Comparison of Frontal and Transverse Plane Kinematics Related to Knee Injury in Novice Versus Experienced Female Runners.

Novice runners experience a higher incidence of knee injury than experienced runners, which may be related to aberrant frontal and transverse plane kinematics. However, differences in kinematics between novice and experienced runners have not been fully explored. For this study, 10 novice and 10 experienced female runners ran on a treadmill at 2.68 m/s. Ankle, knee, and hip joint angles during the stance phase were measured using a 3-dimensional motion capture system and modeled using cubic splines. Spline models were compared between groups using a generalized linear model (α = .05). Ninety-five percent confidence intervals of the difference between joint angles throughout stance were constructed to identify specific periods of stance where groups differed in joint position. Angle-angle diagrams of ankle and hip position in the frontal and transverse planes were constructed to depict joint coordination. Novice runners displayed less hip adduction, but greater knee abduction and knee internal rotation compared to experienced runners. Differences in knee joint position may be explained by coordination of hip and ankle motion. Greater knee abduction and knee internal rotation displayed by novice runners compared with experienced runners may help to explain their higher risk for injury.

The Reliability and Validity of the Loadsol® under Various Walking and Running Conditions.

The assessment of loading during walking and running has historically been limited to data collection in laboratory settings or with devices that require a computer connection. This study aims to determine if the loadsol®-a single sensor wireless insole-is a valid and reliable method of assessing force. Thirty (17 male and 13 female) recreationally active individuals were recruited for a two visit study where they walked (1.3 m/s) and ran (3.0 and 3.5 m/s) at a 0%, 10% incline, and 10% decline, with the visits approximately one week apart. Ground reaction force data was collected on an instrumented treadmill (1440 Hz) and with the loadsol® (100 Hz). Ten individuals completed the day 1 protocol with a newer 200 Hz loadsol®. Intraclass correlation coefficients (ICC3,k) were used to assess validity and reliability and Bland⁻Altman plots were generated to better understand loadsol® validity. Across conditions, the peak force ICCs ranged from 0.78 to 0.97, which increased to 0.84⁻0.99 with the 200 Hz insoles. Similarly, the loading rate ICCs improved from 0.61 to 0.97 to 0.80⁻0.96 and impulse improved from 0.61 to 0.97 to 0.90⁻0.97. The 200 Hz insoles may be needed for loading rate and impulse in running. For both walking and running, the loadsol® has excellent between-day reliability (>0.76).

Statistical Parametric Mapping as a Measure of Differences Between Limbs: Applications to Clinical Populations.

In healthy individuals, symmetrical lower-extremity movement is often assumed and calculated using discrete points during various tasks. However, measuring overall movement patterns using methods such as statistical parametric mapping (SPM) may allow for better interpretation of human movement. This study demonstrated the ability of SPM to assess interlimb differences in lower-extremity movement during 2 example tasks: running and landing. Three-dimensional motion analysis was used to determine sagittal and frontal plane lower-extremity joint angles in (1) young and older individuals during running and (2) patients with anterior cruciate ligament reconstruction and uninjured control athletes during landing. Interlimb differences within each group were compared using SPM and paired t tests on peak discrete angles. No differences between limbs were found between young and older runners using SPM. Peak ankle eversion and plantar flexion angles differed between limbs in young and older runners. Sagittal plane hip angle varied between limbs in uninjured control athletes. Frontal plane ankle angle and sagittal plane knee and hip angles differed between limbs in patients with anterior cruciate ligament reconstruction using SPM and discrete analysis. These data suggest that SPM can be useful to determine clinically meaningful interlimb differences during running and landing in multiple populations.

Changes in Vertical and Joint Stiffness in Runners With Advancing Age.

