Comparative Analysis of Thoracic Rotation Exercises: Range of Motion Improvement in Standing and Quadruped Variants.

There have been few investigations into the effectiveness of thoracic spine exercises for improving thoracic range of motion (ROM) in any plane. This study assessed the effectiveness of two thoracic spine exercises: one in the quadruped position and one in the thoracic standing position. We determined how these exercises affect thoracic spine mobility ROM over a 2-week intervention period. Thirty-nine healthy participants were enrolled and assigned to a Quadruped Thoracic Rotation group (n=17 participants: 9 females and 8 males) or Flamenco Thoracic Spine Rotation group (n=22: 14 females and 8 males). All participants were administered a KOJI AWARENESSTM screening test, and the initial thoracic spine ROM before intervention exercise was measured in a laboratory setting. Quadruped Thoracic Rotation was performed as the quadruped exercise and Flamenco Thoracic Spine Rotation as the standing exercise. The KOJI AWARENESSTM thoracic spine test and ROM were evaluated on the day after the first exercise session and again after the program. Despite their different approaches to thoracic mobility, the quadruped exercise and standing exercise achieved equivalent improvement in thoracic ROM after 2 weeks. Practitioners have a range of exercise options for enhancing thoracic mobility based on their environmental or task-specific needs.

The Japanese version of the anterior cruciate ligament-return to sport after injury (ACL-RSI) scale has acceptable validity and reliability.

PURPOSE: The anterior cruciate ligament-return to sports after injury (ACL-RSI) scale assesses the psychological impact of returning to sports (also referred to as psychological readiness) after ACL reconstruction. The aim of this study was to evaluate important measurement properties of the Japanese version of ACL-RSI scale. METHODS: Ninety-three participants who underwent ACL reconstruction filled out the Japanese version of ACL-RSI scale, the Tampa scale for kinesiophobia (TSK), the International Knee Documentation Committee-Subjective Knee Form (IKDC-SKF), and Knee injury and Osteoarthritis Outcome Score (KOOS). To assess test re-test reliability, 50 of the 93 participants re-answered the Japanese version of ACL-RSI scale within 10 days. Floor and ceiling effects, internal consistency, construct validity, and reliability of the Japanese version of ACL-RSI scale were analysed. RESULTS: There were no floor and ceiling effects. The Japanese version of ACL-RSI scale showed good internal consistency (Cronbach's alpha = 0.912). It was positively correlated with total points of IKDC-SKF and the Lysholm score, and with the all sub-categories of the KOOS, and it was negatively correlated with the TSK. Reliability of the Japanese version of ACL-RSI scale was satisfactory. CONCLUSION: The Japanese version of ACL-RSI scale has acceptable measurement properties. It can be a useful for evaluation of psychological readiness for return to sports in Japanese athletes who undergo primary ACL reconstruction. Information provided by the Japanese version of the ACL-RSI scale may also help to identify athletes who find return to sport a challenge, and guide conversations regarding treatment and rehabilitation plans. LEVEL OF EVIDENCE: II.

Two new species of dicyemid mesozoans (Dicyemida: Dicyemidae) from Octopus maya Voss & Solis-Ramirez (Octopodidae) off Yucatan, Mexico.

Two new dicyemid species are described from the endemic cephalopod Octopus maya Voss & Solis-Ramirez collected off Yucatan, Mexico. The renal sacs of 40 juvenile and adult octopuses from four localities were examined. Dicyema hochbergi n. sp. is a medium-sized species that reaches 2,245 µm in length. The vermiform stages consist of 18-24 peripheral cells, a conical calotte and the extension of the axial cell between the base and middle of the metapolar cells. Infusoriform embryos consist of 39 cells with urn cell containing one germinal cell, two nuclei and solid refringent bodies. Dicyema mexcayae n. sp. is a relatively small species that reaches 1,114 µm in length. The vermiform stages are constituted by 14-16 peripheral cells, an elongate calotte and the axial cell extending forward to the middle of the metapolar cells. The infusoriform embryos consist of 37 cells, two solid refringent bodies and urn cells with two nuclei each. The present study represents the first description of a dicyemid species from O. maya and increases the number of described species from Mexican waters to 11.

Redescription of Dicyemennea eledones (Wagener, 1857) (Phylum Dicyemida) from Eledone cirrhosa (Lamarck, 1798) (Mollusca: Cephalopoda: Octopoda).

