf nonstructural carbohydrates are mainly comprised of mono- and oligosaccharides, and only minimal levels of starch remain (Hansen and Beck, 1994; Strimbeck et al., 2008). The concurrent decrease of photoassimilate and demand for metabolites that occur during the cessation of growth also impacts the citric acid cycle that mediates between photosynthesis, respiration, and protein synthesis. The citric acid cycle generates NADH to fuel ATP synthesis via mitochondrial electron transport, as well as amino acid precursors (Shi et al., 2015). In C3 plants, the enzyme phosphoenolpyruvate carboxylase (PEPC) converts phosphoenolpyruvate to oxaloacetic acid in order to supplement the flow of metabolites to the citric acid cycle and thus controls the regulation of respiration and photosynthate partitioning (O’Leary et al., 2011).Cessation of growth, low temperature, and presumably short photoperiod decrease the metabolic sink for photoassimilates, resulting in harmful excess light energy (Öquist and Huner, 2003; Ensminger et al., 2006) and increased generation of reactive oxygen species (Adams et al., 2004). During autumn and the development of cold hardiness, conifers reconfigure the photosynthetic apparatus in order to avoid formation of excess light and reactive oxygen species. This involves a decrease in chlorophylls and PSII reaction center core protein D1 (Ottander et al., 1995; Ensminger et al., 2004; Verhoeven et al., 2009), as well as aggregation of light-harvesting complex proteins (Ottander et al., 1995; Busch et al., 2007). Additionally, photoprotective carotenoid pigments accumulate in leaves, especially the xanthophylls, zeaxanthin, and lutein that contribute to nonphotochemical quenching (NPQ) via thermal dissipation of excess light energy (Busch et al., 2007; Verhoeven et al., 2009; Demmig-Adams et al., 2012). Prolonged exposure to low temperature induces sustained nonphotochemical quenching (NPQ_S), where zeaxanthin constitutively dissipates excess light energy (Ensminger et al., 2004; Demmig-Adams et al., 2012; Fréchette et al., 2015).In conifers, freezing tolerance is initiated during early autumn in response to decreasing photoperiod (Rostad et al., 2006; Chang et al., 2015) and continues to develop through late autumn in response to the combination of short photoperiod and low temperature (Strimbeck and Schaberg, 2009; Chang et al., 2015). In addition to changes in carbohydrate content, freezing tolerance also involves the expression of specific dehydrins (Close, 1997; Kjellsen et al., 2013). Members of the dehydrin protein family are involved in responses to osmotic, salt, and freezing stress (Close, 1996). Dehydrins have been associated with improved freezing tolerance in many species including spinach (Kaye et al., 1998), strawberry (Houde et al., 2004), cucumber (Yin et al., 2006), peach (Wisniewski et al., 1999), birch (Puhakainen et al., 2004), and spruce (Kjellsen et al., 2013). In angiosperms, a characteristic Lys-rich dehydrin motif known as the K-segment interacts with lipids to facilitate membrane binding (Koag et al., 2003; Eriksson et al., 2011). Several in vitro studies have demonstrated dehydrin functions including prevention of aggregation and unfolding of enzymes (using Vitis riparia; Hughes and Graether, 2011), radical scavenging (using Citrus unshiu; Hara et al., 2004), and suppression of ice crystal formation (using Prunus persica; Wisniewski et al., 1999). To date, dehydrin functions have not been demonstrated in planta.Rising temperatures since the mid-twentieth century have delayed the onset of autumn dormancy and increased length of the growing season in forests across the northern hemisphere (Boisvenue and Running, 2006; Piao et al., 2007; McMahon et al., 2010). Studies have shown that elevated temperatures ranging from +4°C to +20°C above ambient can delay down-regulation of photosynthesis in several evergreen conifers. Consistent findings were apparent among climate-controlled chamber studies exposing Pinus strobus seedlings to a sudden shift in temperature and/or photoperiod (Fréchette et al., 2016), as well as chamber studies exposing Picea abies seedlings to simulated autumn conditions using a gradient of decreasing temperature and photoperiod (Stinziano et al., 2015). Similar findings were also demonstrated in open-top chamber experiments exposing mature Pinus sylvestris to a gradient of decreasing temperature and natural photoperiod (Wang, 1996). Elevated temperature (+4°C above ambient) also impaired cold hardening in