Powell, DW and Williams, DSB. Changes in vertical and joint stiffness in runners with advancing age. J Strength Cond Res 32(12): 3425-3431, 2018-Age-related changes in the neuromuscular system underlie reduced performance and injury but may be mitigated through regular physical activity. It was hypothesized that older (OLD) compared with young (YOUNG) adults would exhibit greater vertical and joint stiffness when running at 3.35 m·s. Nine YOUNG and 10 OLD runners performed over ground running trials while three-dimensional biomechanics were recorded. Ankle and knee joint angles, moments and stiffness values were compared between YOUNG & OLD. YOUNG had smaller vertical stiffness (p = 0.01; YOUNG: 32.8 ± 3.6; OLD: 38.1 ± 5.7) and greater joint stiffness than OLD at the ankle (p = 0.04; YOUNG: 0.134 ± 0.021; OLD: 0.118 ± 0.017) and knee (p = 0.01; YOUNG: 0.119 ± 0.016; OLD: 0.098 ± 0.014). YOUNG exhibited greater peak knee flexion angles (p = 0.04; YOUNG: 43.4 ± 6.5°; OLD: 39.1 ± 2.6°), and peak ankle plantarflexion (p = 0.02; YOUNG: -2.8 ± 0.4 Nm·kg; OLD: -2.5 ± 0.1 Nm·kg) and knee extension moments (p < 0.01; 2.6 ± 0.3 Nm·kg; OLD: 2.1 ± 0.2 Nm·kg) than OLD whereas no differences were observed in peak ankle dorsiflexion angles (p = 0.44; YOUNG: 23.6 ± 4.2°; OLD: 23.4 ± 2.1°). The findings of this study suggest that OLD compared with YOUNG adults adopt altered lower extremity biomechanics. These altered running biomechanics by seek to minimize the metabolic cost of running or may be a function of reduced lower extremity strength and power.

Lower Extremity Joint Work During Acceleration, Deceleration, and Steady State Running.

Running during sports and for physical activity often requires changes in velocity through acceleration and deceleration. While it is clear that lower extremity biomechanics vary during these accelerations and decelerations, the work requirements of the individual joints are not well understood. The purpose of this investigation was to measure the sagittal plane mechanical work of the individual lower extremity joints during acceleration, deceleration, and steady-state running. Ten runners were compared during acceleration, deceleration, and steady-state running using three-dimensional kinematics and kinetics measures. Total positive and negative joint work, and relative joint contributions to total work were compared between conditions. Total positive work progressively increased from deceleration to acceleration. This was due to greater ankle joint work during acceleration. While there was no significant change in total negative work during deceleration, there was a greater relative contribution of the knee to total negative work with a subsequent lower relative ankle negative work. Each lower extremity joint exhibits distinct functional roles in acceleration compared with deceleration during level running. Deceleration is dominated by greater contributions of the knee to negative work while acceleration is associated with a greater ankle contribution to positive work.

Hip arthroscopy in the setting of hip arthroplasty.

PURPOSE: Hip arthroscopy has traditionally been viewed as a hip preservation procedure performed in patients with native joint pathology. However, as the list of indications for arthroscopic hip intervention grows, further advances are expanding its use. The purpose of this systematic review was to examine existing evidence supporting the use of hip arthroscopy in the setting of hip arthroplasty. METHODS: Using predetermined inclusion criteria, EMBASE, MEDLINE and PubMed were searched for articles addressing arthroscopic hip surgery performed in hips containing joint replacement arthroplasties. Inclusion criteria limited our search to human and English language studies addressing articles where clear surgical indications are described. Article screening was conducted in duplicate. RESULTS: Seven-hundred and forty-three studies were retrieved before duplicate screening, and 18 satisfied inclusion criteria. Eleven case series, six case reports and one prospective cohort study are included. In total, 171 patients underwent hip arthroscopy following previous arthroplasty. Indications for arthroscopy included iliopsoas tendinopathy (35.8%), symptomatic hips with no clear diagnosis despite extensive investigation (24.6%), periprosthetic infection (6.4%) and intra-articular loose bodies (3.5%). Almost all patients who underwent hip arthroscopy experienced positive outcomes from the procedure. CONCLUSION: Hip arthroscopy after hip arthroplasty is supported by our systematic review for a variety of indications. Hip arthroscopy can be a safe and effective method of treating hip arthroplasty patients with iliopsoas tendinopathy. Hip arthroscopy also has utility in patients with symptomatic hip arthroplasty despite exhaustion of other diagnostic avenues. LEVEL OF EVIDENCE: A systematic review of level IV studies.

Vascular endothelial growth factor D expression is a potential biomarker of bevacizumab benefit in colorectal cancer.

