Identification of a key signaling network regulating perennating bud dormancy in Panax ginseng.

Background: The cycle of seasonal dormancy of perennating buds is an essential adaptation of perennial plants to unfavorable winter conditions. Plant hormones are key regulators of this critical biological process, which is intricately connected with diverse internal and external factors. Recently, global warming has increased the frequency of aberrant temperature events that negatively affect the dormancy cycle of perennials. Although many studies have been conducted on the perennating organs of Panax ginseng, the molecular aspects of bud dormancy in this species remain largely unknown. Methods: In this study, the molecular physiological responses of three P. ginseng cultivars with different dormancy break phenotypes in the spring were dissected using comparative genome-wide RNA-seq and network analyses. These analyses identified a key role for abscisic acid (ABA) activity in the regulation of bud dormancy. Gene set enrichment analysis revealed that a transcriptional network comprising stress-related hormone responses made a major contribution to the maintenance of dormancy. Results: Increased expression levels of cold response and photosynthesis-related genes were associated with the transition from dormancy to active growth in perennating buds. Finally, the expression patterns of genes encoding ABA transporters, receptors (PYRs/PYLs), PROTEIN PHOSPHATASE 2Cs (PP2Cs), and DELLAs were highly correlated with different dormancy states in three P. ginseng cultivars. Conclusion: This study provides evidence that ABA and stress signaling outputs are intricately connected with a key signaling network to regulate bud dormancy under seasonal conditions in the perennial plant P. ginseng.

Efficient Somatic Embryogenesis, Regeneration and Acclimatization of Panax ginseng Meyer: True-to-Type Conformity of Plantlets as Confirmed by ISSR Analysis.

Panax ginseng Meyer grows in east Russia and Asia. There is a high demand for this crop due to its medicinal properties. However, its low reproductive efficiency has been a hindrance to the crop's widespread use. This study aims to establish an efficient regeneration and acclimatization system for the crop. The type of basal media and strength were evaluated for their effects on somatic embryogenesis, germination, and regeneration. The highest rate of somatic embryogenesis was achieved for the basal media MS, N6, and GD, with the optimal nitrogen content (≥35 mM) and NH4+/NO3- ratio (1:2 or 1:4). The full-strength MS medium was the best one for somatic embryo induction. However, the diluted MS medium had a more positive effect on embryo maturation. Additionally, the basal media affected shooting, rooting, and plantlet formation. The germination medium containing 1/2 MS facilitated good shoot development; however, the medium with 1/2 SH yielded outstanding root development. In vitro-grown roots were successfully transferred to soil, and they exhibited a high survival rate (86.3%). Finally, the ISSR marker analysis demonstrated that the regenerated plants were not different from the control. The obtained results provide valuable information for a more efficient micropropagation of various P. ginseng cultivars.

Angioleiomyoma of the Parotid Gland Fed by the Superficial Temporal Artery.

Angioleiomyoma in the head and neck area is rarely observed. This report introduces 2 cases of angioleiomyoma discovered in the parotid gland, particularly with the superficial temporal artery (STA) as the feeding vessel. Each patient was evaluated preoperatively by clinical manifestation and computed tomography scan, but the difficulty was encountered due to nonspecific radiologic features of angioleiomyoa. Surgical intervention was performed for precise diagnosis and treatment. The tumors were fed from the STA, with the diagnosis of venous type parotid angioleiomyoma. To our knowledge, there have been only one previous report of angioleiomyoma of the parotid gland fed from STA in the literature. Once parotid tumor is discovered, although rare, the possibility of angioleiomyoma should be considered, and the authors recommend prompt surgical excision for accurate diagnosis and treatment.

Ultra-wide band (O to L) photonic integrated polymer cross-bar switch matrix.

We present an ultra-wide band photonic integrated 4×4 polymer cross-bar switch matrix based on total internal reflection and the thermo-optic effect. The photonic integrated polymer switch owns low insertion loss, low power consumption, wavelength, and polarization-independent operation for all switching paths. The experimental results show ultra-wide band (O- to L-band) operation with fiber-to-fiber insertion losses ranging from -3.7 to -6.5dB, 0.1 to 0.6 dB polarization-dependent losses, switching the on-off ratio above 36 dB on average, and 25 mW power consumption per path. Error-free operation with a power penalty <0.2dB at 1 E-9 bit error rate (BER) for ultra-wide band non-return-to-zero on-off keying (NRZ-OOK) wavelength-division multiplexing (WDM) switched signals at 10, 25, 40, and 50 Gbit/s, and 510 Gbps dual polarization 64-QAM switched data with a negligible penalty were measured.

