Vitrified before and after genome editing via electroporation

BACKGROUND

Cryopreservation of bovine zygotes allows for a flexible schedule of genome editing via electroporation. However, vitrification-induced cell membrane damage may not only affect embryonic development but also genome mutation.

OBJECTIVE

To investigate the effects of vitrification of zygotes before and after electroporation treatments on the development and genome mutation of bovine presumptive zygotes.

MATERIALS AND METHODS

In vitro-derived bovine zygotes were electroporated with the CRISPR/Cas9 system immediately (Vitrified-EP) or 2 h after incubation (Vitrified-2h-EP) following vitrification and warming, or electroporated before vitrification (EP-vitrified).

RESULTS

The development rates of vitrified-warmed zygotes were significantly lower (p < 0.05) than those of control zygotes that were not vitrified. Moreover, no differences were observed in the mutation rates and mutation efficiency of the blastocysts resulting from electroporated zygotes, irrespective of the timing of electroporation treatment.

CONCLUSION

Our results suggest that vitrification before and after electroporation treatments does not affect the genome editing of zygotes.

Development of an apparatus for evaluating the visual and olfactory discrimination ability of cattle under controlled target visibility

Ungulates visually and olfactorily discriminating between vegetation patches in grasslands often encounter restriction of target visibility due to light intensity changes; however, little is known about their performance in such a context. We developed and tested an apparatus for evaluating the visual and olfactory discrimination ability of cattle under controlled target visibility, focusing on the discrimination at a short distance. The apparatus was designed to contain a discrimination target under a sliding cover of variable light transmission levels and behind a vent of a fixed size and aperture so as to control the visibility of the target (14-100% restrictions) while ensuring a constant level of odor. Twelve Japanese Black cows were allowed to choose between two apparatuses presenting a pair of targets: green forage versus empty, green forage versus dead forage, or green forage versus green-dead mixture. Cows rapidly learned to slide open the cover to reach the selected target, consistently chose the green forage against the alternative except against the green-dead mixture under 100% visual restriction, and remembered the reaching procedure for at least 16 days. The results indicate the usefulness of the apparatus for assessing close visual and olfactory discrimination ability of cattle in detail.

Individual Monitoring of Behavior to Enhance Productivity and Welfare of Animals in Small-Scale Intensive Cattle Grazing Systems

To enhance productivity and welfare of individual animals maintained as a group, management based on individual behavioral tendencies is essential, which requires individual monitoring of animal behavior. Several behavior monitoring systems are currently available to livestock producers. The data obtained from these systems are analyzed to detect significantly high or low frequencies or intensities of behavior associated with estrus, calving and poor health conditions based on thresholds or past trends of the monitored individual. However, because behavior under grazing is more complex and changeable than under confinement, behavioral symptoms are more difficult to detect, and on-farm monitoring of individual animal behavior has been less validated and utilized in grazing systems. Nevertheless, individual monitoring of all animals in a herd is more feasible and cost-effective in small-scale intensive grazing systems because these systems pursue high productivity at the individual level with smaller herd size than large-scale extensive systems. Individually tailored management to enhance productivity and welfare will be possible by focusing on inter-individual differences in behavior within a herd. Behavior of an individual can be analyzed and understood in more detail by comparing it with those of the herd mates. Higher or lower levels of specific activities than the other animals can be associated with health disorders, temporal changes in physiological states, or productivity- or welfare-related traits. More sensitive monitoring and detection of behavioral responses of individuals to changes in nutritional, physical and social environments will lead to more efficient and welfare-conscious management that better meets the needs of individuals.

Development of radioiodinated pyrimidinopyridone derivatives as targeted imaging probes of activated p38α for single photon emission computed tomography

OBJECTIVE

p38α, a member of the mitogen-activated protein kinase superfamily, is ubiquitously expressed in a variety of mammalian cells. Activated p38α induces inflammatory responses to external stimuli, suggesting that non-invasive detection of activated p38α would be valuable for diagnosing inflammatory diseases. For this purpose, we designed radiolabeled compounds [¹²³I]2-IR and [¹²³I]4-IR based on a potent p38α selective inhibitor R1487 for use with single photon emission computed tomography (SPECT). In this study, we used ¹²⁵I instead of ¹²³I due to its more usable radiochemical properties, synthesized [¹²⁵I]2-IR and [¹²⁵I]4-IR, and evaluated their effectiveness as activated p38α imaging probes.

