Smoothing out the misconceptions of the role of bark roughness in vascular epiphyte attachment.

Vascular epiphytes represent c. 10% of all vascular plant species. In epiphytes, attachment is essential for survival throughout consecutive ontogenetic stages of their life, starting with: (1) initial propagule attachment to the host; followed by (2) the development of first root-substrate connections; and (3) maintenance of this attachment despite increased size and mechanical disturbances by rain, wind, or crossing animals. Although structural dependence on a host is a defining characteristic of an epiphyte, the fundamental mechanism(s) of how these plants initially attach and remain attached to their hosts remain poorly understood. Bark characteristics such as stability and roughness have been highlighted as keys to an understanding of this connection. Here, we stress that the understanding of how an epiphyte attaches itself to the substrate is central for a meaningful quantification and interpretation of bark roughness. Without explicit information on the attachment mechanism or the relative sizes of the attaching structures, simply linking a haphazardly chosen index of bark roughness to epiphyte establishment is flawed. This review introduces a conceptual framework to explain the mechanistic link between epiphytes and host in different ontogenetic stages and should guide future work designed to improve our understanding of this vital part of epiphyte ecology.

Holding on or falling off: The attachment mechanism of epiphytic Anthurium obtusum changes with substrate roughness.

PREMISE: For vascular epiphytes, secure attachment to their hosts is vital for survival. Yet studies detailing the adhesion mechanism of epiphytes to their substrate are scarce. Examination of the root hair-substrate interface is essential to understand the attachment mechanism of epiphytes to their substrate. This study also investigated how substrate microroughness relates to the root-substrate attachment strength and the underlying mechanism(s). METHODS: Seeds of Anthurium obtusum were germinated, and seedlings were transferred onto substrates made of epoxy resin with different defined roughness. After 2 months of growth, roots that adhered to the resin tiles were subjected to anchorage tests, and root hair morphology at different roughness levels was analyzed using light and cryo scanning electron microscopy. RESULTS: The highest maximum peeling force was recorded on the smooth surface (glass replica, 0 µm). Maximum peeling force was significantly higher on fine roughness (0, 0.3, 12 µm) than on coarse (162 µm). Root hair morphology varied according to the roughness of the substrate. On smoother surfaces, root hairs were flattened to achieve large surface contact with the substrate. Attachment was mainly by adhesion with the presence of a glue-like substance. On coarser surfaces, root hairs were tubular and conformed to spaces between the asperities on the surface. Attachment was mainly via mechanical interlocking of root hairs and substrate. CONCLUSIONS: This study demonstrates for the first time that the attachment mechanism of epiphytes varies depending on substrate microtopography, which is important for understanding epiphyte attachment on natural substrates varying in roughness.

Go with the flow: The extent of drag reduction as epiphytic bromeliads reorient in wind.

Vascular epiphytes represent almost 10% of all terrestrial plant diversity. Being structurally dependent on trees, epiphytes live at the interface of vegetation and atmosphere, making them susceptible to atmospheric changes. Despite the extensive research on vascular epiphytes, little is known about wind disturbance on these plants. Therefore, this study investigated the wind-epiphyte mechanical interactions by quantifying the drag forces on epiphytic bromeliads when subjected to increasing wind speeds (5-22 m s-1) in a wind tunnel. Drag coefficients (Cd) and Vogel exponents (B) were calculated to quantify the streamlining ability of different bromeliad species. Bromeliads' reconfiguration occurred first via bending and aligning leaves in the flow direction. Then leaves clustered and reduced the overall plant frontal area. This reconfiguration caused drag forces to increase at a slower rate as wind velocity increased. In the extreme case, drag force was reduced by 50% in a large Guzmania monostachia individual at a wind velocity of 22 m s-1, compared to a stiff model. This species had one of the smallest Cd (0.58) at the highest wind velocity, and the largest negative mean B (-0.98), representing the largest reconfiguration capacity amongst the tested bromeliads. The streamlining ability of bromeliads was mainly restricted by the rigidity of the lower part of the plant where the leaves are already densely clustered. Wind speeds used in this study were generally low as compared to storm force winds. At these low wind speeds, reconfiguration was an effective mechanism for drag reduction in bromeliads. This mechanism is likely to lose its effectiveness at higher wind speeds when continuous vigorous fluttering results in leaf damage and aspects such as root-attachment strength and substrate stability become more relevant. This study is a first step towards an understanding of the mechanical bottleneck in the epiphyte-tree-system under wind stress.

Education and support needs in patients with head and neck cancer: A multi-institutional survey.