Full-Thickness Skin Graft according to Surrounding Relaxed Skin Tension Line Improves Scar Quality in Facial Defect Coverage: A Retrospective Comparative Study.

A full-thickness skin graft (FTSG) is useful for covering small skin and soft tissue defects. In this paper, we suggest FTSG in consideration of the relaxed skin tension line (RSTL) concept for scar quality improvement since FTSG has disadvantages, including contour irregularities and mismatches of color and texture. We conducted a retrospective chart review of twenty-one patients with skin cancer on the face who underwent wide excision and FTSG by a single surgeon from October 2013 to July 2019. Twenty-one patients with skin cancer on the face were divided into RSTL-matched and RSTL-unmatched groups, and FTSG was performed. Each group was subjected to scar assessment three months after surgery. Observer assessment was performed by five independent observers using the observer component of the patient and observer scar assessment scale (POSAS) and Vancouver scar scale (VSS). Our results indicate that there were significant differences between the RSTL-matched and RSTL-unmatched groups in the VSS and POSAS components. In addition, the RSTL-matched group showed a natural appearance with surrounding tissue in the dynamic animation phase compared to the unmatched group. RSTL-matched FTSG can be an attractive option for face skin and soft tissue defect coverage. (An earlier version of this paper has been presented at the International Conference on PRS Korea 2020.).

Shape memory alloy as an internal splint in a rat model of excisional wound healing.

The purpose of an animal wound model is to replicate the wound healing process of humans as accurately as possible. Although rodents are attractive candidates for animal wound models, the drawback is that their major wound healing occurs by contraction, which is fundamentally different from that seen in humans, where healing is achieved mainly by re-epithelialization and granulation tissue growth. There has been an attempt to overcome such drawbacks by applying an external splint on wounded mice. This model, however, has a few problems concerning the assimilating ability of external splints with the dynamic soft tissue movements and robustness issues. The authors hereby describe a new animal wound model using an internal splint made of nitinol, one of the shape memory alloys (SMAs). SMA wire was inserted intradermally around the full-thickness excisional wound to act as the internal splint, and its ability to impede wound contraction was analyzed. In experiment 1, three different sizes of SMAs (0.18 mm, 0.24 mm, and 0.30 mm diameters of thickness) were inserted as the internal splint and their ability to impede the wound contraction was compared. The most effective size of SMA as the internal splint was selected among them. In experiment 2, contraction of the wound with the selected size of SMA inserted as the internal splint was compared with that of the unsplinted wound. SMA as an internal splint effectively impeded wound contraction without affecting the re-epithelialization rate, thereby successfully mimicking the human wound healing mechanism. In this study, the authors introduce a novel animal wound model that replicates the human wound healing mechanism. This model is robust, reliable, and easily reproducible.

Comparative Analysis of Panax ginseng Berries from Seven Cultivars Using UPLC-QTOF/MS and NMR-Based Metabolic Profiling.

The commercial use of Panax ginseng berries is increasing as P. ginseng berries are known to contain large amounts of ginsenosides, and many pharmacological activities have been reported for the various ginsenosides. For the proper use of P.ginseng berries, it is necessary to study efficient and accurate quality control and the profiling of the overall composition of each cultivar. Ginseng berry samples from seven cultivars (Eumseung, Chung-buk Province, Republic of Korea) were analyzed using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-QTOF/MS) for profiling of the ginsenosides, and high-resolution magic-angle-spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy for profiling of the primary metabolites. Comparing twenty-six ginsenoside profiles between the variant representatives and between the violet-stem variant, Kumpoong and Sunwon were classified. In the case of primary metabolites, the cultivars Kumpoong and Gopoong were classified. As a result of correlation analyses of the primary and secondary metabolites, in the Gopoong cultivar, the metabolism was found to lean toward energy metabolism rather than ginsenoside synthesis, and accumulation of osmolytes was low. The Gopoong cultivar had higher levels of most of the amino acids, such as arginine, phenylalanine, isoleucine, threonine, and valine, and it contained the highest level of choline and the lowest level of myo-inositol. Except for these, there were no significant differences of primary metabolites. In the Kumpoong cultivar, the protopanaxatriol (PPT)-type ginsenosides, ginsenoside Re and ginsenoside Rg2, were much lower than in the other cultivars, while the other PPT-type ginsenosides were inversely found in much higher amounts than in other cultivars. The Sunwon cultivar showed that variations of PPT-type ginsenosides were significantly different between samples. However, the median values of PPT-type ginsenosides of Sunwon showed similar levels to those of Kumpoong. The difference in primary metabolites used for metabolism for survival was found to be small in our results. Our data demonstrated the characteristics of each cultivar using profiling data of the primary and secondary metabolites, especially for Gopoong, Kumpoong, and Sunwon. These profiling data provided important information for further research and commercial use.