Dicyemids are common parasites found in the kidneys of many cephalopods. Species identification previously relied on old species descriptions containing considerable confusions, casting doubt on taxonomy and identification. Detailed morphological description and genotyping of all developmental stages are required for an exact taxonomy. To this end, we undertook the redescription of the dicyemid Dicyemennea eledones (Wagener, 1857), infecting the cephalopod Eledone cirrhosa (Lamarck). Samples were collected off Concarneau in the Bay of Biscay, France, and off La Goulette in the Gulf of Tunis, Tunisia. Dicyemennea eledones is a large species, with adults reaching c.7,000 µm in length. The vermiform stages are characterised by having 23 peripheral cells, a conical calotte and an axial cell that extends to the base of the propolar cells. An anterior abortive axial cell is present in vermiform embryos. Infusoriform embryos consist of 37 cells; a single nucleus is present in each urn cell and the refringent bodies, which were not always seen, are possibly liquid. For the first time, an 18S rDNA sequence is generated for D. eledones, illustrating genetic differences with the other dicyemid 18S rDNA sequences available in databases. This sequence can now be used for D. eledones barcoding, making the identification of the species easier and more reliable.

HOST SWITCHING IN DICYEMIDS (PHYLUM DICYEMIDA).

Dicyemids (phylum Dicyemida) are the most common and most characteristic endosymbionts in the renal sacs of benthic cephalopod molluscs: octopuses and cuttlefishes. Typically, 2 or 3 dicyemid species are found in a single specimen of the host, and most dicyemids have high host specificity. Host-specific parasites are restricted to a limited range of host species by ecological barriers that impede dispersal and successful establishment; therefore, phylogenies of interacting groups are often congruent due to repeated co-speciation. Most frequently, however, host and parasite phylogenies are not congruent, which can be explained by processes such as host switching and other macro-evolutionary events. Here, the history of dicyemids and their host cephalopod associations were studied by comparing their phylogenies. Dicyemid species were collected from 8 decapodiform species and 12 octopodiform species in Japanese waters. Using whole mitochondrial cytochrome c oxidase subunit 1 (COI) sequences, a phylogeny of 37 dicyemid species, including 4 genera representing the family Dicyemidae, was reconstructed. Phylogenetic trees derived from analyses of COI genes consistently suggested that dicyemid species should be separated into 3 major clades and that the most common genera, Dicyema and Dicyemennea, are not monophyletic. Thus, morphological classification does not reflect the phylogenetic relationships of these 2 genera. Divergence (speciation) of dicyemid species seems to have occurred within a single host species. Possible host-switching events may have occurred between the Octopodiformes and Decapodiformes or within the Octopodiformes or the Decapodiformes. Therefore, the mechanism of dicyemid speciation may be a mixture of host switching and intra-host speciation. This is the first study in which the process of dicyemid diversification involving cephalopod hosts has been evaluated with a large number of dicyemid species and genera.

Predictive Value of the KOJI AWARENESS Self-Evaluation System for Running Injuries in Elite Male Long-Distance Runners: A Prospective Cohort Study.

Background: The KOJI AWARENESS (KA) test is a practical self-evaluation tool that assesses body movements and may help develop individual conditioning plans to improve movement function. However, the association between preseason KA scores and in-season injury occurrence remains unexplored. Purpose: To investigate whether the KA self-screening test score can predict running-related injuries in elite long-distance runners. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 47 elite college male long-distance runners (age, 18-22 years) were enrolled in this study in June 2022. The participants underwent the KA self-screening test to assess preseason upper limb, core, and lower limb function. Running-related injuries with a training time loss of >3 weeks were tracked for 6 months during the season. The participants were divided into injury and noninjury groups, and between-group comparisons and receiver operating characteristic (ROC) curve analysis were used to determine the association between the KA scores and the injury incidence. Chi-square tests and risk ratios were calculated based on the cutoff value- and injury-based grouping. Results: Among the runners, 10 (21.3%) sustained an injury. There were no significant differences in the demographic characteristics between the injury and noninjury groups. The injury group had significantly lower KA scores than the noninjury group (median, 44.5 [interquartile range, 43-46.8] vs median, 48 [interquartile range, 46-50], respectively; P = .009). The ROC curve analysis determined a cutoff value of 46.5 points (sensitivity, 73%; specificity, 63.6%), indicating that the KA scores exhibited a relatively high predictive value for running-related injuries (area under the ROC curve, 0.764 [95% CI, 0.600-0.930]). The risk ratio for group division based on the cutoff value was 2.590 (95% CI, 1.329-5.047). Conclusion: These findings demonstrated that the KA test is an effective self-screening tool for predicting the risk of running-related injuries in elite male long-distance runners.