METHODS

[¹²³I]2-IR and [¹²³I]4-IR were designed by introduction of a ¹²³I atom at the 2- or 4-ositions of the phenoxy ring, preserving the pyrimidinopyridone structure of R1487. We synthesized 2-IR and 4-IR via a 7-step process. The inhibitory potencies of 2-IR, 4-IR, and p38α inhibitors were measured using an ADP-Glo™ kinase assay system. Radioiodination of 2-IR and 4-IR was performed via an organotin-radioiodine exchange reaction using the corresponding tributyltin precursors. Biodistributions were evaluated by determining radioactivity in tissues of interest after intravenous administration of [¹²⁵I]2-IR and [¹²⁵I]4-IR in normal ddY mice and turpentine oil-induced inflammation model mice. In vivo inhibition study was also performed in inflammation model mice after intravenous administration of [¹²⁵I]4-IR with pretreatment of p38α inhibitors.

RESULTS

We synthesized 2-IR and 4-IR at total yields of 17.5% and 19.2%, respectively. 4-IR had higher p38α inhibitory potency than 2-IR; both compounds were significantly less potent than R1487. [¹²⁵I]2-IR and [¹²⁵I]4-IR were successfully obtained from tributyltin precursors with high radiochemical yield (> 65%), purity (> 97%), and molar activity (~ 81 GBq/µmol). [¹²⁵I]4-IR showed high radioactivity accumulation in the inflamed tissue (7.0 ± 1.2%D/g), rapid delivery throughout the body, and rapid blood clearance, resulting in a high inflammation-to-blood ratio (6.2 ± 0.4) and a high inflammation-to-muscle ratio (5.2 ± 1.3) at 30 min, while [¹²⁵I]2-IR showed low radioactivity accumulation in inflamed tissue over the experimental period. Further, radioactivity accumulation in inflamed tissue after [¹²⁵I]4-IR administration was significantly decreased by pretreatment with selective inhibitors.

CONCLUSIONS

[¹²³I]4-IR would be a promising imaging agent for detection of activated p38α.

Measurement of axial phase difference of density fluctuations owing to spontaneously excited waves by using microwave reflectometer on GAMMA 10/PDX

In the GAMMA 10/PDX tandem mirror, plasma with strong ion-temperature anisotropy is produced by using the ion cyclotron range of frequency waves. This anisotropy of ion temperature causes several Alfvén-Ion-Cyclotron (AIC) waves to spontaneously excite in the frequency range just below the ion cyclotron frequency. In addition, difference-frequency (DF) waves are excited in the radial inner region of the plasma by wave-wave coupling among the AIC waves. The radial density profiles were measured at multi-axial positions using a frequency-modulation reflectometer with an axial array of microwave antennas, and an axial variation of the density was found to be significant. In addition, a relative phase difference of the DF wave between axially separated two points was first obtained by finely choosing the probing frequency of the reflectometers with a maximum coherence used as a measure, indicating that the DF wave is a propagating wave, while the pump AIC waves are standing waves in the axial region of measurement.

SNPs from BCHE and DRD3 genes associated to cocaine abuse amongst violent individuals from Sao Paulo, Brazil

Violence and drug abuse are highly destructive phenomena found world-wide, especially in Brazil. They seem to rise proportionally to one another and possibly related. Additionally, genetics may also play a role in drug abuse. This study has focused on identifying the use of cocaine within postmortem cases arriving at the Institute of Legal Medicine of Sao Paulo as well as the presence of certain single nucleotide polymorphisms (SNPs) to better understand one's susceptibility to abuse the drug. Both hair and blood samples have been extracted through a simple methanol overnight incubation or a rapid dilute-and-shoot method, respectively. The samples were then analyzed using an UPLC-ESI-MS/MS and genotyped through RT-PCR. Statistical analyses were performed via SPSS software. From 105 postmortem cases, 53% and 51% of the cases shown to be positive for cocaine in hair and blood, respectively. Genetic wise, a significant difference has been observed for SNP rs4263329 from the BCHE gene with higher frequencies of the genotypes A/G and G/G seen in cocaine users (OR=8.91; 95%CI=1.58-50.21; p=0.01). Likewise, also SNP rs6280 from the DRD3 gene presented a significant association, with both genotypes T/C and C/C being more frequent in users (OR=4.96; 95% CI=1.07-23.02; p=0.04). To conclude, a rather high proportion of cocaine has been found, which may suggest a connotation between the use of the drug and risky/violent behaviors. Additionally, significant associations were also found within two SNPs related to cocaine use, however, due to several inherent limitations, these must be confirmed.

