Halarachnion (Furcellariaceae,Rhodophyta), a newly reported genus for the Gulf of Mexico,with the description of Halarachnion louisianensis sp. nov

Halarachnion is a newly reported genus for the Gulf of Mexico where it is represented by an undescribed species growing attached to rhodoliths at 52–73 m depth offshore Louisiana in the northwestern Gulf, USA. Aspects of the vegetative and female reproductive morphology of the Gulf species are documented, and compared to of Halarachnion latissimun from Japan. Halarachnion louisianensis sp. nov. is a monoecious, presumably heteromorphic species as inferred from the absence of tetrasporophytic specimens in our collections. Halarachnion latissimum, in contrast, is a dioecious species that is isomorphic. A distinct reproductive character that differentiates both species is the behavior of a connecting filament of which a lateral process fuses with an auxiliary cell lobe and effects more than one diploidization in H. louisianensis versus directly fusing with an auxiliary cell and effecting only a single diploidization in H. latissimum. Comparative chloroplast‐encoded rbcL sequence analysis indicates that the closest species relationship of isolates from the Gulf of Mexico remains equivocal, whereas reproductive morphology points to a closer affinity with H. ligulatum. This is the first report of the Furcellariaceae, a family in the Solieriaceae‐complex, for the Gulf of Mexico.     

Observations of the migration of adult Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) from belowground to the soil surface and their reproductive status by MRI

Field observations indicate that white grub beetles Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scarabaeidae) pupate approximately 40 cm underground and then emerge from the soil surface as adults. Although the factors influencing adult emergence from the soil have been studied, the migration of adults from belowground to the surface has never been characterized. In this study, the vertical movement of virgin adults from natural eclosion depths to their emergence from the soil surface was investigated. Virgin adults were introduced at a depth of 40 cm from the soil surface in wooden-framed glass cases, and the vertical position of each individual was checked every day. Both females and males emerged near the soil surface at approximately day 50 after they were transferred from 24 °C to 18 °C conditions. The maturity of the ovaries in unemerged and emerged females was also observed by magnetic resonance imaging. All females that had emerged from the soil possessed developed oocytes, and most possessed mature eggs. The cross-sectional area of eggs was determined in magnetic resonance images and compared between unemerged and emerged females, and the egg areas of emerged females were significantly larger than those of unemerged females. Our results indicate that the timing of female emergence from soil corresponded to ovary maturity in this species.     

Accumulation of macrophages expressing MRP8 and MRP14 in skin lesions during Leishmania major infection in BALB/c and RAG-2 knockout mice

Migration inhibitory factor-related protein 8 (MRP8) and MRP14 are expressed by myeloid cells and especially known as marker proteins of an immature and inflammatory subtype of macrophages. In this study, we immunohistochemically examined an accumulation of MRP8+ and MRP14+ macrophages in skin lesions during Leishmania major infection in susceptible BALB/c and RAG-2-/- mice. L. major infection caused the development of a nodular type of skin lesion at the infection site in mice and a massive accumulation of macrophages was observed in the lesions at four weeks after the infection. Immunohistochemical analyses showed MRP8+ and MRP14+ macrophages are predominant cell types in the skin lesions in both mouse strains. In contrast, F4/80+ cells, which correspond to mature macrophages, were rarely found in the skin lesions. These data suggest that the accumulation of inflammatory subtype of macrophages in BALB/c mice during L. major infection can be induced without acquired immune responses.     