Metagenomic analysis of bacterial endophyte community structure and functions in Panax ginseng at different ages.

This study investigated the root-associated bacterial endophytes of Panax ginseng at different ages by shotgun metagenomic analysis. After mapping metagenome data to the complete ginseng genome to identify unmapped sequences, we predicted the structure and functions of ginseng bacterial endophytes by metagenomic rapid annotation using subsystems technology analysis. While Proteobacteria and Actinobacteria were the predominant phyla in all samples (2-6-year-old roots), class Alphaproteobacteria was most abundant in 3-, 4-, and 5-year-old plants. We found that 3-year-old P. ginseng had a 0.66% unmapped rate against the whole ginseng genome and showed the greatest diversity of endophytic bacteria (α diversity = 299). Prediction of endophytic bacterial functions at different ages by SEED subsystem analysis revealed that siderophore and auxin-related traits-which are known to promote plant growth-were most highly represented in 3-year-old plants. This was supported by a gene frequency analysis of plant growth-promoting genes, including those responsible for solubilization of phosphate and nitrogen metabolism, using BLASTn. These results suggest that endophytic bacteria of the P. ginseng root affect plant growth. Furthermore, the isolation and purification of plant growth-promoting endophytes identified in this study could promote sustainable cultivation of ginseng in the future.

Complete Genome Sequence of the Endophytic Bacterium Chryseobacterium indologenes PgBE177, Isolated from Panax quinquefolius.

Chryseobacterium indologenes PgBE177, isolated from the root tissue of a 4-year-old Panax quinquefolius plant, showed antagonistic activity against Pseudomonas syringae pv. tomato DC3000, a bacterial pathogen. Here, we report the whole-genome sequence of C. indologenes PgBE177. The bacterium contains bacteriocin gene clusters and has the potential to stimulate plant growth.

Complete Genome Sequence of the Endophytic Bacterium Bacillus cereus PgBE311, Isolated from Panax ginseng.

Bacillus cereus PgBE311, isolated from the root tissue of a 5-year-old Panax ginseng plant, showed activities against the fungal pathogens Cylindrocarpon destructans and Botrytis cinerea. Here, we report the genome sequence of B. cereus PgBE311. The bacterium contains antibiotic-related gene clusters and has the potential to stimulate plant growth.

C/N/O/S stable isotopic and chemometric analyses for determining the geographical origin of Panax ginseng cultivated in Korea.

BACKGROUND: The geographical origin of Panax ginseng Meyer, a valuable medicinal plant, is important to both ginseng producers and consumers in the context of economic profit and human health benefits. We, therefore, aimed to discriminate between the cultivation regions of ginseng using the stable isotope ratios of C, N, O, and S, which are abundant bioelements in living organisms. METHODS: Six Korean ginseng cultivars (3-yr-old roots) were collected from five different regions in Korea. The C, N, O, and S stable isotope ratios in ginseng roots were measured by isotope ratio mass spectrometry, and then these isotope ratio profiles were statistically analyzed using chemometrics. RESULTS: The various isotope ratios found in P. ginseng roots were significantly influenced by region, cultivar, and the interactions between these two factors (p ≤ 0.001). The variation in δ15N and δ13C in ginseng roots was significant for discriminating between different ginseng cultivation regions, and δ18O and δ34S were also affected by both altitude and proximity to coastal areas. Chemometric model results tested in this study provided discrimination between the majority of different cultivation regions. Based on the external validation, this chemometric model also showed good model performance (R 2 = 0.853 and Q 2 = 0.738). CONCLUSION: Our case study elucidates the variation of C, N, O, and S stable isotope ratios in ginseng root depending on cultivation region. Hence, the analysis of stable isotope ratios is a suitable tool for discrimination between the regional origins of ginseng samples from Korea, with potential application to other countries.