Relative importance of senses in forage discrimination by cattle depends on the sensory contrast between the discrimination targets: a preliminary study

The ability of ungulates to discriminate among vegetation patches depends largely on the senses of vision, olfaction, tactility, and gustation. However, little is known about how ungulates rely on the respective senses in response to varying patch characteristics. This study aimed to evaluate how relative importance of senses in patch discrimination by cattle is affected by the sensory contrast between the discrimination targets. Five Japanese Black cows were allowed to choose between two forage patches from a distance of about 1 m. Two combinations of forage patches were used: one was a pair of green and dead forages of bahiagrass (BG) with clear mutual contrast in appearance and odor, and the other was a pair of green forages of BG and cogongrass (CG) with visual and olfactory resemblance. Cows preferably located and ate the green BG as the first choice (Type 1), or as the second choice after touching (Type 2) or further biting (Type 3) the alternative in error. Overall, Type 1 accounted for a high above-chance proportion of 0.94 in the green BG vs. dead BG discrimination, indicating the primary importance of vision and olfaction. By contrast, in the green BG vs. green CG discrimination, Type 1 remained at the chance level of 0.55 with proportions of 0.17 for Type 2 and 0.28 for Type 3, indicating the primary importance of tactility on the muzzle and in the mouth. The context-specific importance of the four senses in patch discrimination represents an adaptive mechanism of animals foraging in grasslands.

Radioiodinated bicyclic RGD peptide for imaging integrin αvβ3 in cancers

Integrin α_vβ₃ is an effective marker of angiogenesis in cancer, and α_vβ₃-specific imaging can yield important details about this complex physiological process. We utilized the recently reported and highly α_vβ₃-specific peptide, bicyclic RGD (bcRGD), as the basic structure of an in vivo α_vβ₃ imaging probe, and synthesized a radioiodinated form of bcRGD, namely [¹²⁵I]bcRGD, with high radiochemical purity (>99%) and high molar activity (81 GBq/μmol). As expected, [¹²⁵I]bcRGD exhibited high selectivity for α_vβ₃ compared with α_vβ₅ and α₅β₁in vitro. [¹²⁵I]bcRGD showed significantly higher accumulation in U-87MG cells (1.6% dose/mg) with high expression of α_vβ₃ compared to A549 cells (0.3% dose/mg) with only moderate expression. Furthermore, 30 min after administration to tumor-bearing mice, [¹²⁵I]bcRGD showed significantly higher accumulation in U-87MG tumors (3.8% ID/g) than in A549 tumors (2.1% ID/g), and the radioactivity accumulation ratios of U-87MG tumor/blood and U-87MG tumor/muscle were 4.0 and 6.0, respectively. These results highlight the promising properties of [^123/125I]bcRGD for use as an in vivo α_vβ₃ imaging probe, as well as the utility of bcRGD as a basic structure of molecular probes for both imaging and therapeutic applications. bcRGD may exhibit broad use in future theranostics applications targeting integrin α_vβ₃-related diseases.

Synthesis and evaluation of novel radioiodinated anthranilate derivatives for in vivo imaging of vascular endothelial growth factor receptor with single-photon emission computed tomography

OBJECTIVE

Angiogenesis facilitates tumor survival and promotes malignancy. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) tyrosine kinase (TK) signaling pathway is a key factor mediating angiogenesis, suggesting that this pathway may be a target for diagnosis and therapy. In this study, we aimed to develop small molecule radioiodinated probes applicable for in vivo VEGFR imaging considering the versatility and usefulness of single-photon emission computed tomography (SPECT).