BACKGROUND: Bevacizumab prolongs progression-free survival (PFS) in patients with metastatic colorectal cancer. We analysed the protein expression levels of vascular endothelial growth factor (VEGF) ligands and receptors to determine their prognostic and predictive effects. METHODS: We graded expression of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-R1, and VEGF-R2 to assess whether overexpression predicted bevacizumab resistance in samples from 268 of 471 patients randomised to capecitabine (C), capecitabine and bevacizumab (CB), or CB and mitomycin (CBM) in the MAX trial and extended the analysis to the CAIRO-2 population. RESULTS: Patients with low expression of VEGF-D (0, 1þ) benefited from bevacizumab treatment (PFS hazard ratio (HR) (C vs CBþCBM), 0.21; 95% CI, 0.08­0.55; overall survival (OS) HR, 0.35; 95% CI, 0.13­0.90). Patients with higher VEGF-D expression received less benefit (VEGF-D 2þ PFS HR, 0.67; 95% CI, 0.45­1.00; OS HR, 0.82; 95% CI, 0.52­1.30; VEGF-D 3þ PFS HR, 0.77; 95% CI, 0.50­1.17; OS HR, 1.28; 95% CI, 0.79­2.09) (P interaction o0.05). In CAIRO-2, there was no difference in PFS or OS according to VEGF-D expression. CONCLUSIONS: The predictive value of VEGF-D expression for bevacizumab may depend on the chemotherapy backbone used. Further evaluation is required before clinical utilisation.

Retinal gene therapy with a large MYO7A cDNA using adeno-associated virus.

Usher 1 patients are born profoundly deaf and then develop retinal degeneration. Thus they are readily identified before the onset of retinal degeneration, making gene therapy a viable strategy to prevent their blindness. Here, we have investigated the use of adeno-associated viruses (AAVs) for the delivery of the Usher 1B gene, MYO7A, to retinal cells in cell culture and in Myo7a-null mice. MYO7A cDNA, under control of a smCBA promoter, was packaged in single AAV2 and AAV5 vectors and as two overlapping halves in dual AAV2 vectors. The 7.9-kb smCBA-MYO7A exceeds the capacity of an AAV vector; packaging of such oversized constructs into single AAV vectors may involve fragmentation of the gene. Nevertheless, the AAV2 and AAV5 single vector preparations successfully transduced photoreceptor and retinal pigment epithelium cells, resulting in functional, full-length MYO7A protein and correction of mutant phenotypes, suggesting successful homologous recombination of gene fragments. With discrete, conventional-sized dual AAV2 vectors, full-length MYO7A was detected, but the level of protein expression was variable, and only a minority of cells showed phenotype correction. Our results show that MYO7A therapy with AAV2 or AAV5 single vectors is efficacious; however, the dual AAV2 approach proved to be less effective.

The Running Readiness Scale as an Assessment of Kinematics Related to Knee Injury in Novice Female Runners.

CONTEXT: Frontal- and transverse-plane kinematics have been prospectively identified as risk factors for running-related injuries in females. The Running Readiness Scale (RRS) may allow for clinical evaluation of these kinematics. OBJECTIVES: To determine the reliability and validity of the RRS as an assessment of frontal- and transverse-plane running kinematics. DESIGN: Cross-sectional study. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 56 novice female runners (median [interquartile range] age = 34 years [26-47 years]). MAIN OUTCOME MEASURE(S): We collected 3-dimensional kinematics during running and RRS tasks: hopping, plank, step-ups, single-legged squats, and wall sit. Five clinicians assessed RRS performances 3 times each. Interrater and intrarater reliabilities of the total RRS score and individual tasks were calculated using the intraclass correlation coefficient and Fleiss κ, respectively. Pearson product moment correlation coefficients between peak joint angles measured during running and the same angles measured during RRS tasks were computed. Peak joint angles of high- and low-scoring participants were compared. RESULTS: Interrater and intrarater reliabilities of assessment of the total RRS scores were good (intraclass correlation coefficients = 0.75 and 0.80, respectively). Reliability of assessing individual tasks was moderate to almost perfect (κ = 0.58-1.00). Peak hip adduction, contralateral pelvic drop, and knee abduction during running were correlated with the same angles measured during hopping, step-ups, and single-legged squats (r = 0.537-0.939). Peak knee internal rotation during running was correlated with peak knee internal rotation during step-ups (r = 0.831). Runners who scored high on the RRS demonstrated less knee abduction during running (P ≤ .01). CONCLUSIONS: The RRS may effectively assess knee abduction in novice runners, but evaluation criteria or tasks may need to be modified to effectively characterize pelvic and transverse-plane knee kinematics.

Frontal plane landing mechanics in high-arched compared with low-arched female athletes.

