Silvorchis vietnamica (Orchidaceae,Orchidoideae, Vietorchidinae), a new miniature mycotrophic species from southern Vietnam

A second species of Silvorchis, until now considered to be a presumably extinct monotypic genus endemic to western Java has been discovered in southern Vietnam. The species, here named as S. vietnamica, is described and illustrated, with data on its distribution, ecology, phenology and estimated conservation status. A key for identification of the two known species of the genus is also provided. The taxonomic affinities and phylogenetic placement of the newly discovered plant are briefly discussed.     

Three-dimensional endothelial-tumor epithelial cell interactions in human cervical cancers

Summary The purpose of this study is to understand the multicellular interaction between tumor epithelial (TEC) and human umbilical vein endothelial cells (HUVEC). The development of in vitro systems in which to coculture these cells as multicellular aggregates is very critical. Cell lines were established from cervical tumor cells (n=6) and two from HUVEC (n=2) and they were cultured as three-dimensional (3-D) multicellular-cultures using Cytodex-3 microcarrier beads in the rotating wall vessel (RWV). After a 240-h incubation, TEC and HUVEC proliferated exponentially to 4.2×10⁷ and 2.2 × 10⁷ cells/ml, respectively, without requiring a feeder layer; in contrast to the two-dimensional (2-D) cultures that average about 8 × 10⁶ cells/ml. Phase contrast microscopy indicated formation of 3-D aggregates that varied in size from 0.5 to 5 mm. The size of the aggregates (1–5 mm, 6⊋ash;14 microcarriers) increased over time; however, the number of aggregates (0.5–1 mm, 2–5 microcarriers) decreased over a long-term incubation (240 h) because the cells merged to form large clumps. Maximum aggregation was observed with TEC at 120 h and HUVEC at 96 h. The culture of TEC in the absence of HUVEC produced minimal differentiation in contrast to cocultures. The TEC and HUVEC as cocultures in RWV proliferated at an accelerated rate (1.3 × 10⁷ cells/ml, 96 h). The TEC-HUVEC coculture presented tubular structures penetrating the tumor cell masses, forming aggregates larger in size than the monocultures and typically with greater cell mass and number. The cells were viable (trypan blue exclusion) and metabolically active (glucose utilization) until 240 h. These data suggest that RWV provides a new model that allows us to investigate the regulatory factors that govern tumor angiogenesis.     

Tracking mesenchymal stromal cells using an ultra‐bright TAT‐functionalized plasmonic‐active nanoplatform

High‐resolution tracking of stem cells remains a challenging task. An ultra‐bright contrast agent with extended intracellular retention is suitable for in vivo high‐resolution tracking of stem cells following the implantation. Here, a plasmonic‐active nanoplatform was developed for tracking mesenchymal stromal cells (MSCs) in mice. The nanoplatform consisted of TAT peptide‐functionalized gold nanostars (TAT‐GNS) that emit ultra‐bright two‐photon photoluminescence capable of tracking MSCs under high‐resolution optical imaging. In vitro experiment showed TAT‐GNS‐labeled MSCs retained a similar differentiability to that of non‐labeled MSCs controls. Due to their star shape, TAT‐GNS exhibited greater intracellular retention than that of commercial Q‐Tracker. In vivo imaging of TAT‐GNS‐labeled MSCs five days following intra‐arterial injections in mice kidneys showed possible MSCs implantation in juxta‐glomerular (JG) regions, but non‐specifically in glomeruli and afferent arterioles as well. With future design to optimize GNS labeling specificity and clearance, plasmonic‐active nanoplatforms may be a useful intracellular tracking tool for stem cell research.

An ultra‐bright intracellular contrast agent is developed using TAT peptide‐functionalized gold nanostars (TAT‐GNS). It poses minimal influence on the stem cell differentiability. It exhibits stronger two‐photon photoluminescence and superior labeling efficiency than commercial Q‐Tracker. Following renal implantation, some TAT‐GNS‐labeled MSCs permeate blood vessels and migrate to the juxta‐glomerular region.     