METHODS

We designed and synthesized four radioiodinated anthranilate compounds (6a-d) based on the structure of an anticancer drug targeting VEGFR-TK. The inhibitory potencies of corresponding cold compounds 4a-d and in vitro stability of compounds 6a-d were assessed by cellular proliferation inhibition assays and radio thin-layer chromatography after incubation in neutral solution. In vivo biodistributions were evaluated by determining radioactivity in tissues of interest after intravenous injection of test compounds in tumor-bearing mice. In vitro and in vivo blocking experiments using a selective VEGFR-TK inhibitor and SPECT/computed tomography (CT) imaging were performed in tumor-bearing mice.

RESULTS

The radioiodinated compounds 6a-d were obtained with more than 68.0% radiochemical yield and more than 95% radiochemical purity. Because compounds 4a-d showed high inhibitory potencies and compounds 6c and 6d showed high in vitro stability, 6c ([¹²⁵I]m-NPAM) and 6d ([¹²⁵I]p-NPAM) were further evaluated. Analysis of the in vivo biodistribution revealed a tumor to blood radioactivity ratio of greater than 4 at 24 h after [¹²⁵I]p-NPAM administration. Accumulation of radioactivity in cultured tumor cells and tumor xenografts after [¹²⁵I]p-NPAM administration was significantly blocked by inhibitor pretreatment. Tumors were clearly imaged at 24 h after [¹²⁵I]p-NPAM injection with SPECT/CT in comparison to that in inhibitor-pretreated tumor-bearing mice.

CONCLUSION

[¹²⁵I]p-NPAM may have potential applications as a lead compound for future development of a clinically usable VEGFR imaging probe for SPECT.

In vitro Development of Zona Pellucida-free Porcine Zygotes Cultured Individually after Vitrification

BACKGROUND

Cryopreservation of zona pellucida (ZP)-free embryos provides more options for somatic cell nuclear transfer, particularly during handmade cloning.

OBJECTIVE

This study investigated whether the removal of the ZP affects the development of porcine zygotes after vitrification and warming.

MATERIALS AND METHODS

We determined the appropriate volume of the corresponding medium for the individual culture of ZP-intact and -free embryos and evaluated the protection effect of ZP during cryopreservation on the resulting development of the vitrified-warmed zygotes.

RESULTS

The volume of culture medium influenced the development of ZP-intact zygotes, and a volume of 15 µL was most suitable for their development. However, the volume of culture medium did not modify the development of ZP-free zygotes. The removal of the ZP before vitrification did not adversely affect embryonic development or quality of the resulting blastocysts.

CONCLUSION

Our results suggest that the removal of the ZP does not cause detrimental effects to the development of vitrified-warmed zygotes.

Development of a p38α-selective radioactive probe for qualitative diagnosis of cancer using SPECT

OBJECTIVE

p38 mitogen-activated protein (MAP) kinase (p38α) has drawn attention as a new target molecule for the treatment and diagnosis of cancer, and its overexpression and activation have been reported in various types of cancer. In this study, a single photon emission computed tomography (SPECT) imaging probe of p38α was developed to noninvasively image p38α activity for effective qualitative diagnosis of cancer.

METHODS

Pyrrolepyridine derivatives, m-YTM and p-YTM, were designed and synthesized based on the structure of the p38α-selective inhibitor. Radioactive iodine-labeled m-YTM, [¹²⁵I]m-YTM, was synthesized because m-YTM greatly inhibited the phosphorylation of p38α upon examining the inhibitory effects of the compounds. After investigating the binding affinity of [¹²⁵I]m-YTM to the recombinant p38α, a saturation binding experiment using activated p38α and inactive p38α was performed to determine the binding site. Uptake of [¹²⁵I]m-YTM into various cancer cell lines was investigated, and the pharmacokinetics was evaluated using tumor-bearing mice.

RESULTS

The inhibitory activity of m-YTM was approximately 13 times higher than that of SB203580, a p38α-selective inhibitor. The binding site of [¹²⁵I]m-YTM was estimated to be the p38α activating site, similar to that of SB203580, because the [¹²⁵I]m-YTM bound strongly to both activated p38α and inactive p38α. Various different cancer cells incorporated [¹²⁵I]m-YTM; however, its accumulation was significantly reduced by treatment with SB203580. Pharmacokinetics study of [¹²⁵I]m-YTM in B-16 tumor-bearing mice was examined which revealed high accumulation of radioactivity in tumor tissues. The ratios of radioactivity in the B-16 tumor to that in blood were 3.1 and 50 after 1 and 24 h, respectively. The ratio of radioactivity in the tumor to that in blood in the tumor-bearing mice generated using other cancer cell lines was also ≥ 1 at 1 h after the administration of the probe.