OBJECTIVE: To examine ground reaction forces (GRFs); frontal plane hip, knee, and ankle joint angles; and moments in high-arched (HA) and low-arched (LA) athletes during landing. DESIGN: Experimental study. SETTING: Controlled research laboratory. PARTICIPANTS: Twenty healthy female recreational athletes (10 HA and 10 LA). INTERVENTIONS: Athletes performed 5 barefoot drop landings from a height of 30 cm. MAIN OUTCOME MEASURES: Frontal plane ankle, knee, and hip joint angles (in degrees) at initial contact, peak vertical GRF, and peak knee flexion; peak ankle, knee, and hip joint moments in the frontal plane. RESULTS: Vertical GRF profiles were similar between HA and LA athletes (P = 0.78). The HA athletes exhibited significantly smaller peak ankle inversion angles than the LA athletes (P = 0.01) at initial contact. At peak vertical GRF, HA athletes had significantly greater peak knee (P = 0.01) and hip abduction angles than LA athletes (P = 0.02). There were no significant differences between HA and LA athletes in peak joint moments (hip: P = 0.68; knee: P = 0.71; ankle: P = 0.15). CONCLUSIONS: These findings demonstrate that foot type is associated with altered landing mechanics, which may underlie lower extremity injuries. The ankle-driven strategy previously reported in female athletes suggests that foot function may have a greater relationship with lower extremity injury than that in male athletes. Future research should address the interaction of foot type and gender during landing tasks.

Physical therapy services utilization and length of stay for obese patients following traumatic leg fracture.

BACKGROUND: Obesity is an increasing epidemic that can complicate the treatment of simple injuries and can increase health care costs. The purpose of the present study was to determine whether obesity is a factor in the utilization of inpatient physical therapy services and length of stay following a traumatic lower leg fracture. METHODS: A retrospective study of patients admitted to the hospital in 2005 and 2006 with a primary discharge diagnosis of lower leg or ankle fracture was conducted. Inclusion criteria were age > or = 18 years, only 1 involved lower extremity, and nonweight-bearing on the affected extremity per physician orders. Patients were excluded from the study if they had a fibular fracture only, pathological fractures, multiple trauma, severe cardiac or vascular comorbidities, or cognitive impairments. Data were compiled into 3 categories on the basis of body mass index (BMI): < 30, 30-35, > 35. Physical therapy services were measured in 15-minute units of time. These data were analyzed by within-group and between-group comparisons and with regression analysis. RESULTS: A total of 181 patients with a primary discharge diagnosis of distal lower extremity or ankle fracture were included in the study. Patients with a BMI >35 used more physical therapy services (mean services, 9.8 units) than did patients with a BMI of 30-35 (mean services, 6.2 units) or a BMI <30 (mean services, 5.6 units) (P = .001). Length of stay was also highest among patients with a BMI >35. LIMITATIONS: Factors other than BMI may be associated with length of stay and physical therapy use and may confound the association. CONCLUSION: Previous studies have shown that there is an increase in health care utilization among the bariatric population. The present study demonstrates similar findings for physical therapy services. Increased length of stay and physical therapy utilization among the bariatric population also result in increased staff utilization and equipment costs.

Foot and Shank Coordination During Walking in Copers Compared With Patients With Chronic Ankle Instability and Controls.

Background: Chronic ankle instability (CAI) alters sensorimotor function and joint coordination, but ankle coordination during walking in copers (patients with a history of ankle sprain without any residual symptoms of CAI) remains unknown. Purpose: To identify foot and shank coordination patterns that discriminate among individuals with CAI, copers, and healthy controls and to investigate whether copers display a different strategy to overcome altered sensorimotor function after a lateral ankle sprain compared with individuals with CAI and healthy controls. Study Design: Controlled laboratory study. Methods: A total of 51 participants (17 participants with CAI, 17 copers, 17 healthy controls) walked on an instrumented treadmill at a fixed speed of 1.20 m/s for a 10-second trial, from which 8 consecutive gait cycles were extracted for analysis. Heel strike and toe-off were identified for each stance phase, and each stance phase was normalized to 100 time frames. A curve analysis was performed to detect group mean differences in vector coding coupling angles and coordination variabilities for sagittal plane ankle motion/transverse plane tibial plane motion (SAK/TT) and frontal plane ankle motion/transverse plane tibial motion (FAK/TT) with 90% CIs. Results: During the terminal stance, CAI and coper groups demonstrated an inversion-tibial external rotation coupling, while controls displayed a dorsiflexion-tibial internal rotation strategy. During midstance, there were no differences between the coper, CAI, or control groups. At 0% to 20% of stance, the CAI group showed the most variability, while copers showed the least. During midstance, both copers and controls displayed an increase in variability earlier than the CAI group. The CAI group displayed a peak in variability from 39% to 43% of stance, which was greater than copers. During the propulsive phase (from heel-off to toe-off), the CAI group showed greater SAK/TT variability than both copers and controls. Similar to SAK/TT variability, the CAI group showed an earlier peak in FAK/TT variability compared with controls. Conclusion: The CAI, coper, and control groups displayed different ankle joint coupling patterns and coordination variability during a walking gait cycle. Clinical Relevance: Copers may have the ability to alter their coordination during walking, which may help us understand the underlying mechanism of CAI.