Diversity of bacterial endophytes in Panax ginseng and their protective effects against pathogens.

Although endophytic bacteria are known to colonize Panax ginseng, little is known about their diversity and roles. We addressed in the present study by comparing endophytic bacterial populations in P. ginseng plants of different ages (2-6 years) and in various tissue types (root, stem, leaf, and flower stalk). A total of 116 strains assigned to 42 species were identified by 16S rDNA sequencing. The predominant phylum was Firmicutes. Two-year-old ginseng plants and root tissues showed the greatest diversity of endophytic bacteria, with Bacillales being the predominant order. The antifungal activity of isolates against two pathogens, Cylindrocarpon destructans and/or Botrytis cinerea, was evaluated in dual-culture assays. In total, 28 strains showed antifungal activity with PgBE14 (Bacillus amyloliquefaciens), PgBE40 (B. megaterium), PgBE39, PgBE45 (Pseudomonas frederiksbergensis), and PgBE42 (Staphylococcus saprophyticus) inhibiting both pathogens. These results improve our understanding of the structure and diversity of endophytic bacterial communities of P. ginseng and identify strains with antifungal activity that have potential applications as biocontrol agents.

Application of AutoFom III equipment for prediction of primal and commercial cut weight of Korean pig carcasses.

OBJECTIVE: This study was conducted to enable on-line prediction of primal and commercial cut weights in Korean slaughter pigs by AutoFom III, which non-invasively scans pig carcasses early after slaughter using ultrasonic sensors. METHODS: A total of 162 Landrace, Yorkshire, and Duroc (LYD) pigs and 154 LYD pigs representing the yearly Korean slaughter distribution were included in the calibration and validation dataset, respectively. Partial least squares (PLS) models were developed for prediction of the weight of deboned shoulder blade, shoulder picnic, belly, loin, and ham. In addition, AutoFom III´s ability to predict the weight of the commercial cuts of spare rib, jowl, false lean, back rib, diaphragm, and tenderloin was investigated. Each cut was manually prepared by local butchers and then recorded. RESULTS: The cross-validated prediction accuracy (R2cv) of the calibration models for deboned shoulder blade, shoulder picnic, loin, belly, and ham ranged from 0.77 to 0.86. The R2cv for tenderloin, spare rib, diaphragm, false lean, jowl, and back rib ranged from 0.34 to 0.62. Because the R2cv of the latter commercial cuts were less than 0.65, AutoFom III was less accurate for the prediction of those cuts. The root mean squares error of cross validation calibration (RMSECV) model was comparable to the root mean squares error of prediction (RMSEP), although the RMSECV was numerically higher than RMSEP for the deboned shoulder blade and belly. CONCLUSION: AutoFom III predicts the weight of deboned shoulder blade, shoulder picnic, loin, belly, and ham with high accuracy, and is a suitable process analytical tool for sorting pork primals in Korea. However, AutoFom III's prediction of smaller commercial Korean cuts is less accurate, which may be attributed to the lack of anatomical reference points and the lack of a good correlation between the scanned area of the carcass and those traits.

The mRNA and miRNA transcriptomic landscape of Panax ginseng under the high ambient temperature.

BACKGROUND: Ginseng is a popular traditional herbal medicine in north-eastern Asia. It has been used for human health for over thousands of years. With the rise in global temperature, the production of Korean ginseng (Panax ginseng C.A.Meyer) in Korea have migrated from mid to northern parts of the Korean peninsula to escape from the various higher temperature related stresses. Under the high ambient temperature, vegetative growth was accelerated, which resulted in early flowering. This precocious phase change led to yield loss. Despite of its importance as a traditional medicine, biological mechanisms of ginseng has not been well studied and even the genome sequence of ginseng is yet to be determined due to its complex genome structure. Thus, it is challenging to investigate the molecular biology mechanisms at the transcript level. RESULTS: To investigate how ginseng responds to the high ambient temperature environment, we performed high throughput RNA sequencing and implemented a bioinformatics pipeline for the integrated analysis of small-RNA and mRNA-seq data without a reference genome. By performing reverse transcriptase (RT) PCR and sanger sequencing of transcripts that were assembled using our pipeline, we validated that their sequences were expressed in our samples. Furthermore, to investigate the interaction between genes and non-coding small RNAs and their regulation status under the high ambient temperature, we identified potential gene regulatory miRNAs. As a result, 100,672 contigs with significant expression level were identified and 6 known, 214 conserved and 60 potential novel miRNAs were predicted to be expressed under the high ambient temperature. CONCLUSION: Collectively, we have found that development, flowering and temperature responsive genes were induced under high ambient temperature, whereas photosynthesis related genes were repressed. Functional miRNAs were down-regulated under the high ambient temperature. Among them are miR156 and miR396 that target flowering (SPL6/9) and growth regulating genes (GRF) respectively.