Class IgG,IgM and IgA antibodies againstStaphylococcus aureus antigens in human serum and saliva

Using the ELISA method antibodies against the sonicate, teichoic acid (TA) and exoproducts ofStaphylococcus aureus were determined in sera and saliva of healthy individuals. Main serum antibodies against all the antigens used were shown to be class IgG antibodies. However, antigens of the sonicate stimulated significantly even the systemic IgA response. In the saliva class IgA antibodies predominated, but IgG antibody levels against TA and exoproducts approached the level of IgA antibodies. Levels of IgM antibodies against all antigens tested were low in both the serum and saliva which corresponds with the anamnestic type of response. On the basis of these results one may assume that not only IgG, but also IgA antibodies are important in the systemic immunity against staphylococcal infection and in the immunity of mucous membranes; besides IgA, even class IgG antibodies play an important role.     

Influence of humidity and water availability on the survival ofAmblyseius idaeus andA. anonymus (Acarina: Phytoseiidae)

Amblyseius idaeus (Denmark & Muma) andA. anonymus Chant & Baker are morphologically very similar species of phytoseiids inhabiting areas in South America that have very different levels of humidity. Above 60% RH, nearly all eggs of both species hatch successfully, but below 60% RH the egg hatching rate ofA. anonymus is very poor, whereas eggs ofA. idaeus hatch at humidities as low as 30% RH. The mobile stages ofA. idaeus are better able to survive in absence of food and water than those ofA. anonymus. Water availability promotes survival of both species, but its effect onA. idaeus exceeds that onA. anonymus. These differences in low-humidity tolerance and survival ability are consistent with the climatic origin of these phytoseiid species;Amblyseius ideaus has been reported from very dry and humid areas, andA. anonymus from humid areas only.In comparison with other phytoseiid species, the eggs ofA. idaeus have the highest tolerance to low humidities reported to date, and, among the phytoseiids that are shown to be capable of controllingTetranychus spp., this tolerance appears to be exceptionally high. The impact of this result on the scope of biological control ofTetranychus spp. is discussed.     

Using Superfolder Green Fluorescent Protein for Periplasmic Protein Localization Studies

Studies investigating the subcellular localization of periplasmic proteins have been hampered by problems with the export of green fluorescent protein (GFP). Here we show that a superfolding variant of GFP (sfGFP) is fluorescent following Sec-mediated transport and works best when the cotranslational branch of the pathway is employed.     

The majority of CD4+8- thymocytes are functionally immature.

The thymus is the major site of T cell development and repertoire selection. During these processes, T cells segregate into two subsets that express either CD4 or CD8 accessory molecules, the phenotype of peripheral T cells. Analysis of CD4+8- thymocytes revealed that the majority of these cells express the heat-stable Ag (HSA) but not the nonclassical class I Ag, Qa-2. This HSA+, Qa-2- phenotype is similar to that of the less mature, CD4+8+ thymocytes. The remaining CD4+8- thymocytes possess the HSA-, Qa-2+ phenotype of peripheral T cells. To determine whether the Qa-2-, CD4+8- thymic subset is fully mature, we have analyzed the functional status of these CD4+8- subpopulations. The results indicate that only those thymocytes which express Qa-2 are fully responsive to anti-TCR stimulation in a manner analogous to peripheral T cells. The Qa-2- subset is nonresponsive to stimulation by anti-TCR antibodies that have been immobilized to plastic, even in the presence of lymphokines or syngeneic APC. This subset is, however, capable of proliferating to allogeneic cells or to anti-TCR on the surface of syngeneic APC, although not to the levels achieved by Qa-2+ thymocytes. Thus, the Qa-2- subset appears to require additional interactions which are not necessary for peripheral T cells or Qa-2+ thymocytes. Relevant to this issue, the Qa-2+ thymocyte subset does not appear until relatively late in development, and does not reach adult frequencies until several weeks after birth. These results would suggest that there is a progression from HSA+, Qa-2- to HSA-, Qa-2+ which parallels the maturation of functional responsiveness. These findings are important to understanding T cell selection since thymocytes with such a decreased responsiveness may have a differential capacity for tolerance induction. The results presented suggest that the bulk of CD4+8- thymocytes are not fully mature and that Qa-2 may serve as a marker for T cells with a more complete functional competence.