Effect of oxygen on the germination and culturability of Bacillus atrophaeus spores

The effect of oxygen on the germination and culturability of aerobic Bacillus atrophaeus spores was investigated in this study. Under oxic or anoxic conditions, various nutritional and non-nutritional germinants were utilized to induce germination. Tb3+-dipicolinic acid fluorescence assay and phase-contrast microscopy were used to track the germination process. The final germination level, germination half time, and germination speed were used to define germination kinetics. Colony-forming unit enumeration was used to assess the culturability of germinated spores germinated with or without oxygen. The results show that in the absence of oxygen, the final germination level was unaffected, germination half time decreased by up to 35.0%, germination speed increased by up to 27.4%, and culturability decreased by up to 95.1%. It is suggested that oxygen affects some germinant receptor-dependent germination pathways, implying that biomolecules engaged in these pathways may be oxygen-sensitive. Furthermore, spores that have completed the germination process in either anoxic or oxic conditions may have different culturability. This research contributed to a better understanding of the fundamental mechanism of germination.

Comparison of Segmentation Performance of Activated Sludge Flocs Using Bright-Field and Phase-Contrast Microscopy at Different Magnifications

Activated sludge (AS) is a type of process which is commonly used for the treatment of sewage and industrial wastewater. In this treatment process, the settling of the sludge flocs is important to ensure the normal functioning of the system, while sludge bulking has become a common and long-term problem that greatly affects floc settleability. Thus, methods based on image processing and analysis are introduced for monitoring AS wastewater treatment plants. However, the effectiveness of using image processing methods heavily depends on the performance of segmentation algorithms. The AS wastewater plant can be monitored through microscopic images of the flocs and filaments. Water samples are taken from the aeration tank of the wastewater plants and then observed using bright field and phase-contrast microscopy to compare the segmentation accuracy at different magnifications i.e., 4x, 10x, 20x, 40x. In this paper, three methods to segment and quantify the flocs in bright field and phase-contrast microscopy images have been analyzed. The first method is image segmentation using Bradley local thresholding method, the second method is texture segmentation using range filtering and Otsu’s thresholding and the third method is Gaussian Mixture Method based segmentation. The experimental results show that Gaussian Mixture Model Method gives the best segmentation accuracy for bright-field microscopy and 10x magnification gives the best results.

Oncholaimus tripapillatus sp. nov., a New Free-Living Marine Nematode of the Genus Oncholaimus Dujardin, 1845 (Nematoda: Enoplida: Oncholaimidae) from the Subtidal Sediment of Dokdo Island, East Sea, Korea, with a New Record of O. qingdaoensis Zhang & Platt, 1983

During a survey of the free-living marine nematodes of Korea, two species belonging to the genus Oncholaimus Dujardin, 1845 were discovered. A new species, Oncholaimus tripapillatus sp. nov. and a newly recorded species, Oncholaimus qingdaoensis Zhang & Platt, 1983, are reported. Oncholaimus tripapillatus sp. nov. was collected from the washing of subtidal coarse sediments around Dokdo Island of the East Sea, Korea. Oncholaimus tripapillatus sp. nov. is characterized by a relatively long (4071–4435 µm in males and 4514–4661 µm in females) and slender body, a slightly constricted head region, relatively long cephalic setae (10–12 µm), males having a precloacal sexual protuberance bearing two small cone-shaped supplementary spines, five pairs of long cloacal setae (three pairs of precloacal and two pairs of postcloacal setae in subventral position), and three remarkable papillae near the end of the tail, with two pairs of subventral setae. The Korean specimens of Oncholaimus qingdaoensis Zhang & Platt, 1983 are almost identical to the Chinese specimens of the original description from the intertidal sand of Qingdao, China. However, the Korean specimens differ from the Chinese specimens in the longer body length in males (3379–3715 µm vs. 2380–2640 µm), the larger spicule length (47–52 µm vs. 34–36 µm), and the presence of ventral tail papillae situated around 14–16 µm from the tail tip. Detailed morphological features and illustrations of two Oncholaimus species from Korea were obtained by differential interference contrast microscopy and scanning electron microscopy. A pictorial key to the species group with distinct tail papillae among the genus Oncholaimus is also provided.

Metastatic Prostate Cancer Cells Secrete Methylglyoxal-Derived MG-H1 to Reprogram Human Osteoblasts into a Dedifferentiated, Malignant-Like Phenotype: A Possible Novel Player in Prostate Cancer Bone Metastases

Bone metastases from prostate cancer (PCa) result from a complex cross-talk between PCa cells and osteoblasts (OB). Thus, targeting this interplay has become an attractive strategy to interfere with PCa bone dissemination. The agents currently used in clinical trials have proved ineffective, boosting research to identify additional mechanisms that may be involved in this two-directional talk. Here, we investigated whether and how 5-hydro-5-methylimidazolone (MG-H1), a specific methylglyoxal (MG)-derived advanced glycation end product (AGE), was a novel player in the dialogue between PCa and OB to drive PCa bone metastases. Conditioned medium from osteotropic PC3 PCa cells, pre-treated or not with a specific MG scavenger, was administrated to human primary OB and cell morphology, mesenchymal trans-differentiation, pro-osteogenic determinants, PCa-specific molecules, and migration/invasion were studied by phase-contrast microscopy, real-time PCR, western blot and specific assays, respectively. We found that PC3 cells were able to release MG-H1 that, by binding to the receptor for AGEs (RAGE) on OB, reprogrammed them into a less-differentiate phenotype, endowed with some PCa-specific molecular features and malignant properties, in a mechanism involving reactive oxidative species (ROS) production and NF-kB pathway activation. These findings provide novel insights into the mechanisms of PCa osteoblastic metastases and foster in vivo research toward new therapeutic strategies interfering with PCa/OB cross-talk.