Pseudotsuga menziesii seedlings (Guak et al., 1998) and mature P. sylvestris (Repo et al., 1996) exposed to a decreasing gradient of temperature and natural photoperiod using open-top chambers. In contrast, a recent study showed that smaller temperature increments (+1.5°C to +3°C) applied using infrared heaters did not delay down-regulation of photosynthesis or impair freezing tolerance in field-grown P. strobus seedlings that were acclimated to larger diurnal and seasonal temperature variations (Chang et al., 2015). For many tree species, photoperiod determines cessation of growth (Tanino et al., 2010; Petterle et al., 2013), length of the growing season (Bauerle et al., 2012), and development of cold hardiness (Welling et al., 1997; Li et al., 2003; Rostad et al., 2006). However, the effects of climate warming on tree phenology are complex and can be unpredictable due to species- and provenance-specific differences in sensitivity to photoperiod and temperature cues (Körner and Basler, 2010; Basler and Körner, 2012; Basler and Körner, 2014).The effect of elevated CO₂ further increases uncertainties in the response of trees to warmer climate. Similar to warmer temperature, elevated CO₂ may also delay the down-regulation of photosynthesis in evergreens and extend the length of the growing season, as demonstrated in mature P. sylvestris (Wang, 1996). Elevated CO₂ increases carbon assimilation (Curtis and Wang, 1998; Ainsworth and Long, 2005) and biomass production (Ainsworth and Long, 2005) during the growing season. The effects could continue during the autumn if dormancy or growth cessation is delayed, which suggests that elevated CO₂ may increase annual carbon uptake. However, long-term exposure to elevated CO₂ can also down-regulate photosynthesis during the growing season (Ainsworth and Long, 2005). Prior studies that have attempted to determine the impact of a combination of elevated CO₂ and/or temperature on cold hardening in evergreens have largely focused on freezing tolerance, with contrasting results. Open-top chamber experiments showed that a combination of elevated temperature and CO₂ both delayed and impaired freezing tolerance of P. menziesii seedlings (Guak et al., 1998) and evergreen broadleaf Eucalyptus pauciflora seedlings (Loveys et al., 2006) but did not affect freezing tolerance of mature P. sylvestris (Repo et al., 1996). A recent field experiment examining mature trees revealed that Larix decidua, but not Pinus mugo, exhibited enhanced freezing damage following six years of exposure to combined soil warming and elevated CO₂ (Rixen et al., 2012). In contrast, a climate-controlled study showed that exposure to elevated CO₂ advanced the date of bud set and improved freezing tolerance in Picea mariana seedlings (Bigras and Bertrand, 2006). In a second study on similar seedlings conducted by the same authors, exposure of trees to elevated CO₂ also enhanced freezing tolerance but impaired the accumulation of sucrose and raffinose (Bertrand and Bigras, 2006). These previous experiments used experimental conditions where temperature and photoperiod gradually decreased. While this approach aims to mimic natural conditions, it is difficult to distinguish specific responses to either photoperiod or temperature. Because of the contrasting findings from previous studies, we designed an experiment aiming to separate the effects of photoperiod, temperature, and CO₂ on a wide range of parameters that are involved in cold hardening in conifers.Our study aimed to determine (1) how induction and development of the cold hardening process is affected by a shift from long to short photoperiod under warm conditions and (2) how the combination of warm air temperature and elevated CO₂ affects photoperiod-induced cold hardening processes in Eastern white pine (P. strobus). To assess the development of cold hardening, we measured photosynthetic rates, changes in leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening over 36 d. Assuming that both low temperature and short photoperiod cues are required to induce cold hardening in conifers, we hypothesized that warm temperature and the combination of warm temperature and elevated CO₂ would prevent seedlings growing under autumn photoperiod from down-regulating photosynthesis. We further hypothesized that warm temperature and the combination of warm temperature and elevated CO₂ would impair the development of freezing tolerance, due to a lack of adequate phasing of the low temperature and short photoperiod signals.     

