Alien pollen grains interfere with the reproductive success of native congener

The effects of invasive species on native species comprise important conservation issues. Determining the mechanisms by which invasives exclude natives is indispensable to efficiently control their impact, but most invasives remain poorly studied. The purpose of this study was to elucidate potentially important but neglected mechanisms, reproductive interference, in wild Taraxacum systems, in which invasive Taraxacum officinale has displaced its native congener T. japonicum in Japan. Hand-pollination of mixed pollen grains significantly reduced the native seed-set compared to conspecific-only pollination. Moreover, natives with a high ratio of invasive pollen on their stigmas suffered severe seed-set reduction, and the proportion of invasive pollen on native stigmas increased as frequencies of the alien neighbor increased. These results, combined with those of previous studies, revealed that depositing invasive pollen on native stigmas contributes to the observed alien-frequency-dependent reduction of native seed-set, and strongly suggest that reproductive interference was the primary cause of displacement in the Taraxacum systems.     

The effects of refreezing on the viscoelastic and tensile properties of ligaments

Biomechanical testing protocols for ligaments can be extensive and span two or more days. During this time, a specimen may have to undergo more than one cycle of freezing and thawing. Thus, the objective of this study was to evaluate the effects of refreezing on the viscoelastic and tensile properties of ligaments. The femur-medial collateral ligament-tibia complexes (FMTC) from six pairs of rabbit knees were used for this study. Following sacrifice, one leg in each pair was assigned to the fresh group and the FMTC was immediately dissected and prepared for testing. The contralateral knees were fresh-frozen at -20 degrees C for 3 weeks, thawed, dissected and then refrozen for one additional week before being tested as the refrozen group. The cross-sectional area and shape of the medial collateral ligament (MCL) was measured using a laser micrometer system. Stress relaxation and cyclic stress-relaxation tests in uniaxial tension were performed followed by a load to failure test. When the viscoelastic behavior of the MCL was described by the quasi-linear viscoelastic (QLV) theory, no statistically significant differences could be detected for the five constants (A, B, C, tau1, and tau2) between the fresh and refrozen groups (p > or = 0.07) based on our sample size. In addition, the structural properties of the FMTCs and the mechanical properties of the MCLs were also found to be similar between the two groups (p > or = 0.68). These results suggest that careful refreezing of the specimens had little or no effect on the biomechanical properties measured.     

Cytokeratin 18 is a specific marker of bovine intestinal M cell

Microfold (M) cells in the follicle-associated epithelium (FAE) of Peyer's patches have an important role in mucosal immune responses. A primary difficulty for investigations of bovine M cells is the lack of a specific molecular marker. To identify such a marker, we investigated the expression of several kinds of intermediate filament proteins using calf Peyer's patches. The expression patterns of cytokeratin (CK) 18 in jejunal and ileal FAE were very similar to the localization pattern of M cells recognized by scanning electron microscopy. Mirror sections revealed that jejunal CK18-positive cells had irregular and sparse microvilli, as well as pocket-like structures containing lymphocytes, typical morphological characteristic of M cells. However, CK18-negative cells had regular and dense microvilli on their surface, typical of the morphology of enterocytes. In contrast, CK20 immunoreactivity was detected in almost all villous epithelial cells and CK18-negative cells in the FAE. CK18-positive proliferating transit-amplifying cells in the crypt exchanged CK18 for CK20 above the mouth of the crypt and after moving to the villi; however, CK18-positive M cells in the crypt continued their expression of CK18 during movement to the FAE region. Terminal deoxynucleotidyl-transferase-mediated deoxyuridine-triphosphate-biotin nick-end labeling-positive apoptotic cells were specifically detected at the apical region of villi and FAE in the jejunum and ileum, and all were also stained for CK20. These data indicate that CK18 may be a molecular marker for bovine M cells in FAE and that M cells may transdifferentiate to CK20-positive enterocytes and die by apoptosis in the apex of the FAE.     

In vivo kinematics of two-component total ankle arthroplasty during non-weightbearing and weightbearing dorsiflexion/plantarflexion

Relatively high rates of loosening and implant failure have been reported after total ankle arthroplasty, especially in first and second generation implants. Abnormal kinematics and incongruency of the articular surface may cause increased loads applied to the implant with concomitant polyethylene wear, resulting in loosening and implant failure. The purpose of this study was to measure three-dimensional kinematics of two-component total ankle arthroplasty during non-weightbearing and weightbearing activities, and to investigate incongruency of the articular surfaces during these activities. Forty-seven patients with a mean age of 71 years were enrolled. Radiographs were taken at non-weightbearing maximal dorsiflexion and plantarflexion, and weightbearing maximal dorsiflexion, plantarflexion, and neutral position. 3D-2D model-image registration was performed using the radiographs and the three-dimensional implant models, and three-dimensional joint angles were determined. The implanted ankles showed 18.1±8.6° (mean±standard deviation) of plantarflexion, 0.1±0.7° of inversion, 1.2±2.0° of internal rotation, and 0.8±0.6mm of posterior translation of the talar component in the non-weightbearing activity, and 17.8±7.5° of plantarflexion, 0.4±0.5° of inversion, 1.8±2.0° of internal rotation, and 0.7±0.5mm of posterior translation in the weightbearing activity. There were no significant differences between the non-weightbearing and weightbearing kinematics except for the plantarflexion angle. Incongruency of the articular surface occurred in more than 75% of the ankles. Our observations will provide useful data against which kinematics of other implant designs, such as three-component total ankle arthroplasty, can be compared.     