CONCLUSIONS

This study suggests that [¹²³I]m-YTM has potential as a p38α imaging probe effective for various cancer types.

Abstract P3-06-04: Clonal evolution of non-malignant proliferative lesions into breast cancers

[Introduction] Non-malignant proliferative lesions in the breast have been implicated in the development of invasive breast cancer. Previous studies showed that adjacent atypical proliferative lesions and breast cancers shared common genetic alterations, suggesting that these evolved from the same ancestral cell. However, the clonal structure of atypical proliferative lesions and their clonal dynamics during progression to cancer are poorly understood. In this study, we compared genetic profiles (with and without pathogenic germline mutations) of normal mammary ducts, non-malignant proliferative lesions, and cancer tissues from the same patients to illustrate the clonal evolution of cancer from a non-malignant epithelial cell.

[Methods] Multiple samples were collected from different proliferative lesions within the cancer-borne breast, including invasive cancers, using micro-dissection from formalin-fixed, paraffin-embedded surgical specimens. Somatic mutations and copy number alterations (CNAs) were then evaluated by whole exome sequencing.

[Results] We analyzed a total of 34 samples from 5 premenopausal females carrying estrogen receptor-positive cancers, where the samples were obtained from normal ducts (N = 6), non-atypical (N = 1) and atypical (N = 8) proliferative lesions, and non-invasive (N = 16) and invasive (N = 3) cancers. The number of somatic mutations per sample ranged from 1 to 276 and increased with disease progression, regardless of the germline mutation status. Two cases with bilateral cancers had a pathogenic germline mutation of either BRCA2 or TP53, where no somatic mutations or CNAs were shared by individual proliferative lesions, suggesting multifocal independent cancerous evolutions. By contrast, in the remaining three unilateral cases, no pathogenic germline mutations were detected, but all proliferative lesions, which were separated by a distance of 7-25 mm, shared one or more driver alterations, such as an AKT1 mutation (UID: KU01), concurrent 1q gain and 16q loss (der(1;16)) (UID: KU02), and a GATA3 mutation and der(1;16) (UID: KU03), while harboring private mutations and/or CNAs of their own. The phylogenetic analysis based on the number of shared mutations predicted an early origin of these founder mutations, which frequently predated decades before the onset of cancer.

[Conclusions] Our results suggest that early breast cancer development is shaped by the evolution of multiple precancerous clones. These clones are originated from a common ancestor that acquired a founder mutation long before the onset of cancer, followed by branching evolution of multiple clones that acquired additional driver mutations of their own, from which an invasive cancer ultimately develops. In hereditary cases, this process is thought to be substantially promoted multi-focally from within the entire breasts by a germline mutation shared by all mammary cells, frequently resulting in bilateral and/or multifocal breast cancers. Our findings provide unique insight into the early development of breast cancer.

Citation Format: Nishimura T, Yoshida K, Kawata Y, Takeuchi Y, Kakiuchi N, Shiozawa Y, Aoki K, Hirata M, Kataoka TR, Sakurai T, Baba S, Shiraishi Y, Chiba K, Takeuchi K, Haga H, Miyano S, Toi M, Ogawa S. Clonal evolution of non-malignant proliferative lesions into breast cancers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-04.

Novel object response in beef cattle grazing a pasture as a group

This study was conducted to investigate how cattle (Bos taurus) respond to objects presented for the first time and repeatedly in a stimulus-rich environment where they can freely graze and interact with conspecifics. Twenty-five Japanese Black cows were subjected to three repeats of a novel object test in which animals stocked on a pasture as a group were exposed to the same and different objects across the test repeats. Responses of cows towards the objects were quantified by both approach (entering within a 0.5-m distance of the object) and contact (physical touch with the object) measures as occurrence (1 or 0) and number of reactions and latency to the first reaction. Cows were consistent in the approach to the first-time objects (repeatability = 0.39-0.62, Kendall's W = 0.58, P <  0.05), but not in the approach to the repeatedly presented objects or in the contact with both types of objects (P > 0.05). Individuals which consistently approached the novel objects could be regarded as highly exploratory and/or bold in personality. Future work should consider novel object response in cattle across a range of contexts.