Increasing dihydrobiopterin causes dysfunction of endothelial nitric oxide synthase in rats in vivo

An elevation of oxidized forms of tetrahydrobiopterin (BH(4)), especially dihydrobiopterin (BH(2)), has been reported in the setting of oxidative stress, such as arteriosclerotic/atherosclerotic disorders, where endothelial nitric oxide synthase (eNOS) is dysfunctional, but the role of BH(2) in the regulation of eNOS activity in vivo remains to be evaluated. This study was designed to clarify whether increasing BH(2) concentration causes endothelial dysfunction in rats. To increase vascular BH(2) levels, the BH(2) precursor sepiapterin (SEP) was intravenously given after the administration of the specific dihydrofolate reductase inhibitor methotrexate (MTX) to block intracellular conversion of BH(2) to BH(4). MTX/SEP treatment did not significantly affect aortic BH(4) levels compared with control treatment. However, MTX/SEP treatment markedly augmented aortic BH(2) levels (291.1 ± 29.2 vs. 33.4 ± 6.4 pmol/g, P < 0.01) in association with moderate hypertension. Treatment with MTX alone did not significantly alter blood pressure or BH(4) levels but decreased the BH(4)-to-BH(2) ratio. Treatment with MTX/SEP, but not with MTX alone, impaired ACh-induced vasodilator and depressor responses compared with the control treatment (both P < 0.05) and also aggravated ACh-induced endothelium-dependent relaxations (P < 0.05) of isolated aortas without affecting sodium nitroprusside-induced endothelium-independent relaxations. Importantly, MTX/SEP treatment significantly enhanced aortic superoxide production, which was diminished by NOS inhibitor treatment, and the impaired ACh-induced relaxations were reversed with SOD (P < 0.05), suggesting the involvement of eNOS uncoupling. These results indicate, for the first time, that increasing BH(2) causes eNOS dysfunction in vivo even in the absence of BH(4) deficiency, demonstrating a novel insight into the regulation of endothelial function.     

UV radiation reduces epidermal cell expansion in Arabidopsis thaliana leaves without altering cellular microtubule organization