BACKGROUND: Head and neck cancer (HNC) encompasses a diverse group of tumors, and thus providing appropriate and tailored information to patients before, during, and after treatment is a challenge. The objective of the current study was to characterize the experience and unmet needs of patients with HNC with regard to information and support provision. METHODS: A 28-question, cross-sectional survey was completed by patients treated for HNC at 1 of 4 institutions in New South Wales, Australia (Chris O'Brien Lifehouse and Liverpool, Westmead, and Wollongong hospitals). It consisted of the adapted Kessler Psychological Distress Scale and questions assessing information quality, quantity, and format. RESULTS: A total of 597 patients responded. The mean age of the patients was 58 years (range, 21-94 years) with 284 men and 313 women (1:1.1). The majority of patients reported information concerning the disease process (76%), prognosis (67%), and treatment (77%) was sufficient, and approximately 50% reporting having received little or no information regarding coping with stress and anxiety. A substantial percentage of patients reported receiving minimal information concerning psychosexual health (56%) or the availability of patient support groups (56%). The majority of patients preferred access to multiple modes of information delivery (72%), with the preferred modality being one-on-one meetings with a health educator (37%) followed by internet-based written information (19%). CONCLUSIONS: Patients with HNC are a diverse group, with complex educational and support needs. Patients appear to be given information regarding survivorship topics such as psychological well-being, patient support groups, and psychosexual health less frequently than information concerning disease and treatment. Verbal communication needs to be reinforced by accessible, well-constructed, written and multimedia resources appropriate to the patient's educational level. Cancer 2017;123:1949-1957. © 2017 American Cancer Society.

Diagnostic and prognostic utility of Mastermind-like 2 (MAML2) gene rearrangement detection by fluorescent in situ hybridization (FISH) in mucoepidermoid carcinoma of the salivary glands.

OBJECTIVE: Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy, with a proportion harboring MAML2 rearrangement. This study evaluates the diagnostic and prognostic utility of MAML2 rearrangement in MEC. STUDY DESIGN: Salivary gland malignancies at a single institution (1989-2014) were reviewed to identify MECs. Histopathologic evaluation, immunohistochemistry, and fluorescent in situ hybridization (FISH) were performed. RESULTS: Forty-one cases of MEC were identified, with mean age of 47 years and mean tumor size of 21 mm. Seven locoregional recurrences and five MEC-related deaths were seen over a 22-year follow-up period. Thirty-eight cases were suitable for FISH, and 31 (82%) cases were positive for MAML2 rearrangement, including the oncocytic and clear cell variants of MEC. FISH was negative in the morphologic mimics of MEC. MAML2 rearrangement was significantly associated with longer survival. CONCLUSIONS: MAML2 rearrangement is common and specific for MEC, which makes it a useful diagnostic tool. MAML2 rearrangement also predicts a favorable prognosis.

Kip3, the yeast kinesin-8, is required for clustering of kinetochores at metaphase.

In Saccharomyces cerevisiae, chromosome congression clusters kinetochores on either side of the spindle equator at metaphase. Many organisms require one or more kinesin-8 molecular motors to achieve chromosome alignment. The yeast kinesin-8, Kip3, has been well studied in vitro but a role in chromosome congression has not been reported. We investigated Kip3's role in this process using semi-automated, quantitative fluorescence microscopy and time-lapse imaging and found that Kip3 is required for congression. Deletion of KIP3 increases inter-kinetochore distances and increases the variability in the position of sister kinetochores along the spindle axis during metaphase. Kip3 does not regulate spindle length and is not required for kinetochore-microtubule attachment. Instead, Kip3 clusters kinetochores on the metaphase spindle by tightly regulating kinetochore microtubule lengths.

Steroid and xenobiotic receptor and vitamin D receptor crosstalk mediates CYP24 expression and drug-induced osteomalacia.

The balance between bioactivation and degradation of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is critical for ensuring appropriate biological effects of vitamin D. Cytochrome P450, family 24-mediated (CYP24-mediated) 24-hydroxylation of 1,25(OH)2D3 is an important step in the catabolism of 1,25(OH)2D3. The enzyme is directly regulated by vitamin D receptor (VDR), and it is expressed mainly in the kidney, where VDR is also abundant. A recent report suggests that activation of steroid and xenobiotic receptor (SXR) also enhances the expression of CYP24, providing a new molecular mechanism of drug-induced osteomalacia. However, here we showed that activation of SXR did not induce CYP24 expression in vitro and in vivo, nor did it transactivate the CYP24 promoter. Instead, SXR inhibited VDR-mediated CYP24 promoter activity, and CYP24 expression was very low in tissues containing high levels of SXR, including the small intestine. Moreover, 1,25(OH)2D3-induced CYP24 expression was enhanced in mice lacking the SXR ortholog pregnane X receptor, and treatment of humans with the SXR agonist rifampicin had no effect on intestinal CYP24 expression, despite demonstration of marked CYP3A4 induction. Combined with our previous findings that CYP3A4, not CYP24, plays the dominant role in hydroxylation of 1,25(OH)2D3 in human liver and intestine, our results indicate that SXR has a dual role in mediating vitamin D catabolism and drug-induced osteomalacia.