'Candidatus Pasteuria aldrichii', an obligate endoparasite of the bacterivorous nematode Bursilla.

A novel bacterium of the genus Pasteuria was discovered parasitizing bacterivorous nematodes of the genus Bursilla, in selected bermudagrass (Cynodon) field plots in Davie, FL, USA. Soil containing this bacterium was sampled and supplied with bi-weekly inoculations of cultured species of the genus Bursilla in order to build and maintain a source of endospores for continuous in vivo conservation of the bacteria for further study and characterization. 16S rRNA gene sequence similarities supported its congeneric ranking with other members of the genus Pasteuria that have been identified from nematodes and cladocerans. There were, however, no clear sister candidates for this organism, which supported the evidence of endospore ultrastructure and host-range studies, suggesting it belonged to a novel taxon. Because members of the genus Pasteuria cannot yet be isolated, definitive type strains could not be maintained; therefore, the name 'Candidatus Pasteuria aldrichii' is proposed for this organism.

Frontal and sagittal plane biomechanics during drop jump landing in boys who are obese.

PURPOSE: To investigate the frontal and sagittal plane lower extremity biomechanics during drop jump landings in boys who were obese and boys who were of healthy weight. METHODS: Twelve boys participated, 6 were considered as healthy weight (body mass index for age <85%, age 11.0 +/- 0.8 years), and 6 were considered as obese (body mass index for age >95%, age 12.1 +/- 0.7 years). Three-dimensional data were collected during landing from a drop jump. Group means were compared using Student t tests (alpha = 0.05). RESULTS: Significant differences were found in peak hip adduction moment, timing of peak dorsiflexion and knee flexion angles, and timing of peak knee extension and abduction moments. CONCLUSIONS: Boys who were obese exhibited significant differences in frontal and sagittal plane biomechanics when landing from a jump compared with healthy weight peers. These differences could place boys who are obese at greater risk for lower extremity injuries when they engage in jump-landing activities.

A case of ANCA-associated vasculitis presenting de novo in pregnancy, successfully treated with rituximab.

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitides are rare small vessel vasculitides of unknown cause. The pathogenic role of MPO-ANCA in the vasculitides has been supported using various animal models, with B-cells playing a role in the disease pathogenesis. Pregnancy in the presence of an autoimmune disease such as vasculitis is often associated with significant morbidity. Little is known about the outcomes when women present with de novo vasculitis during pregnancy, and the appropriate management of such presentations is unclear. We describe a case of a 33-year-old female presenting in her second pregnancy with new onset ANCA vasculitis at 12 weeks' gestation. She was successfully treated with prednisolone and rituximab, and delivered a healthy 2.8 kg boy at 36 weeks' gestation with no clinical manifestations of vasculitis or neutropenia in the neonate.

Ankle Coordination in Chronic Ankle Instability, Coper, and Control Groups in Running.

PURPOSE: Coordination and coordination variability have been used as a measure of the function and flexibility of the sensorimotor system during running. Chronic ankle instability (CAI) is associated with altered sensorimotor system function compared with individuals without CAI. Copers may have adopted protective sensorimotor adaptations to prevent repeated ankle sprains; however, their coordination strategies between the foot and shank have not been investigated. We compared joint coupling angles and coordination variability using vector coding between individuals with CAI, copers, and controls. METHODS: Seventeen individuals with CAI, 17 copers, and 17 controls ran on the treadmill at a fixed speed of 2.68 m·s. A 10-s trial of continuous data was collected for kinematic analysis. The first five complete strides were used for vector coding. Means of the vector coding angles and variability of frontal plane ankle motion/transverse plane tibia motion and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) were calculated. A curve analysis with 90% confidence intervals was performed to detect differences between groups. RESULTS: Controls demonstrated greater angles of SAK/TT than individuals with CAI and greater angles of FAK/TT than copers during the second half of stance. In general, the control group demonstrated greater variability than individuals with CAI and copers, and copers demonstrated greater variability than individuals with CAI. CONCLUSIONS: Chronic ankle instability and copers demonstrated different coordination strategies than controls during loading and propulsion, adding evidence to support a sensorimotor deficit or compensation. Further, limited variability in people with history of CAI during impact and midstance may contribute to higher risk of reinjury, and be an important area for further research.

