Alteration of the nucleosomal DNA path in the crystal structure of a human nucleosome core particle

Gene expression in eukaryotes depends upon positioning, mobility and packaging of nucleosomes; thus, we need the detailed information of the human nucleosome core particle (NCP) structure, which could clarify chromatin properties. Here, we report the 2.5 Å crystal structure of a human NCP. The overall structure is similar to those of other NCPs reported previously. However, the DNA path of human NCP is remarkably different from that taken within other NCPs with an identical DNA sequence. A comparison of the structural parameters between human and Xenopus laevis DNA reveals that the DNA path of human NCP consecutively shifts by 1 bp in the regions of superhelix axis location −5.0 to −2.0 and 5.0 to 7.0. This alteration of the human DNA path is caused predominantly by tight DNA–DNA contacts within the crystal. It is also likely that the conformational change in the human H2B tail induces the local alteration of the DNA path. In human NCP, the region with the altered DNA path lacks Mn(2+) ions and the B-factors of the DNA phosphate groups are substantially high. Therefore, in contrast to the histone octamer, the nucleosomal DNA is sufficiently flexible and mobile and can undergo drastic conformational changes, depending upon the environment

The Architecture of the Cytoplasmic Region of Type III Secretion Systems

Type III secretion systems (T3SSs) are essential devices in the virulence of many Gram-negative bacterial pathogens. They mediate injection of protein effectors of virulence from bacteria into eukaryotic host cells to manipulate them during infection. T3SSs involved in virulence (vT3SSs) are evolutionarily related to bacterial flagellar protein export apparatuses (fT3SSs), which are essential for flagellar assembly and cell motility. The structure of the external and transmembrane parts of both fT3SS and vT3SS is increasingly well-defined. However, the arrangement of their cytoplasmic and inner membrane export apparatuses is much less clear. Here we compare the architecture of the cytoplasmic regions of the vT3SSs of Shigella flexneri and the vT3SS and fT3SS of Salmonella enterica serovar Typhimurium at ~5 and ~4 nm resolution using electron cryotomography and subtomogram averaging. We show that the cytoplasmic regions of vT3SSs display conserved six-fold symmetric features including pods, linkers and an ATPase complex, while fT3SSs probably only display six-fold symmetry in their ATPase region. We also identify other morphological differences between vT3SSs and fT3SSs, such as relative disposition of their inner membrane-attached export platform, C-ring/pods and ATPase complex. Finally, using classification, we find that both types of apparatuses can loose elements of their cytoplasmic region, which may therefore be dynamic

AMH Concentrations in Peritoneal Fluids of Women With and Without Endometriosis

Background: As its name indicates, anti-Mullerian hormone (AMH) is primarily found as an inhibitor of the Mullerian duct in male fetus. On the other hand, AMH may act as a mediator of Mullerian duct-derived female tissue, such as endometrium in normal and pathological conditions. However, the role of AMH in the functional regulations of endometriosis is not well understood. It can be hypothesized that AMH in peritoneal fluids may affect the activity of peritoneal endometriosis. In this study, we investigated the levels of AMH in peritoneal fluids (PF) in women with and without endometriosis. Methods: PF were collected during laparoscopy from 90 women diagnosed as having advanced endometriosis (rASRM stage III, n = 30; stage IV, n = 60), and 32 women without endometriosis were served as control. Paired serum samples were also collected before the surgery. AMH in PF and serum were measured by ELISA. Individual clinical information was collected. AMH levels were compared according to the presence of endometriosis. The expression of AMHR2 in peritoneal endometriotic lesions obtained during laparoscopy was examined by immunohistochemistry. Results: AMH levels in PF were positively and significantly correlated with serum AMH levels in both women with and without endometriosis (R2 = 0.17, P < 0.0001; R2 = 0.30, P = 0.001, respectively). Serum AMH levels were inversely and significantly correlated with age in women with endometriosis (R2 = 0.092, P = 0.004) and in control women without statistical significance (R2 = 0.078, P = 0.12). AMH levels in PF were also inversely but not significantly correlated with age in women with and without endometriosis (R2 = 0.029, P = 0.11 and R2 = 0.027, P = 0.37, respectively). Mean age and serum AMH levels were not significantly different between two groups. On the other hand, AMH levels in PF were significantly lower in women with endometriosis compared to those of control women [2.15 ± 2.13 (mean ± SD) vs. 4.40 ± 4.77 ng/mL, P = 0.0001]. AMHR2 are localized at glandular epithelium and stromal cells in the ectopic endometrium of peritoneal endometriosis. Conclusions: Women with endometriosis may present lower PF AMH levels even if they retain serum levels similar to women without disease. As peritoneal endometriosis expresses a specific receptor for AMH, lower AMH levels in PF of women with advanced endometriosis may be involved in the pathophysiology of peritoneal endometriosis