Upon chronic UV treatment pavement cell expansion in Arabidopsis leaves is reduced, implying alterations in symplastic and apoplastic properties of the epidermal cells. In this study, the effect of UV radiation on microtubule patterning is analysed, as microtubules are thought to serve as guiding rails for the cellulose synthase complexes depositing cellulose microfibrils. Together with hemicelluloses, these microfibrils are regarded as the load-bearing components of the cell wall. Leaves of transgenic plants with fluorescently tagged microtubules (GFP-TUA6) were as responsive to UV as wild type plants. Despite the UV-induced reduction in cell elongation, confocal microscopy revealed that cellular microtubule arrangements were seemingly not affected by the UV treatments. This indicates an unaltered deposition of cellulose microfibrils in the presence of UV radiation. Therefore, we surmise that the reduction in cell expansion in UV-treated leaves is most probably due to changes in cell wall loosening and/or turgor pressure.Key words: arabidopsis, cell expansion, GFP-TUA6, leaf development, microtubule cytoskeleton, UV radiationPhotosynthetic functions such as solar light capture and carbon fixation are highly evolved features of plant leaves. To fulfil these functions in an optimal way, leaf development needs to be tuned to environmental conditions. Leaves are continuously exposed and subjected to environmental influences, which serve as co-regulators of leaf and plant development.¹ This ability of plants to adapt, secures the plant''s survival, even under non-optimal conditions. An example of a regulatory environmental parameter is solar light, indispensable for photosynthesis but potentially causing photoinhibition and/or UV-radiation stress. The highly energetic ultraviolet B (UV-B) rays of short wavelengths (280–315 nm) can both cause damage, as well as induce a range of specific metabolic and morphogenic plant responses. It was reported before that exposure to low dose UV radiation reduces Arabidopsis leaf size due to a decreased cell size.² Expansion of leaf epidermal cells of Arabidopsis thaliana is the combined action of promotion and restriction of growth, resulting in the typical irregular sinuous pavement cells. It has been postulated that cellulose microfibrils are responsible for generating a force opposing isotropic expansion by creating neck regions in between outgrowing lobes.³ As the microtubule cytoskeleton is believed to serve as guiding rails for the cellulose synthase complexes (CESAs),⁴ the deposition of the cellulose fibrils is intimately linked to the cortical microtubule arrangement. We have studied the UV-effect on microtubule organisation in leaf epidermal cells whose expansion had decreased upon this UV radiation. Microtubules in the adaxial pavement cells of the fourth leaf were monitored on several successive days in a transgenic line containing GFP fused to tubulin A6.⁵ The chronic UV treatment was started on day 0 when the plants were 2 weeks old, using UV exposure conditions as described in reference ². First the responsiveness of the GFP-TUA6 plants to UV radiation was evaluated. Similar to wild type (WT) plants,² the GFP-TUA6 plants had smaller leaves following 8 days of UV treatment (t-test, p < 0.01) (Fig. 1). This was caused by a significant reduction in the generalized cell area average of all measured cells, irrespective of the location within the leaf (Fig. 1; t-test, p < 0.01). In more detail, the average cell area within the base, middle and top zones of the GFP-TUA6 leaf was systematically lower in UV-treated leaves from 8 days after the treatment started onwards (data not shown).Open in a separate windowFigure 1Effect of UV radiation on leaf and cell area after different days of UV radiation. Open asterisks indicate a statistically significant difference in leaf area between UV-treated and control plants, black asterisks indicate statistically significant difference in cell area (t-test, *p < 0.05, **p < 0.01, ***p < 0.001). Error bars indicate the standard error for five different leaves at all measured time-points and 600, 170 and 180 cells at day 0, 8 and 12 respectively.As GFP-TUA6 leaves were as responsive to UV radiation as wild type leaves, confocal microscopy was used to visualize the organisation of the cortical microtubules facing the outer periclinal wall of the adaxial epidermis. No clear difference in microtubule (re)organization could be detected during the development of pavement cells, and throughout the UV treatment period. As shown in Figure 2 at day 2, pavement cells with comparable areas are similarly shaped in control and UV-irradiated plants and contain similar microtubule arrangements (Fig. 2 and marked cells). This means that microtubule organization is not directly affected by the UV exposure and that shape development proceeds in an analoguous manner as under control conditions. This lack of alteration in the microtubule arrangement can be observed for cells at the leaf tip, which were already in the process of lobe formation at the start of the exposure period, as well as for cells at the leaf base. Under our growth conditions, and in the monitored leaf number 4, cell proliferation still took place in this part of the leaf and lobes only started to appear on the cell surface. As microtubules are linked to the deposition of cellulose microfibrils, it can be assumed that no alterations in cellulose deposition occur upon UV treatment either. We can therefore conclude that the process of lobe formation and microtubule patterning is not impeded and that only the extent of cell expansion is restricted upon UV exposure.Open in a separate windowFigure 2Microtubule pattern in control and UV-exposed leaves visualized using GFP-TUA6 and confocal microscopy. Both images are from cells at the mid zone of the fourth leaf at day 2. Microtubules are similarly arranged in equally shaped and sized cells of control and UV-exposed leaves. The marked cells show a pattern whereby the tubules are centred in the neck regions between two outgrowing lobes.According to the Lockhart equation,⁶ cell (wall) growth is modulated by wall biomechanics and turgor pressure. Concerning turgor pressure, no clear differences in this factor between UV-exposed and control plants of Lactuca sativa L.⁷ and Pisum sativum⁸ could be observed, reinforcing the idea that especially the modulation of cell wall properties is the main factor causing the observed UV-induced reduction in cell expansion. Some reports indicate differential expression of wall loosening enzymes like expansins or xyloglucan endotransglycosylase/hydrolases (XTHs),^9,10 or cell wall strengthening enzymes as particular peroxidases⁷ after UV exposure. Another key event could involve UV-mediated changes in the phenylpropanoid pathway, which may cause changes in the lignin biosynthesis. As shown by the literature^11–14 lignin may well be an important modulator of cell wall architecture in Arabidopsis and therefore alterations in lignin synthesis could form the basis for morphological modifications. Further research on the cell wall properties of UV-treated plants may resolve this uncertainty.As a general conclusion we can state that the patterning of microtubules is not altered, but that alterations in cell wall composition or arrangements are the most plausible candidates for the observed reduction in pavement cell expansion upon chronic UV treatment.     