A Novel Multifunctional C-23 Oxidase, CYP714E19, is Involved in Asiaticoside Biosynthesis.

Centella asiatica is widely used as a medicinal plant due to accumulation of the ursane-type triterpene saponins asiaticoside and madecassoside. The molecular structure of both compounds suggests that they are biosynthesized from α-amyrin via three hydroxylations, and the respective Cyt P450-dependent monooxygenases (P450 enzymes) oxidizing the C-28 and C-2α positions have been reported. However, a third enzyme hydroxylating C-23 remained elusive. We previously identified 40,064 unique sequences in the transcriptome of C. asiatica elicited by methyl jasmonate, and among them we have now found 149 unigenes encoding putative P450 enzymes. In this set, 23 full-length cDNAs were recognized, 13 of which belonged to P450 subfamilies previously implicated in secondary metabolism. Four of these genes were highly expressed in response to jasmonate treatment, especially in leaves, in accordance with the accumulation patterns of asiaticoside. The functions of these candidate genes were tested using heterologous expression in yeast cells. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that yeast expressing only the oxidosqualene synthase CaDDS produced the asiaticoside precursor α-amyrin (along with its isomer ß-amyrin), while yeast co-expressing CaDDS and CYP716A83 also contained ursolic acid along with oleanolic acid. This P450 enzyme thus acts as a multifunctional triterpenoid C-28 oxidase converting amyrins into corresponding triterpenoid acids. Finally, yeast strains co-expressing CaDDS, CYP716A83 and CYP714E19 produced hederagenin and 23-hydroxyursolic acid, showing that CYP714E19 is a multifunctional triterpenoid oxidase catalyzing the C-23 hydroxylation of oleanolic acid and ursolic acid. Overall, our results demonstrate that CaDDS, CYP716A83 and CYP714E19 are C. asiatica enzymes catalyzing consecutive steps in asiaticoside biosynthesis.

Isoform Sequencing Provides a More Comprehensive View of the Panax ginseng Transcriptome.

Korean ginseng (Panax ginseng C.A. Meyer) has been widely used for medicinal purposes and contains potent plant secondary metabolites, including ginsenosides. To obtain transcriptomic data that offers a more comprehensive view of functional genomics in P. ginseng, we generated genome-wide transcriptome data from four different P. ginseng tissues using PacBio isoform sequencing (Iso-Seq) technology. A total of 135,317 assembled transcripts were generated with an average length of 3.2 kb and high assembly completeness. Of those unigenes, 67.5% were predicted to be complete full-length (FL) open reading frames (ORFs) and exhibited a high gene annotation rate. Furthermore, we successfully identified unique full-length genes involved in triterpenoid saponin synthesis and plant hormonal signaling pathways, including auxin and cytokinin. Studies on the functional genomics of P. ginseng seedlings have confirmed the rapid upregulation of negative feed-back loops by auxin and cytokinin signaling cues. The conserved evolutionary mechanisms in the auxin and cytokinin canonical signaling pathways of P. ginseng are more complex than those in Arabidopsis thaliana. Our analysis also revealed a more detailed view of transcriptome-wide alternative isoforms for 88 genes. Finally, transposable elements (TEs) were also identified, suggesting transcriptional activity of TEs in P. ginseng. In conclusion, our results suggest that long-read, full-length or partial-unigene data with high-quality assemblies are invaluable resources as transcriptomic references in P. ginseng and can be used for comparative analyses in closely related medicinal plants.

Role of Atypical Pathogens and the Antibiotic Prescription Pattern in Acute Bronchitis: A Multicenter Study in Korea.