Effects of differences in femoral anteversion and hip flexion angle on hip abductor muscles activity during clam exercise in females.

This study aimed to determine differences in the hip abductor muscle activity during clam exercise at different hip flexion and femoral anteversion angles. Thirty healthy females were divided into two groups based on the femoral anteversion angle: the excessive femoral anteversion group and the normal group. Clam exercise was performed at three different hip flexion angles (60°, 45°, and 30°). Tensor fascia latae, gluteus medius, and superior portion of gluteus maximus activities were measured during the exercise, and the results were normalized to the activity during maximum voluntary isometric contraction to calculate the gluteal-to-tensor fascia latae muscle activation index. The superior portion of gluteus maximus activities at a hip flexion of 60° and 45° were greater than that at 30°. The excessive femoral anteversion group had a lower gluteal-to-tensor fascia latae muscle activation index than the normal group; the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° was higher than that at 45°, and the gluteal-to-tensor fascia latae muscle activation index for hip flexion at 60° and 45° were higher than that at 30°. Therefore, the femoral anteversion angle and hip joint position were related to the activity of the hip abductor muscles during clam exercise. These findings may provide a rationale for instructing exercises to maximize the activity of the hip abductor muscles in individuals with an excessive femoral anteversion angle.

Light weights are as effective as heavy weights for muscle activation in the Hammerobics exercise.

PURPOSE: We previously reported that a Hammerobics exercise using weights can enhance trunk and lower extremity muscles, some studies suggested that training effects could also be expected without heavy weights. If the muscle activity induced by Hammerobics swinging with a 'light plastic ball' equals or surpasses that of the isometric static squat and synchronized squat with a heavy ball, this training approach could alleviate joint strain, fostering an exercise regimen universally accessible across generations, benefit for workouts sports and rehabilitation. METHODS: Fifteen healthy men participated in this study. By using surface electromyography, muscle activities for the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, rectus femoris, biceps femoris long head, semitendinosus, gluteus maximus, multifidus, and internal oblique muscles were measured during a light Hammerobics synchronized squat (HSS-light), Hammerobics synchronized squat, and conventional isometric squat, and statistically compared. RESULTS: The front-to-back tibialis anterior activity of HSS-light was significantly higher than that of conventional isometric squat. The activities of all other muscles, except for the multifidus, were not significantly different between these exercises in the front-to-back and back-to-front phases. Compared to the Hammerobics synchronized squat, the light Hammerobics synchronized squat showed no differences in front-to-back tibialis anterior, rectus femoris, biceps femoris long head, and internal oblique activities and back-to-front abductor hallucis, tibialis anterior, rectus femoris, and internal oblique activities. CONCLUSION: The HSS-light could stimulate muscles to the same level as the conventional isometric squat without weight bearing. While the HSS-light was less effective than the Hammerobics synchronized squat, there was no significant difference in internal oblique, rectus femoris, and tibialis anterior activities between these exercises. Hence, the HSS-light is an exercise method that can be viable approach to promoting accessible workouts sports and rehabilitation.

Exploring age-related changes in motor function: insights from the peak decline found in Koji Awareness screening test.

The KOJI AWARENESS (KA) screening test assesses motor function in humans. We aimed to analyze the correlation between age and KA screening scores and to identify the specific age at which a significant decline occurs. A total of 793 healthy participants (234 females) were interviewed for basic information on age and sex and completed the KA screening test. In addition to calculating the total score from the KA test, the scores were calculated for the neck-scapula-upper extremity-complex (NSU), trunk, and lower extremity (LE) segments. Spearman's rank correlation coefficient was used to assess the validity of the test. Additionally, Bayesian linear regression was employed to estimate the change point in KA scores, facilitating the identification of a critical age associated with a notable decline in motor function. KA screening total and separate body segment scores were negatively correlated with age in both gender (for female and male, KA total score, ρ = - 0.443, ρ = - 0.344; NSU segment, ρ = - 0.431, ρ = - 0.427; trunk segment, ρ = - 0.210, ρ = - 0.473; LE segment: ρ = - 0.43, ρ = - 0.507). Furthermore, a change-point analysis using linear regression analysis showed that KA screening total scores declined sharply at the age of 49.1(95% credible interval: 37.503, 68.366). The result show that total KA scores decrease - 0.196 (95% credible interval: - 0.335, - 0.049) for every 1 year of age increase, and for ages over 49.1, total KA scores additionally decrease - 0.255 (95% credible interval: - 0.485, - 0.054) for every 1 year of age increase. In the NSU segment, females showed a more rapid decline than males from the age of 50 years. KA screening test total scores declined sharply at the age of 49.1. These results may be useful in setting treatment goals, exercise, and lifestyle programs for age-related decline in motor function.