A novel DC therapy with manipulation of MKK6 gene on nickel allergy in mice

BACKGROUND: Although the activation of dermal dendritic cells (DCs) or Langerhans cells (LCs) via p38 mitogen-activated protein kinase (MAPK) plays a crucial role in the pathogenesis of metal allergy, the in vivo molecular mechanisms have not been identified and a possible therapeutic strategy using the control of dermal DCs or LCs has not been established. In this study, we focused on dermal DCs to define the in vivo mechanisms of metal allergy pathogenesis in a mouse nickel (Ni) allergy model. The effects of DC therapy on Ni allergic responses were also investigated. METHODS AND FINDING: The activation of dermal DCs via p38 MAPK triggered a T cell-mediated allergic immune response in this model. In the MAPK signaling cascade in DCs, Ni potently phosphorylated MAP kinase kinase 6 (MKK6) following increased DC activation. Ni-stimulated DCs could prime T cell activation to induce Ni allergy. Interestingly, when MKK6 gene-transfected DCs were transferred into the model mice, a more pronounced allergic reaction was observed. In addition, injection of short interfering (si) RNA targeting the MKK6 gene protected against a hypersensitivity reaction after Ni immunization. The cooperative action between T cell activation and MKK6-mediated DC activation by Ni played an important role in the development of Ni allergy. CONCLUSIONS: DC activation by Ni played an important role in the development of Ni allergy. Manipulating the MKK6 gene in DCs may be a good therapeutic strategy for dermal Ni allergy.     

Habitat differentiation in the early life stages of simultaneously mass-spawning corals

The settlement process of coral larvae following simultaneous mass-spawning remains poorly understood, particularly in terms of population and community parameters. Here, the larval settlement patterns of Acropora corals, which are the most diverse genera of scleractinian corals at the species (haplotype) level, were investigated within a single subtropical reef. Across a 4-year period (2007–2010), the mitochondrial and nuclear molecular markers of 1,073 larval settlers were analyzed. Of the 11 dominant haplotypes of recruited populations, nine exhibited non-random patterns of settlement distribution. This result suggests that the actual habitat segregation starts during the early swimming larval stages of their life history, rather than by natural selection after random settlement. In addition, the presence of a depth-related settlement pattern supports that species-specific vertical zonation of coral larvae may play a role in the establishment of habitat segregation. Moreover, in some species that showed a preference toward the shoreward area of the bay, the settlement pattern was consistent with that of the adult distribution. This result indicates that the gametes were not mixed between fore and back reefs in the period from fertilization to settlement during the mass-spawning event, even within a single small reef. Another compatible hypothesis of this pattern is that the larvae are able to recognize various types of environmental information, facilitating the selection of optimal micro-habitats. Overall, Acropora coral larvae that are produced from a simultaneous mass-spawning event may have adapted to complex reef topography by means of multi-step habitat selection at settlement, corresponding to different spatial scales.     

Male mate searching behavior in the black chafer Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae): response to pheromone lures of various colors and intensities

In order to understand the visual orientation mechanisms of the male black chafer Holotrichia loochooana loochooana to females, we examined male behavioral response to colored objects (lures) when female sex pheromone was present. In the field, males landed more frequently on darker lures than on lighter ones of the same color. Among lures of different colors but with the same brightness, males preferred landing on black, blue, or red ones to green or grey ones. The reflectance intensities of preferred lures were weaker than those of green and grey in the range of 540–580 nm. This range is considered to affect choice by males. When females perch on the leaf edges of the food plant to adopt a calling posture, the dominant background color is that of the leaves (i.e., green). This means that the landing target forms a silhouette (dark spot) which is prominent against a background of green leaves, providing maximum visual acuity for mating.     

