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Saccharomyces cerevisiae vacuole inheritance requires two low molecular weight activities, LMA1 and LMA2. LMA1 is a heterodimer of thioredoxin and protease B inhibitor 2 [Mathematical Expression Omitted]. Here we show that the second low molecular weight activity (LMA2) is monomeric [Mathematical Expression Omitted]. Though [Mathematical Expression Omitted] was initially identified as a protease B inhibitor, this protease inhibitor activity is not related to its ability to promote vacuole fusion: (i) Low [M.sub.r] protease B inhibitors cannot substitute for LMA1 or LMA 2, (ii) LMA1 and LMA2 promote the fusion of vacuoles from a strain that has no protease B, (iii) low concentrations of LMA2 that fully inhibit protease B do not promote vacuole fusion, and (iv) LMA1, in which [Mathematical Expression Omitted] is complexed with thioredoxin, is far more active than [Mathematical Expression Omitted] in promoting vacuole fusion and far less active in inhibiting protease B. These studies establish a new function for [Mathematical Expression Omitted].

The mechanism involved in vacuole inheritance in Saccharomyces cerevisiae was investigated using in vitro homotypic vacuole fusion assay, supplemented by gel filtration and fluorescence microscopy. The experiments identified I(super B)(sub 2) as a novel second subunit of LMA1, a heterodimer with a thioredoxin subunit which has been known to mediate homotypic fusion of vacuoles together with an N-ethylmaleimide-sensitive soluble protein, Sec18p. It was also demonstrated that the ordered synergistic action of LMA1 and Sec18p occurs at an early stage of the vacuole inheritance reaction.

Vacuole fusion occurs in three stages: priming, in which Sec18p mediates Secl7p release, LMA1 (low [M.sub.r] activity 1) relocation, and cis-SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex disassembly; docking, mediated by Ypt7p and trans-SNARE association; and fusion of docked vacuoles. [Ca.sup.2+] and calmodulin regulate late stages of the reaction. We now show that the vacuole proton gradient, generated by the vacuolar proton ATPase, is needed for trans-SNARE complex formation during docking and hence for the subsequent LMA1 release. Though neither the vacuolar Pmc1p [Ca.sup.2+]-ATPase nor the Vcx1p [Ca.sup.2+]/[H.sup.+] exchanger are needed for the fusion reaction, they participate in [Ca.sup.2+] and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], homeostasis. Fusion itself does not require the maintenance of trans-SNARE pairs.

Points out that I... is a small cytosolic protein which participates in vacuole fusion. Information on saccharomyces cerevisiae vacuole inheritance; Reference to the defective nature of vacuole inheritance mutants; Details on vacuole fusion.

Purpose: Precisely detecting colorectal liver metastases (CLMs), the leading cause of colorectal cancer-associated mortality, is extremely important. 1 H MRI with high soft tissue resolution plays a key role in the diagnosing liver lesions; however, precise detecting CLMs by 1 H MRI is a great challenge due to the limited sensitivity. Even though contrast agents may improve the sensitivity, due to their short half-life, repeated injections are required to monitor the changes of CLMs. Herein, we synthesized c-Met-targeting peptide-functionalized perfluoro-15-crown-5-ether nanoparticles (AH111972-PFCE NPs), for highly sensitive and early diagnosis of small CLMs., Methods: The size, morphology and optimal properties of the AH111972-PFCE NPs were characterized. c-Met specificity of the AH111972-PFCE NPs was validated by in vitro experiment and in vivo 19 F MRI study in the subcutaneous tumor murine model. The molecular imaging practicability and long tumor retention of the AH111972-PFCE NPs were evaluated in the liver metastases mouse model. The biocompatibility of the AH111972-PFCE NPs was assessed by toxicity study., Results: AH111972-PFCE NPs with regular shape have particle size of 89.3 ± 17.8 nm. The AH111972-PFCE NPs exhibit high specificity, strong c-Met-targeting ability, and precise detection capability of CLMs, especially small or ill-defined fused metastases in 1 H MRI. Moreover, AH111972-PFCE NPs could be ultralong retained in metastatic liver tumors for at least 7 days, which is conductive to the implementation of continuous therapeutic efficacy monitoring. The NPs with minimal side effects and good biocompatibility are cleared mainly via the spleen and liver., Conclusion: The c-Met targeting and ultralong tumor retention of AH111972-PFCE NPs will contribute to increasing therapeutic agent accumulation in metastatic sites, laying a foundation for CLMs diagnosis and further c-Met targeted treatment integration. This work provides a promising nanoplatform for the future clinical application to patients with CLMs., Competing Interests: The authors report no conflicts of interest in this work., (© 2023 Li et al.)

Hypoxia is a common feature of solid tumors that is closely associated with radiotherapy and chemotherapy resistance, metastasis and tumors prognosis. Thus, it is important to assess hypoxia in tumors for estimating prognosis and selecting appropriate treatment procedures. 18 F-Fluoromisonidazole positron emission tomography ( 18 F-FMISO PET) has been widely used to visualize tumor hypoxia in a comprehensive and noninvasive way, both in the clinical and preclinical settings. Here we review the concept, mechanisms and detection methods of tumor hypoxia. Furthermore, we discuss the correlation between 18 F-FMISO PET and other detection methods, current applications of 18 F-FMISO PET and the development prospects of this imaging technology., Competing Interests: CONFLICTS OF INTEREST The authors declare that they have no conflicts of interest.