Accumulation of fibrosis and altered perifollicular stromal differentiation in vitrified‐thawed human ovarian tissue xenografted to nude mice.

Purpose: Ovarian tissue cryopreservation and its auto-transplantation is promising technique in fertility preservation. Longevity of grafted tissue is limited though mechanism of follicle reduction is not fully understood. We evaluated histological alteration of vitrified-thawed ovarian tissue that grafted to nude mice. Materials and Methods: Human ovarian tissue was cryopreserved by vitrification. After thawing, they were grafted to mesentery of nude mice. Twelve weeks after transplantation, the implants were removed and histologically examined. The presence of follicles, the degree of fibrosis, and TUNEL staining in surrounding cortex were evaluated. The stromal expressions of alpha-smooth muscle actin (aSMA) were determined.Results: Normal ovarian cortex was decreased, and fibrotic area were significantly increased after grafting. The distributions of developmental stage of follicles shifted toward activation of follicular growth. Stromal TUNEL staining was increased in frozen/thawed tissue. The expression of aSMA were found in perifollicular stroma of growing follicles, which were decreased in grafted tissue associated with reduction of cortical stroma.Conclusions: Fibrosis, reduced cortical stroma, and activation of dormant follicleswere concomitantly observed in grafted ovarian cortex, which may relate to limited longevity. Perifollicular aSMA expression can be regarded as a marker of the competence of cortical stroma that regulate follicular development

AMH producing purely cystic virilizing adult granulosa cell tumor in 17 years old girl: a case report and review of literatures

Background: Androgen-producing granulosa cell tumor in adolescent girl is rare condition and clinical characteristics are not fully elucidated. Case presentation: Seventeen years old girl complained of secondary amenorrhea was referred to our out-patient consultation. Markedly elevated serum testosterone, LH, and AMH levels were noted. Mild hirsutism and clitoromegaly were presented. Transabdominal ultrasonography and MRI revealed cystic mass occupied pelvic cavity probably originated from left ovary. Right ovary showed polycystic appearance. Laparoscopic left ovarian cystectomy was performed. After the surgery, her menstruation resumed along with normalized hormonal parameters, and clinical hyperandrogenism were improved. Since the scarcity of cellular lining of inner cyst wall, definitive pathological diagnosis was difficult. After the consultation with gynecological pathologist, the tumor was diagnosed as sex cord stromal tumor, highly suspicious for adult granulosa cell tumor. Residual left salpingo-oophorectomy was performed by additional laparoscopic surgery. Her serum testosterone and AMH levels were remained low with regular menstrual cycles and no evidence of recurrence. Conclusions: Androgen-producing cystic granulosa cell tumor is rare gynecological disorders, which need both gynecologic oncological and endocrinological approach. Its clinical manifestations may bring some clues to the pathogenesis of ovulatory dysfunctions, such as polycystic ovary syndrome

Putative Neural Network Within an Olfactory Sensory Unit for Nestmate and Non-nestmate Discrimination in the Japanese Carpenter Ant: The Ultra-structures and Mathematical Simulation

