Periosteum stimulates subchondral bone densification in autologous chondrocyte transplantation in a sheep model

In this sheep study, we have tested the hypothesis that an osteogenic response is triggered in the subchondral bone by periosteum implanted in full thickness cartilage defects and can be prevented by replacing the periosteum by a cell-free collagen type I/III membrane. Two 7-mm diameter osteochondral defects were made in the trochlea groove and in the medial femoral condyle of one of the knees in each of 15 adult sheep. The animals were divided into three groups (n=5): a control group with untreated cartilage defects, a group treated with autologous chondrocyte transplantation (ACT) and periosteum, and a group treated with ACT in combination with a collagen I/III membrane cover. Histological examination was performed 1 year later. The optical density of the subchondral bone in the histological sections was measured with digital imaging software. There was a dramatic, statistically significant (P<0.0001; power=1) increase in bone density of 45%–70% under defects that were treated with the periosteal cover, compared with the collagen membrane and control groups, which displayed the same bone density. There was no difference in the cartilaginous reparative tissue in the defects in the three groups. Periosteum thus stimulates the remodelling process in subchondral bone. Stiffening of the subchondral bone can lead to degeneration of the overlying reparative cartilaginous tissue because of an increase in the mechanical stress in the tissue. These findings warrant evaluation of subchondral bone changes in patients treated by ACT and the correlation of these changes with clinical outcome.     

Ubiquitin and protein turnover in synapse function

Enduring modification of synapses is central to long-lasting neural circuit plasticity. Such adaptations include rapid posttranslational modification of existing synaptic proteins over periods of minutes and persisting changes in the abundance of synaptic proteins over hours to days. Recently, ubiquitination and protein degradation have emerged as additional mechanisms for modifying the function and molecular composition of synapses. These recent findings raise intriguing questions as to how enduring changes at synapses are accomplished in the face of robust, ongoing molecular turnover.     

The IL-27 receptor chain WSX-1 differentially regulates antibacterial immunity and survival during experimental tuberculosis

IL-12 is a potent inducer of IFN-gamma production and promotes a protective cell-mediated immune response after Mycobacterium tuberculosis infection. Recently, the IL-12-related cytokine IL-27 was discovered, and WSX-1 was identified as one component of the IL-27R complex. To determine the functional significance of IL-27/WSX-1 during tuberculosis, we analyzed the course of infection and the immune response in WSX-1-KO mice after aerosol infection with M. tuberculosis. In the absence of WSX-1, an increased production of the proinflammatory cytokines TNF and IL-12p40 resulted in elevated CD4+ T cell activation and IFN-gamma production, which enhanced macrophage effector functions and reduced bacterial loads. This is the first occasion of a selectively gene-deficient mouse strain showing higher levels of protective immunity against M. tuberculosis infection than wild-type mice. However, a concomitantly increased chronic inflammatory response also accelerated death of infected WSX-1-KO mice. In vitro, IL-27 induced STAT3 phosphorylation and inhibited TNF and IL-12 production in activated peritoneal macrophages, indicating a novel feedback mechanism by which IL-27 can modulate excessive inflammation. In conclusion, IL-27 both prevents optimal antimycobacterial protection and limits the pathological sequelae of chronic inflammation.     

Mass production of entomopathogenic nematodes for plant protection

Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are commercially used to control pest insects. They are symbiotically associated with bacteria of the genera Photorhabdus and Xenorhabdus, respectively, which are the major food source for the nematodes. The biology of the nematode-bacterium complex is described, a historical review of the development of in vitro cultivation techniques is given and the current use in agriculture is summarised. Cultures of the complex are pre-incubated with the symbiotic bacteria before the nematodes are inoculated. Whereas the inoculum preparation and preservation of bacterial stocks follow standard rules, nematodes need special treatment. Media development is mainly directed towards cost reduction, as the bacteria are able to metabolise a variety of protein sources to provide optimal conditions for nematode reproduction. The process technology is described, discussing the influence of bioreactor design and process parameters required to obtain high nematode yields. As two organisms are grown in one vessel and one of them is a multicellular organism, the population dynamics and symbiotic interactions need to be understood in order to improve process management. Major problems can originate from the delayed or slow development of the nematode inoculum and from phase variants of the symbiotic bacteria that have negative effects on nematode development and reproduction. Recent scientific progress has helped to understand the biological and technical parameters that influence the process, thus enabling transfer to an industrial scale. As a consequence, costs for nematode-based products could be significantly reduced.     

Inflammation and lymphocyte activation during mycobacterial infection in the interferon-gamma-deficient mouse

Interferon-gamma is a pivotal cytokine in the protective response to tuberculosis. In its absence rampant bacterial growth results in tissue destruction and death. While macrophage activation is key, this pleiotropic cytokine has other secondary but significant roles. To investigate these roles, both intravenous and aerosol infection of the IFN-gamma gene disrupted (GKO) mouse was performed. For the first time we describe the very similar growth of bacteria, during the initial phase of infection, between control and GKO mice. During this initial phase, however, very different histopathologic consequences between control and GKO mice were observed. Key observations included an early increased accumulation of granulocytes and a much more rapid and pronounced interstitial pneumonia in the GKO mice. As infection developed, GKO mice mounted an antigen-specific response; however, lymphocyte activation was much more rapid in these mice. Of interest is the fact that this increased rapidity occurred prior to significant differences in bacterial number. Taken together these data support a role for IFN-gamma in limiting both initial cellular recruitment and acquired lymphocytic responses to mycobacterial infection. This role may be key in surviving the kind of chronic stimulatory disease caused by Mycobacterium tuberculosis.     

广东顺德生态乐园夏季鸟类资源和保护

报道了顺德生态乐园夏季鸟类资源的调查 ,记录了该乐园鸟类有 55种 ,隶属 6目2 0科 ,其中属国家二级重点保护鸟类 9种。对鸟类的生态作用、种类和组成作了讨论 ,并提出了保护鸟类的重要性和保护措施。     

Local evolution of obligate autogamy inEpipactis helleborine subsp.neerlandica (Orchidaceae)

Isozyme analysis was used to assess the origin of the DanishEpipactis renzii, a local endemic of open coastal dunes. It seems to have evolved recently in several local populations of the more or less allogamousE. helleborine subsp.neerlandica. The obligately autogamousE. renzii is restricted to the easternmost part of the Danish range ofE. helleborine subsp.neerlandica, indicating that transition to obligate autogamy has been a selective advantage in that area. This may be explained by water stress, caused by a higher evapotranspiration (cf. the mean temperature of July which increases towards the east) — obligate autogamy shortens the time span from anthesis to fruit set due to a rapid pollination process. We propose thatE. renzii should only be recognized as a variety ofE. helleborine subsp.neerlandica.     

Sustainable control of black vine weevil larvae,Otiorhynchus sulcatus (Coleoptera: Curculionidae) with Heterorhabditis bacteriophora in strawberry

Efficacy, persistence and recovery of the nematode Heterorhabditis bacteriophora was tested in the laboratory after application of the nematode to strawberry roots by dipping. To mitigate nematode sedimentation and improve attachment to strawberry roots, carboxy-methyl-cellulose was added to the nematode solution. Mortality of black vine weevil Otiorhynchus sulcatus varied between 90 and 96% in the pot trials.