Effects of voltage strength during electroporation on the development and quality of in vitro-produced porcine embryos

This study was conducted to determine suitable conditions for an experimental method in which the CRISPR/Cas9 system is introduced into in vitro-produced porcine zygotes by electroporation. In the first experiment, when putative zygotes derived from in vitro fertilization (IVF) were electroporated by either unipolar or bipolar pulses, keeping the voltage, pulse duration and pulse number fixed at 30 V/mm, 1 msec and five repeats, respectively, the rate of blastocyst formation from zygotes electroporated by bipolar pulses decreased compared to zygotes electroporated by unipolar pulses. In the second experiment, the putative zygotes were electroporated by electroporation voltages ranging from 20 V/mm-40 V/mm with five 1-msec unipolar pulses. The rate of cleavage and blastocyst formation of zygotes electroporated at 40 V/mm was significantly lower (p < .05) than that of zygotes electroporated at less than 30 V/mm. Moreover, the apoptotic nuclei indices of blastocysts derived from zygotes electroporated by voltages greater than 30 V/mm significantly increased compared with those from zygotes electroporated by voltages less than 25 V/mm (p < .05). When zygotes were electroporated with Cas9 mRNA and single-guide RNA (sgRNA) targeting site in the FGF10 exon 3, the proportions of blastocysts with targeted genomic sequences were 7.7% (2/26) and 3.6% (1/28) in the embryos derived from zygotes electroporated at 25 V/mm and 30 V/mm, respectively. Our results indicate that electroporation at 25 V/mm may be an acceptable condition for introducing Cas9 mRNA and sgRNA into pig IVF zygotes under which the viability of the embryos is not significantly affected.

Effects of Antifreeze Protein Supplementation on the Development of Porcine Morulae Stored at Hypothermic Temperatures

BACKGROUND

Short-term storage is valuable method to reuse manipulated embryos.

OBJECTIVE

The present study evaluated the effects of antifreeze protein (AFP) supplementation on the quality and development of in vitro-produced porcine morulae after short-term storage (24 h).

MATERIALS AND METHODS

The morulae were stored with various concentrations of AFP type III for 24 h at 5, 15 and 25C.

RESULTS

Supplementation of AFP type III (1.0 microgram per mL) improved the developmental competence of embryos stored at 25C. The proportions of DNA-fragmented nuclei in the blastocysts did not differ between the embryos stored at 25C and the control embryos without storage treatment. However, the developmental competence of embryos stored at hypothermic temperatures decreased relative to that of the control embryos.

CONCLUSION

Supplementation of AFP type III (1.0 microgram per mL) maintained the quality of embryos stored at 25C, but did not have beneficial effects on the development of embryos stored at hypothermic temperatures.

Relationship Among Establishment Durations, Kin Relatedness, Aggressiveness, and Distance Between Populations of Eight Invasive Argentine Ant (Hymenoptera: Formicidae) Supercolonies in Japan

We investigated kin relatedness and kin-recognition abilities of the Argentine ant, Linepithema humile (Mayr), an invader from North America that has pervaded Japan for 20 yr, using genetic analyses and behavioral bioassays. From these data and interactions among factors, we formulated an eradication and management time-scale pattern diagram. Relatedness within a colony using microsatellite markers was effectively zero, whereas relatedness estimated by multilocus DNA fingerprinting markers was relatively high. Specifically, relatedness of recently invaded populations was estimated at nearly 0.3. From the results of behavioral bioassays on the invading populations of the Argentine ant, all colonies except the Kobe supercolonies did not show clearly aggressive behaviors toward workers belonging to other colonies, even when distantly located. Because they are critical factors for eradicating and managing invasive organisms, we assessed the relationships among kin relatedness using multilocus DNA fingerprinting and microsatellite markers, with aggressiveness, in 2011 and 2012, including the establishment durations, and distances among supercolonies. A generalized linear model (GLM) analysis, with establishment durations as an explanatory variable, strongly contributed to explaining estimated relatedness from the two methods. Specifically, models using kin relatedness for both multilocus DNA fingerprinting and microsatellite markers provided the strongest contribution to explaining the establishment durations. Within 3 yr after establishment in a native area, eradication is possible because of their low genetic diversity and small colony size. After 15 yr, eradication will be more difficult, but it is preferable to just monitor the impact for a nonnative ecosystem.