Ants are known to use a colony-specific blend of cuticular hydrocarbons (CHCs) as a pheromone to discriminate between nestmates and non-nestmates and the CHCs were sensed in the basiconic type of antennal sensilla (S. basiconica). To investigate the functional design of this type of antennal sensilla, we observed the ultra-structures at 2D and 3D in the Japanese carpenter ant, Camponotus japonicus, using a serial block-face scanning electron microscope (SBF-SEM), and conventional and high-voltage transmission electron microscopes. Based on the serial images of 352 cross sections of SBF-SEM, we reconstructed a 3D model of the sensillum revealing that each S. basiconica houses &gt; 100 unbranched dendritic processes, which extend from the same number of olfactory receptor neurons (ORNs). The dendritic processes had characteristic beaded-structures and formed a twisted bundle within the sensillum. At the “beads,” the cell membranes of the processes were closely adjacent in the interdigitated profiles, suggesting functional interactions via gap junctions (GJs). Immunohistochemistry with anti-innexin (invertebrate GJ protein) antisera revealed positive labeling in the antennae of C. japonicus. Innexin 3, one of the five antennal innexin subtypes, was detected as a dotted signal within the S. basiconica as a sensory organ for nestmate recognition. These morphological results suggest that ORNs form an electrical network via GJs between dendritic processes. We were unable to functionally certify the electric connections in an olfactory sensory unit comprising such multiple ORNs; however, with the aid of simulation of a mathematical model, we examined the putative function of this novel chemosensory information network, which possibly contributes to the distinct discrimination of colony-specific blends of CHCs or other odor detection

Effects of C-terminal Truncation of Chaperonin GroEL on the Yield of In-cage Folding of the Green Fluorescent Protein.

Chaperonin GroEL from Escherichia coli consists of two heptameric rings stacked back-to-back to form a cagelike structure. It assists in the folding of substrate proteins in concert with the co-chaperonin GroES by incorporating them into its large cavity. The mechanism underlying the incorporation of substrate proteins currently remains unclear. The flexible C-terminal residues of GroEL, which are invisible in the x-ray crystal structure, have recently been suggested to play a key role in the efficient encapsulation of substrates. These C-terminal regions have also been suggested to separate the double rings of GroEL at the bottom of the cavity. To elucidate the role of the C-terminal regions of GroEL on the efficient encapsulation of substrate proteins, we herein investigated the effects of C-terminal truncation on GroE-mediated folding using the green fluorescent protein (GFP) as a substrate. We demonstrated that the yield of in-cage folding mediated by a single ring GroEL (SR1) was markedly decreased by truncation, whereas that mediated by a double ring football-shaped complex was not affected. These results suggest that the C-terminal region of GroEL functions as a barrier between rings, preventing the leakage of GFP through the bottom space of the cage. We also found that once GFP folded into its native conformation within the cavity of SR1 it never escaped even in the absence of the C-terminal tails. This suggests that GFP molecules escaped through the pore only when they adopted a denatured conformation. Therefore, the folding and escape of GFP from C-terminally truncated SR1·GroES appeared to be competing with each other

Ultrastructural study of plasmodesmata in the brown alga Dictyota dichotoma (Dictyotales, Phaeophyceae)

Plasmodesmata (PD) singular: plasmodesma, from the Greek plasma=cytoplasm and desmos=connection) are intercellular bridges of multicellular plants, directly connecting cytoplasms of neighboring cells. They play a crucial role in cell-to-cell communication and cell development. Although brown algae (Phaeophyceae, Heterokontophyta) are phylogenetically far from the lineage of land plants, they possess a complex multicellularity with PD like green plants. In this study, the ultrastructure and the formation of PD in the brown alga Dictyota dichotoma, were studied using transmission electron microscopy (TEM) and electron tomography with rapid freezing and freeze-substitution. D. dichotoma, possesses plasma membrane-lined simple PD without an internal endoplasmic reticulum (ER) (desmotubule), different from those of land plants. PD were clustered in thin cell wall regions forming pit fields. Fine proteinaceous internal bridges were observed in the cavity. Ultrastructural observations of cytokinesis of D. dichotoma revealed that the PD formation started from an early stage of cytokinesis with the formation of tubular pre-plasmodesmata (PPD) within the membranous sacs (MSs) of the cytokinetic diaphragm. Clustering of these PPD became into the future pit field. As cytokinesis proceeds, electron-dense material extended from the outer surface of the middle part of PPD and finally formed the nascent cell wall. From these results, it is suggested that PPD would be associated with the cell wall development during cytokinesis of D. dichotroma