Two new Japanese species of Gastrotricha (Chaetonotida, Chaetonotidae, Lepidodermella and Dichaeturidae, Dichaetura), with Comments on the Diversity of Gastrotrichs in Rice Paddies.

Two new species of freshwater gastrotrichs are described from rice paddies in Otsu, Shiga, Japan. Lepidodermella acantholepida n. sp. is a medium sized species attaining a length of 145 microum, scales are flattened ovals and similar to those of L. squamata except that two dorsal scales near the furca have a claw-like spine. Dichaeturafilispina n. sp. is a medium sized species attaining a length of 185 microm, characterized by a thin, fiber-like spine, a spined furca with a constriction near its base and an elongate body. A total of 44 species (seven genera) including two new species were found in the rice paddies. The diversity of rice paddy gastrotrichs is briefly discussed.

ESCAPE PROCESSES IN EMBRYOS OF DICYEMIDS (PHYLUM DICYEMIDA).

Dicyemid mesozoans usually consist of 10 to 40 cells. They are characterized by 2 distinct embryos, vermiform and infusoriform, that develop within the axial cell of the adult. The means of escape of each embryo from the parent body was studied in Dicyema japonicum and Dicyema misakiense, parasites of Octopus sinensis. There were no differences in means of escape between species or embryo type, apparently due to morphological constraints whereby the parents (nematogen or rhombogen) share a similar body organization. Escapes were effected through the gap between adjacent peripheral cells of the adult, rupturing the axial cell membrane and the membrane that envelopes the embryo. After the embryo escaped, the path was closed by the enveloping membrane left behind by the embryo. Vermiform embryos can escape from any region of the body, although more embryos were observed to escape from anterior regions than from posterior regions. Infusoriform embryos escaped from both anterior and posterior regions in the axial cell, with more embryos observed to escape from the posterior regions. The different escape regions for the 2 types of embryo are presumably related to the adult body plan lacking a genital opening, so each different type of embryo has its appropriate site of escape.

The effectiveness of corrective exercises on the KOJI AWARENESS score and activity-related pain intensity.

BACKGROUND: The KOJI AWARENESS� screening test is a self-administered screening tool for assessment of mobility, stability, and strength. It provides corrective exercises corresponding to the individual's answers to the KOJI AWARENESS� test questions. However, there is no evidence of the effectiveness of corrective exercises in improving KOJI AWARENESS� screening test scores and activity-related pain. METHODS: Twenty-six healthy subjects (11 female and 15 male ; age 20?50 years) were selected for participation. In a controlled laboratory setting, subjects were administered the KOJI AWARENESS� test and were provided with individualized exercise programs based on the results of this first test. KOJI AWARENESS� results were checked on the first day immediately after the first exercise session, and then again after the two-week program. Pain intensity was also assessed during daily training using a numerical rating scale. RESULTS: Compared to pre-intervention, KOJI AWARENESS� scores were significantly higher immediately after the first corrective exercise session and after 2 weeks of intervention (p<0.001). Moreover, pain intensity was significantly lower after 2 weeks of intervention (p<0.001). CONCLUSIONS: Individualized KOJI AWARENESS� corrective exercises were effective immediately on the first day and also after the two-week program in improving the KOJI AWARENESS� score and reducing pain intensity during daily training. J. Med. Invest. 70 : 208-212, February, 2023.

Mitochondrial genome of a Japanese placozoan.

