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Key message

Direct, non-invasive X-ray microtomography and optical technique observations applied in stems and leaves of intact seedlings revealed that laurel is highly resistant to drought-induced xylem embolism. Contrary to what has been brought forward, daily cycles of embolism formation and refilling are unlikely to occur in this species and to explain how it copes with drought.

Context

There has been considerable controversy regarding xylem embolism resistance for long-vesselled angiosperm species and particularly for the model species for refilling (Laurus nobilis L.).

Aims

The purpose of this study was to resolve the hydraulic properties of this species by documenting vulnerability curves of different organs in intact plants.

Methods

Here, we applied a direct, non-invasive method to visualize xylem embolism in stems and leaves of intact laurel seedlings up to 2-m tall using X-ray microtomography (microCT) observations and the optical vulnerability technique. These approaches were coupled with complementary centrifugation measurements performed on 1-m long branches sampled from adult trees and compared with additional microCT analyses carried out on 80-cm cut branches.

Results

Direct observations of embolism spread during desiccation of intact laurels revealed that 50% loss of xylem conductivity (Ψ50) was reached at ??7.9?±?0.5 and ??8.4?±?0.3 MPa in stems and leaves, respectively, while the minimum xylem water potentials measured in the field were ??4.2 MPa during a moderate drought season. Those findings reveal that embolism formation is not routine in Laurus nobilis contrary to what has been previously reported. These Ψ50 values were close to those based on the flow-centrifuge technique (??9.2?±?0.2 MPa), but at odds with microCT observations of cut branches (??4.0?±?0.5 MPa).

Conclusion

In summary, independent methods converge toward the same conclusion that laurel is highly resistant to xylem embolism regardless its development stage. Under typical growth conditions without extreme drought events, this species maintains positive hydraulic safety margin, while daily cycles of embolism formation and refilling are unlikely to occur in this species.
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Monocarboxylate transporters (MCTs) support tumour growth by regulating the transport of metabolites in the tumour microenvironment. High MCT1 or MCT4 expression is correlated with poor outcomes in human patients with head and neck squamous cell carcinoma (HNSCC). Recently, drugs targeting these transporters have been developed and may prove to be an effective treatment strategy for HNSCC. Feline oral squamous cell carcinoma (OSCC) is an aggressive and treatment‐resistant malignancy resembling advanced or recurrent HNSCC. The goals of this study were to investigate the effects of a previously characterized dual MCT1 and MCT4 inhibitor, MD‐1, in OSCC as a novel treatment approach for feline oral cancer. We also sought to determine the potential of feline OSCC as a large animal model for the further development of MCT inhibitors to treat human HNSCC. In vitro, MD‐1 reduced the viability of feline OSCC and human HNSCC cell lines, altered glycolytic and mitochondrial metabolism and synergized with platinum‐based chemotherapies. While MD‐1 treatment increased lactate concentrations in an HNSCC cell line, the inhibitor failed to alter lactate levels in feline OSCC cells, suggesting an MCT‐independent activity. In vivo, MD‐1 significantly inhibited tumour growth in a subcutaneous xenograft model and prolonged overall survival in an orthotopic model of feline OSCC. Our results show that MD‐1 may be an effective therapy for the treatment of feline oral cancer. Our findings also support the further investigation of feline OSCC as a large animal model to inform the development of MCT inhibitors and future clinical studies in human HNSCC.  相似文献   
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Understanding the interactions among biological and physical processes is essential to determining how the environment affects transport and survival of fishes. We examined vertical distribution in larval Atlantic menhaden (Brevoortia tyrannus) and Atlantic croaker (Micropogonias undulatus) using 126 depth stratified tows in Delaware Bay, USA, during two cruises, in December 2007 and February 2008. Menhaden larvae were 16.8–24.6 and 20.5–26.2 mm standard length in December and February. Corresponding lengths for croaker were 9.3–17.9 and 8.6–19.6 mm. Using empirical observations, and statistically derived models, we explored larval concentration for both species as a function of location, depth, diel period, tidal period, size, and pairwise interactions. Menhaden concentration was best modeled as a function of station, cruise, and interactions between depth and size as well as between station and cruise. No significant differences in larval menhaden concentration were present among tidal and diel periods. Croaker concentration was best modeled as a function of size and interactions between station and diel period, depth and size, cruise and size. Despite tidal period not emerging as a significant model parameter, we observed larger croaker larvae during nighttime flood tides. Our statistical models are consistent with processes of up‐estuary transport for both species, suggesting larvae are increasingly affected by behavioral responses as larvae grow, exhibiting stronger patterns in vertical distribution. The results refine our understanding of the potential importance of size‐related differences in vertical distribution for larval transport in these species. Future research should examine the interactions among size‐specific vertical migratory capabilities, vertical distribution, transport, and retention.  相似文献   
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Serradella (Ornithopus) species are high‐quality pasture legumes that originate from the Mediterranean basin and have been increasingly used in southern Australian temperate grazing systems. They are generally regarded as tolerant of soils with low pH and, by inference, elemental toxicities such as aluminium (Al). No studies have examined the effect of high Al concentrations on the growth of French serradella (Ornithopus sativus Brot.) or newly developed cultivars of yellow serradella (O. compressus L.). Several cultivars/accessions of each species were grown in low ionic‐strength nutrient solutions at pHCa 4.5 containing a range of Al concentrations. Their susceptibility to root growth inhibition by Al was benchmarked against reference species ranging from Al‐sensitive to Al‐tolerant. Most serradella cultivars had moderate‐to‐high Al tolerance in solution culture but one yellow and two French serradella cultivars ranked alongside the Al‐sensitive reference species. A subset of cultivars and reference species were then grown in an Al‐toxic soil to test the validity of the solution culture results; these cultivars spanned the apparent range in Al sensitivity/tolerance indicated by the solution culture experiment. Variation in the relative root length achieved in Al‐toxic solution culture explained ~59% of the variation in the relative root length achieved in the acidic Al‐toxic soil. This result supports the conclusion that Al tolerance varies among serradella and that some cultivars may not thrive in soils with pHCa < 4.5 and elevated extractable Al concentrations.  相似文献   
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