Psoriatic arthritis and sacroiliitis are associated with increased vascular inflammation by 18-fluorodeoxyglucose positron emission tomography computed tomography: baseline report from the Psoriasis Atherosclerosis and Cardiometabolic Disease Initiative

Introduction

Psoriasis and psoriatic arthritis (PsA) increase cardiovascular disease (CVD) risk, but surrogate markers for CVD in these disorders are inadequate. Because the presence of sacroiliitis may portend more severe PsA, we hypothesized that sacroiliitis defined by computed tomography (CT) would be associated with increased vascular inflammation defined by 18-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT), which is an established measure of CVD.

Methods

Participants (n = 65) underwent whole-body FDG-PET/CT. Metabolic activity of the aorta was measured using the maximal standardized uptake value (SUV_max), a measure of atherosclerotic plaque activity. The primary outcome was aortic vascular inflammation. Linear regression (with β-coefficients (β) and P-values reported for PsA and sacroiliitis) was used to adjust for CVD risk factors to determine associations of PsA or sacroiliitis with vascular inflammation. Likelihood ratio testing was performed to evaluate the contribution of sacroiliitis to vascular disease estimation compared to the effects of PsA and traditional CVD risk factors.

Results

Vascular inflammation (measured as SUV_max) was greater (P < 0.001) in patients with sacroiliitis (mean ± SD = 7.33 ± 2.09) defined by CT compared to those without sacroiliitis (6.39 ± 1.49, P = 0.038). There were associations between PsA and aortic inflammation (β = 0.124, P < 0.001) and between sacroiliitis and aortic inflammation (β = 0.270, P < 0.001) after adjusting for CVD risk factors. Sacroiliitis predicted vascular inflammation beyond PsA and CVD risk factors (χ² = 124.6, P < 0.001).

Conclusions

Sacroiliitis is associated with increased vascular inflammation detected by FDG-PET/CT, suggesting that sacroiliac joint disease may identify patients at greater risk for CVD. Large, ongoing prospective studies are required to confirm these findings.

Electronic supplementary material

The online version of this article (doi:10.1186/ar4676) contains supplementary material, which is available to authorized users.     

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.     

Ceftriaxone increases glutamate uptake and reduces striatal tyrosine hydroxylase loss in 6-OHDA Parkinson's model

Excess glutamatergic neurotransmission may contribute to excitotoxic loss of nigrostriatal neurons in Parkinson's disease (PD). Here, we determined if increasing glutamate uptake could reduce the extent of tyrosine hydroxylase (TH) loss in PD progression. The beta-lactam antibiotic, ceftriaxone, increases the expression of glutamate transporter 1 (GLT-1), a glutamate transporter that plays a major role in glutamate clearance in central nervous system and may attenuate adverse behavioral or neurobiological function in other neurodegenerative disease models. In association with >80 % TH loss, we observed a significant decrease in glutamate uptake in the established 6-hydroxydopamine (6-OHDA) PD model. Ceftriaxone (200 mg/kg, i.p.) increased striatal glutamate uptake with >5 consecutive days of injection in nonlesioned rats and lasted out to 14 days postinjection, a time beyond that required for 6-OHDA to produce >70 % TH loss (～9 days). When ceftriaxone was given at the time of 6-OHDA, TH loss was ～57 % compared to ～85 % in temporally matched vehicle-injected controls and amphetamine-induced rotation was reduced about 2-fold. This attenuation of TH loss was associated with increased glutamate uptake, increased GLT-1 expression, and reduced Serine 19 TH phosphorylation, a calcium-dependent target specific for nigrostriatal neurons. These results reveal that glutamate uptake can be targeted in a PD model, decrease the rate of TH loss in a calcium-dependent manner, and attenuate locomotor behavior associated with 6-OHDA lesion. Given that detection of reliable PD markers will eventually be employed in susceptible populations, our results give credence to the possibility that increasing glutamate uptake may prolong the time period before locomotor impairment occurs.