Sugars and sucrose transporters in pollinia of Phalaenopsis aphrodite (Orchidaceae).

The pollen grains of Phalaenopsis orchids are clumped tightly together, packed in pollen dispersal units called pollinia. In this study, the morphology, cytology, biochemistry, and sucrose transporters in pollinia of Phalaenopsis orchids were investigated. Histochemical detection was used to characterize the distribution of sugars and callose at the different development stages of pollinia. Ultra-performance liquid chromatography-high resolution-tandem mass spectrometry data indicated that P. aphrodite accumulated abundant saccharides such as sucrose, galactinol, myo-inositol, and glucose, and trace amounts of raffinose and trehalose in mature pollinia. We found that galactinol synthase (PAXXG304680) and trehalose-6-phosphate phosphatase (PAXXG016120) genes were preferentially expressed in mature pollinia. The P. aphrodite genome was identified as having 11 sucrose transporters (SUTs). Our qRT-PCR confirmed that two SUTs (PAXXG030250 and PAXXG195390) were preferentially expressed in the pollinia. Pollinia germinated in pollen germination media (PGM) supplemented with 10% sucrose showed increased callose production and enhanced pollinia germination, but there was no callose or germination in PGM without sucrose. We show that P. aphrodite accumulates high levels of sugars in mature pollinia, providing nutrients and enhanced SUT gene expression for pollinia germination and tube growth.

[Hemoglobin C Variant Affecting Glycated Hemoglobin Test Results: A Rare Case Report].

Hemoglobin (Hb) variants are common factors that affect the results of glycosylated hemoglobin (A1C) tests. Hemoglobin variants react differently to different testing methods. Herein, we presented the first ever report of the effect of hemoglobin C (Hb C) on the test results of A1C in the Chinese population. High performance liquid chromatography (HPLC) and capillary electrophoresis were performed to measure A1C. Hemoglobin electrophoresis was conducted to identify the hemoglobin variants. Hb sequencing was performed to determine the mutation sites on the ß chain. HPLC showed decreased A1C results, which could be corrected by electrophoresis, but the electrophoresis graph still showed abnormal peaks. The hemoglobin electrophoresis results suggested that there were hemoglobin variants, which hemoglobin sequencing results revealed to be Hb C. Uncommon variations in a specific population tend to be overlooked. To avoid clinical decision-making being affected by the results of a single test, we recommend that an explanatory reporting model be routinely adopted for A1C tests so that all reports always contain explanatory notes for the testing methodology and analysis of the graphs.

Structural insights into the interaction between phytoplasmal effector causing phyllody 1 and MADS transcription factors.

Phytoplasmas are bacterial plant pathogens which can induce severe symptoms including dwarfism, phyllody and virescence in an infected plant. Because phytoplasmas infect many important crops such as peanut and papaya they have caused serious agricultural losses. The phytoplasmal effector causing phyllody 1 (PHYL1) is an important phytoplasmal pathogenic factor which affects the biological function of MADS transcription factors by interacting with their K (keratin-like) domain, thus resulting in abnormal plant developments such as phyllody. Until now, lack of information on the structure of PHYL1 has prevented a detailed understanding of the binding mechanism between PHYL1 and the MADS transcription factors. Here, we present the crystal structure of PHYL1 from peanut witches'-broom phytoplasma (PHYL1PnWB ). This protein was found to fold into a unique α-helical hairpin with exposed hydrophobic residues on its surface that may play an important role in its biological function. Using proteomics approaches, we propose a binding mode of PHYL1PnWB with the K domain of the MADS transcription factor SEPALLATA3 (SEP3_K) and identify the residues of PHYL1PnWB that are important for this interaction. Furthermore, using surface plasmon resonance we measure the binding strength of PHYL1PnWB proteins to SEP3_K. Lastly, based on confocal images, we found that α-helix 2 of PHYL1PnWB plays an important role in PHYL1-mediated degradation of SEP3. Taken together, these results provide a structural understanding of the specific binding mechanism between PHYL1PnWB and SEP3_K.