Identification of actin filaments in the rhabdomeral microvilli of Drosophila photoreceptors.

The phototransductive microvilli of arthropod photoreceptors each contain an axial cytoskeleton. The present study shows that actin filaments are a component of this cytoskeleton in Drosophila. Firstly, actin was detected in the rhabdomeral microvilli and in the subrhabdomeral cytoplasm by immunogold labeling with antiactin. Secondly, the rhabdomeres were labeled with phalloidin, indicating the presence of filamentous actin. Finally, the actin filaments were decorated with myosin subfragment-1. The characteristic arrowhead complex formed by subfragment-1 decoration points towards the base of the microvilli, so that the fast growing end of each filament is at the distal end of the microvillus, where it is embedded in a detergent-resistant cap. Each microvillus contains more than one actin filament. Decorated filaments extend the entire length of each microvillus and project into the subrhabdomeral cytoplasm. This organization is comparable to that of the actin filaments in intestinal brush border microvilli. Similar observations were made with the photoreceptor microvilli of the crayfish, Procambarus. Our results provide an indication as to how any myosin that is associated with the rhabdomeres might function.

Localization of peripherin/rds in the disk membranes of cone and rod photoreceptors: relationship to disk membrane morphogenesis and retinal degeneration.

The outer segments of vertebrate rod photoreceptor cells consist of an ordered stack of membrane disks, which, except for a few nascent disks at the base of the outer segment, is surrounded by a separate plasma membrane. Previous studies indicate that the protein, peripherin or peripherin/rds, is localized along the rim of mature disks of rod outer segments. A mutation in the gene for this protein has been reported to be responsible for retinal degeneration in the rds mouse. In the present study, we have shown by immunogold labeling of rat and ground squirrel retinas that peripherin/rds is present in the disk rims of cone outer segments as well as rod outer segments. Additionally, in the basal regions of rod and cone outer segments, where disk morphogenesis occurs, we have found that the distribution of peripherin/rds is restricted to a region that is adjacent to the cilium. Extension of its distribution from the cilium coincides with the formation of the disk rim. These results support the model of disk membrane morphogenesis that predicts rim formation to be a second stage of growth, after the first stage in which the ciliary plasma membrane evaginates to form open nascent disks. The results also indicate how the proteins of the outer segment plasma membrane and the disk membranes are sorted into their separate domains: different sets of proteins may be incorporated into membrane outgrowths during different growth stages of disk morphogenesis. Finally, the presence of peripherin/rds protein in both cone and rod outer segment disks, together with the phenotype of the rds mouse, which is characterized by the failure of both rod and cone outer segment formation, suggest that the same rds gene is expressed in both types of photoreceptor cells.

Differential localizations of and requirements for the two Drosophila ninaC kinase/myosins in photoreceptor cells.

The ninaC gene encodes two retinal specific proteins (p132 and p174) consisting of a protein kinase domain joined to a domain homologous to the head region of the myosin heavy chain. The putative myosin domain of p174 is linked at the COOH-terminus to a tail which has some similarities to myosin-I tails. In the current report, we demonstrate that the ninaC mutation results in light- and age-dependent retinal degeneration. We also show that ninaC flies display an electrophysiological phenotype before any discernible retinal degeneration indicating that the electrophysiological defect is the primary effect of the mutation. This suggests that ninaC has a role in phototransduction and that the retinal degeneration is a secondary effect resulting from the defect in phototransduction. To examine the requirements for the individual ninaC isoforms, mutant alleles were generated which express only p132 or p174. Elimination of p174 resulted in a ninaC phenotype as strong as the null allele; however, elimination of p132 had little if any effect. As a first step in investigating the basis for the difference in requirements for p174 and p132 we performed immuno-localization at the electron microscopic level and found that the two isoforms display different subcellular distributions in the photoreceptor cells. The p132 protein is restricted primarily to the cytoplasm and p174 to the rhabdomeres, the microvillar structure which is the site of action of many of the steps in phototransduction. This suggests that the p174 myosin-I type tail is the domain responsible for association with the rhabdomeres and that the substrate for the p174 putative kinase may be a rhabdomeric protein important in photo-transduction.