Multi-point measurement using two-channel reflectometer with antenna switching for study of high-frequency fluctuations in GAMMA 10

A two-channel microwave reflectometer system with fast microwave antenna switching capability was developed and applied to the GAMMA 10 tandem mirror device to study high-frequency small-amplitude fluctuations in a hot mirror plasma. The fast switching of the antennas is controlled using PIN diode switches, which offers the significant advantage of reducing the number of high-cost microwave components and digitizers with high bandwidths and large memory that are required to measure the spatiotemporal behavior of the high-frequency fluctuations. The use of two channels rather than one adds the important function of a simultaneous two-point measurement in either the radial direction or the direction of the antenna array to measure the phase profile of the fluctuations along with the normal amplitude profile. The density fluctuations measured using this system clearly showed the high-frequency coherent fluctuations that are associated with Alfvén-ion-cyclotron (AIC) waves in GAMMA 10. A correlation analysis applied to simultaneously measured density fluctuations showed that the phase component that was included in a reflected microwave provided both high coherence and a clear phase difference for the AIC waves, while the amplitude component showed neither significant coherence nor clear phase difference. The axial phase differences of the AIC waves measured inside the hot plasma confirmed the formation of a standing wave structure. The axial variation of the radial profiles was evaluated and a clear difference was found among the AIC waves for the first time, which would be a key to clarify the unknown boundary conditions of the AIC waves.

Quasiparticle Scattering off Defects and Possible Bound States in Charge-Ordered YBa_{2}Cu_{3}O_{y}

We report the NMR observation of a skewed distribution of ^{17}O Knight shifts when a magnetic field quenches superconductivity and induces long-range charge-density-wave (CDW) order in YBa_{2}Cu_{3}O_{y}. This distribution is explained by an inhomogeneous pattern of the local density of states N(E_{F}) arising from quasiparticle scattering off, yet unidentified, defects in the CDW state. We argue that the effect is most likely related to the formation of quasiparticle bound states, as is known to occur, under specific circumstances, in some metals and superconductors (but not in the CDW state, in general, except for very few cases in 1D materials). These observations should provide insight into the microscopic nature of the CDW, especially regarding the reconstructed band structure and the sensitivity to disorder.

Wireless Multichannel Neural Recording With a 128-Mbps UWB Transmitter for an Implantable Brain-Machine Interfaces

Simultaneous recordings of neural activity at large scale, in the long term and under bio-safety conditions, can provide essential data. These data can be used to advance the technology for brain-machine interfaces in clinical applications, and to understand brain function. For this purpose, we present a new multichannel neural recording system that can record up to 4096-channel (ch) electrocorticogram data by multiple connections of customized application-specific integrated circuits (ASICs). The ASIC includes 64-ch low-noise amplifiers, analog time-division multiplexers, and 12-bit successive approximation register ADCs. Recorded data sampled at a rate of 1 kS/s are multiplexed with time division via an integrated multiplex board, and in total 51.2 Mbps of raw data for 4096 ch are generated. This system has an ultra-wideband (UWB) wireless unit for transmitting the recorded neural signals. The ASICs, multiplex boards, and UWB transmitter unit are designed with the aim of implanting them. From preliminary experiments with a human body-equivalent liquid phantom, we confirmed 4096-ch UWB wireless data transmission at 128 Mbps for distances below 20 mm .

Multichannel neural recording with a 128 Mbps UWB wireless transmitter for implantable brain-machine interfaces

To realize a low-invasive and high accuracy BMI (Brain-machine interface) system, we have already developed a fully-implantable wireless BMI system which consists of ECoG neural electrode arrays, neural recording ASICs, a Wi-Fi based wireless data transmitter and a wireless power receiver with a rechargeable battery. For accurate estimation of movement intentions, it is important for a BMI system to have a large number of recording channels. In this paper, we report a new multi-channel BMI system which is able to record up to 4096-ch ECoG data by multiple connections of 64-ch ASICs and time division multiplexing of recorded data. This system has an ultra-wide-band (UWB) wireless unit for transmitting the recorded neural signals to outside the body. By preliminary experiments with a human body equivalent liquid phantom, we confirmed 4096-ch UWB wireless data transmission at 128 Mbps mode below 20 mm distance.