Placozoans are marine invertebrates found in tropical and subtropical waters. Their body plan is among the simplest of free-living animals. The present study determined the mitochondrial genome sequence of a placozoan collected on the coast of Shirahama, Wakayama, Honshu, Japan, and compared it with those of Trichoplax adhaerens from the Red Sea and of three strains from the Caribbean Sea. The sequences of mitochondrial respiratory chain of the Japanese placozoan genes are very similar to those of the BZ49 strain from the Caribbean Sea. However, there are distinct differences in gene arrangement, such as the location of two open reading frames. This Japanese placozoan is therefore distinguishable from the other strains. Based on current knowledge of placozoan 16S diversity our 'Shirahama' strain most likely represents the H15 lineage, known from the Philippines. In the mitochondrial genome of placozoans, substitution rates are slower than in bilaterians, whereas the rate of rearrangements is faster.

Differences in trunk and lower extremity muscle activity during squatting exercise with and without hammer swing.

Perturbation exercises enhance lower limb and trunk muscles, and adding swing perturbation while loading during exercise might improve muscle activation or strength. This study aimed to check variations in trunk and lower limb muscle activity during conventional isometric squats, and whether it will change with or without swing using the Hammerobics-synchronized squat method. Twelve healthy men participated in this study. Activities for the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, rectus femoris, biceps femoris long head, semitendinosus, gluteus maximus, multifidus, and internal oblique muscles were measured using surface electromyography during a Hammerobics-synchronized squat and conventional isometric squat. Muscle activities were statistically compared between squat methods. Hammerobics-synchronized squats significantly activated the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, semitendinosus, and multifidus muscles, in both phases, compared with the conventional isometric squats. The Hammerobics-synchronized squat exercise can be considered for trunk and foot stability exercise.

Validity of the KOJI AWARENESS self-screening test for body movement and comparison with functional movement screening.

OBJECTIVE: This study aimed to validate the KOJI AWARENESS™, a self-screening movement test, and compare it with the Functional Movement Screen (FMS). METHODS: Fifty-seven healthy participants completed the KOJI AWARENESS™ and functional movement screening. Pearson's correlation coefficients were used to assess the validity of the test. Subsequently, partial correlation analysis was used to determine the associations between age, sex, body mass index, and sports level as control variables and motor function. RESULTS: Correlation and partial correlation analyses showed a strong positive correlation between the functional movement screening and the KOJI AWARENESS™ scores. CONCLUSION: This study found that the KOJI AWARENESS™ test is valid and comparable to functional movement screening. It can be used for self-screening of movement.

The relationship between movement self-screening scores and pain intensity during daily training.

Background : Various musculoskeletal screening and functional performance tests are used to evaluate physical condition. However, validated analysis tools that can identify gaps in pain knowledge during athletes' daily training are lacking. This study aimed to investigate the relationship between pain intensity in athletes during their daily training and the KOJI AWARENESS™ test in order to determine whether body dysfunction is related to pain among athletes. Methods : This cross-sectional study was conducted in a fitness center at the authors' affiliated institution. Thirty-five athletes (17 women and 18 men) aged 20-40 years were selected for study participation. KOJI AWARENESS™ self-evaluated test scores and pain intensity during daily training, as assessed on the numerical rating scale (NRS), were recorded. Results : The KOJI AWARENESS™ score showed a strong negative correlation with the NRS score for pain intensity during daily training (r = -0.640, P < 0.001). There was a significant negative correlation between KOJI AWARENESS™ and NRS scores, even when body mass index, sex, and age were entered as control variables. Conclusions : KOJI AWARENESS™ was highly accurate in detecting pain in athletes during their training. J. Med. Invest. 69 : 204-216, August, 2022.

Construct Validity and Reliability of the Japanese Version of the Lumbar Stiffness Disability Index.

STUDY DESIGN: Outcome study to determine the construct validity and reliability of the Japanese version of the Lumbar Stiffness Disability Index. OBJECTIVE: The aim of this study was to evaluate the psychometric measurement properties of the Japanese version of the Lumbar Stiffness Disability Index (J-LSDI) following lumbar spinal surgery in order to assess its construct validity and reliability. SUMMARY OF BACKGROUND DATA: The LSDI was designed and validated as a tool to assess functional impacts of lumbar spine stiffness and diminished spinal flexibility. A Japanese version has been developed, but its construct validity and reliability have not been evaluated. METHODS: A Pearson correlation coefficient was calculated using flexion and extension range of motion, Oswestry Disability Index (ODI) and Tampa Scale for Kinesiophobia (TSK) as external standards to evaluate construct validity. An intraclass correlation coefficient (ICC) and a Bland-Altman analysis were used to evaluate test-retest reliability. RESULTS: A total of 244 patients following lumbar spinal surgery participated in the study. Fifty one of the 244 patients participated in the reliability study. The ICC of the J-LSDI for test-retest reliability was 0.89 (95% confidence interval, 0.79-0.93). There was no systematic error found in the results of the Bland-Altman analysis. One hundred ninety-three of the 244 patients participated in the validity study. There were significant correlations between the J-LSDI and trunk flexion range of motion (r = -0.66), extension (r = -0.51), ODI (r = 0.62), and TSK (r = 0.38). CONCLUSION: The construct validity and reliability of the Japanese version of the LSDI were confirmed. The J-LSDI can be used to evaluate lumbar stiffness and associated disability in Japanese patients following lumbar spinal surgery.Level of Evidence: 2.