The role of atypical bacteria and the effect of antibiotic treatments in acute bronchitis are still not clear. This study was conducted at 22 hospitals (17 primary care clinics and 5 university hospitals) in Korea. Outpatients (aged ≥ 18 yr) who had an acute illness with a new cough and sputum (≤ 30 days) were enrolled in 2013. Multiplex real-time polymerase chain reaction (RT-PCR) was used to detect five atypical bacteria. A total of 435 patients were diagnosed as having acute bronchitis (vs. probable pneumonia, n = 75), and 1.8% (n = 8) were positive for atypical pathogens (Bordetella pertussis, n = 3; B. parapertussis, n = 0; Mycoplasma pneumoniae, n = 1; Chlamydophila pneumoniae, n = 3; Legionella pneumophila, n = 1). Among clinical symptoms and signs, only post-tussive vomiting was more frequent in patients with atypical pathogens than those without (P = 0.024). In all, 72.2% of the enrolled patients received antibiotic treatment at their first visits, and ß-lactams (29.4%) and quinolones (20.5%) were the most commonly prescribed agents. In conclusion, our study demonstrates that the incidence of atypical pathogens is low in patients with acute bronchitis, and the rate of antibiotic prescriptions is high.

Role of Atypical Pathogens and the Antibiotic Prescription Pattern in Acute Bronchitis: A Multicenter Study in Korea

The role of atypical bacteria and the effect of antibiotic treatments in acute bronchitis are still not clear. This study was conducted at 22 hospitals (17 primary care clinics and 5 university hospitals) in Korea. Outpatients (aged > or = 18 yr) who had an acute illness with a new cough and sputum (< or = 30 days) were enrolled in 2013. Multiplex real-time polymerase chain reaction (RT-PCR) was used to detect five atypical bacteria. A total of 435 patients were diagnosed as having acute bronchitis (vs. probable pneumonia, n = 75), and 1.8% (n = 8) were positive for atypical pathogens (Bordetella pertussis, n = 3; B. parapertussis, n = 0; Mycoplasma pneumoniae, n = 1; Chlamydophila pneumoniae, n = 3; Legionella pneumophila, n = 1). Among clinical symptoms and signs, only post-tussive vomiting was more frequent in patients with atypical pathogens than those without (P = 0.024). In all, 72.2% of the enrolled patients received antibiotic treatment at their first visits, and beta-lactams (29.4%) and quinolones (20.5%) were the most commonly prescribed agents. In conclusion, our study demonstrates that the incidence of atypical pathogens is low in patients with acute bronchitis, and the rate of antibiotic prescriptions is high.

A cost-effective 25-Gb/s EML TOSA using all-in-one FPCB wiring and metal optical bench.

We present a cost-effective 25-Gb/s electro-absorption modulator integrated laser (EML) transmitter optical sub-assembly (TOSA) using all-in-one flexible printed circuit board (FPCB) wiring and a metal optical bench (MOB). For a low cost and high bandwidth TOSA, internal and external wirings and feed-through of the TOSA to transmit radio-frequency (RF) signal are configured all-in-one using the FPCB. The FPCB is extended from an exterior of the TOSA package up to an EML chip inside the package through the slit formed on a rear sidewall of the package and die-bonded on the MOB. The EML TOSA shows a modulated output power of more than 3.5 dBm and a clear eye pattern with a dynamic extinction ratio of ~8.4 dB at a data rate of 25.78 Gb/s.

N × N polymer matrix switches using thermo-optic total-internal-reflection switch.

We have developed fully non-blocking optical matrix switches using a thermo-optic polymer 1 × 2 total-internal-reflection (TIR) switch as a unit switching element. The TIR switch consists of crossed multimode polymer waveguides and an offset heater electrode at the switching node. The fabricated 4 × 4 and 8 × 8 optical matrix switch chips show excellent switching performances. The insertion losses are less than 2.5 and 4.5 dB for the 4 × 4 and 8 × 8 matrix switches, respectively, and their switching isolations during a turned-off state are higher than 38 dB. The switching time is about 3 ms, and the power consumption for each switching element is below 30 mW. Compact integration of the 4 × 4 and 8 × 8 switch chips is achieved at sizes of 25 mm × 4.25 mm, and 42.4 mm × 5 mm, respectively, through an optimization of the waveguide and heater geometries.