CD157 Marks Tissue-Resident Endothelial Stem Cells with Homeostatic and Regenerative Properties

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Characteristic glycopeptides associated with extreme human longevity identified through plasma glycoproteomics

Background

Glycosylation is highly susceptible to changes of the physiological conditions, and accordingly, is a potential biomarker associated with several diseases and/or longevity. Semi-supercentenarians (SSCs; older than 105?years) are thought to be a model of human longevity. Thus, we performed glycoproteomics using plasma samples of SSCs, and identified proteins and conjugated N-glycans that are characteristic of extreme human longevity.

Skewed male reproductive success and pollen transfer in a small fragmented population of the heterodichogamous tree <Emphasis Type="Italic">Machilus thunbergii</Emphasis>

Heterodichogamy is defined as the presence of two flower morphs that exhibit the male and female functions at different times among individuals within a population. Heterodichogamy is regarded as an adaptation to promote outcrossing through enhanced inter-morph mating, together with a 1:1 morph ratio. However, in highly fragmented populations, the morph ratio may be more likely to be biased by stochastic events. In such a situation, individuals of a minority morph within a population are expected to have higher reproductive success than those of a majority morph, which may suffer from pollen shortages of the minority morph. In this paper, we evaluated mating patterns and male reproductive success in a highly fragmented population of Machilus thunbergii, a putative heterodichogamous evergreen laurel tree. Results of paternity analysis indicated that the selfing rate was not clearly different between the two morphs. In contrast, the proportion of intra-morph mating was higher in the majority-morph (MM) mother trees than in the minority-morph (MF) mother trees. Bayesian estimated male reproductive success indicated that male reproductive success was higher in minority-morph (MF) than in majority-morph (MM) mother trees. These findings indicate that (1) the majority morph mothers, suffering a shortage of the opposite morph pollen, could partly compensate for the reduced reproductive success by intra-morph mating rather than by selfing, and (2) negative-frequency dependent selection may be involved in the maintenance of the two morphs.     

Variation of clutch size and trophic egg proportion in a ladybird with and without male-killing bacterial infection

Maternally inherited bacterial endosymbionts can kill male embryos of their arthropod hosts to enhance the transmission efficiency of the endosymbionts. The resources from killed male eggs can be reallocated to infected female hatchlings as additional maternal investment. As a result, the number of offspring per patch and the maternal investment per offspring are expected to differ from the original optimal values for the host mother. Thus, in response to infection, these trait values should be adjusted to maximize the lifetime reproductive success of host females and the fitness of inherited endosymbionts as well. Here, we examined clutch size, egg size, and the proportion of trophic eggs (i.e., production of unhatched eggs, a maternal phenotype) per clutch of host mothers infected with male-killing bacteria. First, we developed a mathematical model to predict the optimal clutch size and trophic egg proportion in uninfected and infected females. Next, we experimentally compared these life-history traits in a ladybird, Harmonia yedoensis, between females infected or uninfected with male-killing Spiroplasma bacteria. Consistent with our predictions, clutch size was larger, egg size was smaller, and trophic egg proportion was lower in infected H. yedoensis females, compared with uninfected females. To our knowledge, this is the first empirical demonstration of variation in these life-history traits depending on infection with bacterial endosymbionts.     

Phosphorylation‐dependent Akt–Inversin interaction at the basal body of primary cilia

A primary cilium is a microtubule‐based sensory organelle that plays an important role in human development and disease. However, regulation of Akt in cilia and its role in ciliary development has not been demonstrated. Using yeast two‐hybrid screening, we demonstrate that Inversin (INVS) interacts with Akt. Mutation in the INVS gene causes nephronophthisis type II (NPHP2), an autosomal recessive chronic tubulointerstitial nephropathy. Co‐immunoprecipitation assays show that Akt interacts with INVS via the C‐terminus. In vitro kinase assays demonstrate that Akt phosphorylates INVS at amino acids 864–866 that are required not only for Akt interaction, but also for INVS dimerization. Co‐localization of INVS and phosphorylated form of Akt at the basal body is augmented by PDGF‐AA. Akt‐null MEF cells as well as siRNA‐mediated inhibition of Akt attenuated ciliary growth, which was reversed by Akt reintroduction. Mutant phosphodead‐ or NPHP2‐related truncated INVS, which lack Akt phosphorylation sites, suppress cell growth and exhibit distorted lumen formation and misalignment of spindle axis during cell division. Further studies will be required for elucidating functional interactions of Akt–INVS at the primary cilia for identifying the molecular mechanisms underlying NPHP2.