Squid vascular endothelial growth factor receptor: a shared molecular signature in the convergent evolution of closed circulatory systems.

The highly specialized cephalopod cardiovascular system has long been considered a valuable model for understanding the evolution of circulatory systems. Despite the number of studies devoted to this topic, the developmental regulatory mechanisms remain largely unexplored. Here, we focus on the vascular endothelial growth factor receptor (VEGFR). This factor is known to mediate levels of endothelial growth factor that is involved in hematopoiesis and vasculogenesis including multichambered heart development in vertebrates. We found a squid VEGFR ortholog that is expressed in the developing blood vessels, notably in the sheet-like endothelial cells of the systemic and branchial hearts. The highly restricted localization of VEGFR in the vascular endothelial cells and its shared expression pattern in the developing hearts of cephalopods and vertebrates suggest a shared molecular signature of closed circulatory systems that has been independently elaborated during evolution.

Dicyema sphyrocephalum (Phylum Dicyemida: Dicyemidae) isolated from Korean common octopus Callistoctopus minor in Korea.

BACKGROUND: Dicyemids are parasites found in the renal sac of cephalopods. The first species of dicyemid was found from kidneys of the Korean common octopus Callistoctopus minor. OBJECTIVES: This study aimed to identify the dicyemid and investigate the effect on renal sac of host. METHODS: In this study, we compared the morphological characteristics of isolate to dicyemids (Dicyema sphyrocephalum, Dicyema clavatum, and Dicyema dolichocephalum) reported from C. minor in Japan. We compared the 18S ribosomal RNA (rDNA) and cytochrome c oxidase subunit I (COI) sequences of isolate to the sequences of D. shyrocephalum and D. clavatum. The infected octopuses renal tissues were histologically compared with the tissues of uninfected individuals. RESULTS: The morphological characteristic of this isolated species corresponds to D. sphyrocephalum. The sequences similarities of 18S rDNA and COI gene of isolate are 99.7% and 98.1% with D. sphyrocephalum. We observed morphological changes in the epithelia folds of kidney at the dicyemids attached areas. CONCLUSIONS: The present study identified the isolate as D. sphyrocephalum and this is the first report of dicyemid species from Republic of Korea. Further studies on the effects of dicyemids on growth and health status of cephalopods will be needed.

Molecular markers comparing the extremely simple body plan of dicyemids to that of lophotrochozoans: insight from the expression patterns of Hox, Otx, and brachyury.

Because of their extremely simple body plan, dicyemids have long been the subject of phylogenetic controversy, regarding whether their body plan reflects their primitiveness or a degeneration from complex metazoans. Several studies have argued that the simple body plan of dicyemids are likely secondarily derived from higher lophotrochozoan animals, as a result of their endoparasitic, or endosymbiotic, lifestyle in the cephalopod kidney. To clarify the evolution of their simple body plan, we investigated the developmental expression patterns of three important regulatory genes, the central type Hox gene (DoxC), otx, and brachyury homologs in the dicyemid mesozoa, Dicyema orientale. DoxC was expressed in the trunk and tail of the asexually developing vermiform embryo, with clear anterior boundaries. Do-otx was expressed in the vegetal pole cells of the developing infusoriform embryos, suggesting that the invagination in infusoriform embryo is homologous to the gastrulation of other metazoans. Do-bra is expressed in the presumptive ventral cells, which are ventral to the opening of the urn cavity. The expression of Do-bra suggests that the urn cavity opening of the infusoriform embryo is comparable to the stomodium of trochophore larvae. These gene expression patterns provide molecular clues to trace the evolutionary history of degeneration in the dicyemid embryogenesis and life cycle from those of ancestral lophotrochozoan animals.