Biology and interactions of two distinct monopartite begomoviruses and betasatellites associated with radish leaf curl disease in India

Background

Emerging whitefly transmitted begomoviruses are major pathogens of vegetable and fibre crops throughout the world, particularly in tropical and sub-tropical regions. Mutation, pseudorecombination and recombination are driving forces for the emergence and evolution of new crop-infecting begomoviruses. Leaf curl disease of field grown radish plants was noticed in Varanasi and Pataudi region of northern India. We have identified and characterized two distinct monopartite begomoviruses and associated beta satellite DNA causing leaf curl disease of radish (Raphanus sativus) in India.

Results

We demonstrate that RaLCD is caused by a complex of two Old World begomoviruses and their associated betasatellites. Radish leaf curl virus-Varanasi is identified as a new recombinant species, Radish leaf curl virus (RaLCV) sharing maximum nucleotide identity of 87.7% with Tomato leaf curl Bangladesh virus-[Bangladesh:2] (Accession number AF188481) while the virus causing radish leaf curl disease-Pataudi is an isolate of Croton yellow vein mosaic virus-[India] (CYVMV-IN) (Accession number AJ507777) sharing 95.8% nucleotide identity. Further, RDP analysis revealed that the RaLCV has a hybrid genome, a putative recombinant between Euphorbia leaf curl virus and Papaya leaf curl virus. Cloned DNA of either RaLCV or CYVMV induced mild leaf curl symptoms in radish plants. However, when these clones (RaLCV or CYVMV) were individually co-inoculated with their associated cloned DNA betasatellite, symptom severity and viral DNA levels were increased in radish plants and induced typical RaLCD symptoms. To further extend these studies, we carried out an investigation of the interaction of these radish-infecting begomoviruses and their associated satellite, with two tomato infecting begomoviruses (Tomato leaf curl Gujarat virus and Tomato leaf curl New Delhi virus). Both of the tomato-infecting begomoviruses showed a contrasting and differential interaction with DNA satellites, not only in the capacity to interact with these molecules but also in the modulation of symptom phenotypes by the satellites.

Conclusion

This is the first report and experimental demonstration of Koch's postulate for begomoviruses associated with radish leaf curl disease. Further observations also provide direct evidence of lateral movement of weed infecting begomovirus in the cultivated crops and the present study also suggests that the exchange of betasatellites with other begomoviruses would create a new disease complex posing a serious threat to crop production.     

Role of epithelial-stem cell interactions during dental cell differentiation

Epithelial-mesenchymal interactions regulate the growth and morphogenesis of ectodermal organs such as teeth. Dental pulp stem cells (DPSCs) are a part of dental mesenchyme, derived from the cranial neural crest, and differentiate into dentin forming odontoblasts. However, the interactions between DPSCs and epithelium have not been clearly elucidated. In this study, we established a mouse dental pulp stem cell line (SP) comprised of enriched side population cells that displayed a multipotent capacity to differentiate into odontogenic, osteogenic, adipogenic, and neurogenic cells. We also analyzed the interactions between SP cells and cells from the rat dental epithelial SF2 line. When cultured with SF2 cells, SP cells differentiated into odontoblasts that expressed dentin sialophosphoprotein. This differentiation was regulated by BMP2 and BMP4, and inhibited by the BMP antagonist Noggin. We also found that mouse iPS cells cultured with mitomycin C-treated SF2-24 cells displayed an epithelial cell-like morphology. Those cells expressed the epithelial cell markers p63 and cytokeratin-14, and the ameloblast markers ameloblastin and enamelin, whereas they did not express the endodermal cell marker Gata6 or mesodermal cell marker brachyury. This is the first report of differentiation of iPS cells into ameloblasts via interactions with dental epithelium. Co-culturing with dental epithelial cells appears to induce stem cell differentiation that favors an odontogenic cell fate, which may be a useful approach for tooth bioengineering strategies.