Novel Blood Biomarkers Are Associated with White Matter Lesions in Fragile X- Associated Tremor/Ataxia Syndrome.

BACKGROUND: The need for accessible cellular biomarkers of neurodegeneration in carriers of the fragile X mental retardation 1 (FMR1) premutation (PM) alleles. OBJECTIVE: To assess the mitochondrial status and respiration in blood lymphoblasts from PM carriers manifesting the fragile X-associated tremor/ataxia syndrome (FXTAS) and non-FXTAS carriers, and their relationship with the brain white matter lesions. METHODS: Oxygen consumption rates (OCR) and ATP synthesis using a Seahorse XFe24 Extracellular Flux Analyser, and steady-state parameters of mitochondrial function were assessed in cultured lymphoblasts from 16 PM males (including 11 FXTAS patients) and 9 matched controls. The regional white matter hyperintensity (WMH) scores were obtained from MRI. RESULTS: Mitochondrial respiratory activity was significantly elevated in lymphoblasts from PM carriers compared with controls, with a 2- to 3-fold increase in basal and maximum OCR attributable to complex I activity, and ATP synthesis, accompanied by unaltered mitochondrial mass and membrane potential. The changes, which were more advanced in FXTAS patients, were significantly associated with the WMH scores in the supratentorial regions. CONCLUSION: The dramatic increase in mitochondrial activity in lymphoblasts from PM carriers may represent either the early stages of disease (specific alterations in short-lived blood cells) or an activation of the lymphocytes under pathological situations. These changes may provide early, convenient blood biomarkers of clinical involvements.

Up-and-down shift in residence depth of slickheads (Alepocephalidae) revealed by otolith stable oxygen isotopic composition.

Otolith δ(18)O profiles for four slickhead species (Alepocephalidae) suggested that Alepocephalus umbriceps, Talismania okinawensis and Rouleina watasei migrated hundreds of metres to shallower depths during the juvenile to young stages before returning to their original depth or even deeper waters. Xenodermichthys nodulosus gradually shifted residence depth from shallow to deeper water during their life. These migratory patterns indicated that the slickheads examined had allopatric residence depths at different life stages, which might enhance the pelagic survival and growth rates of the juvenile and young fishes.

[Clinical analysis of the correlation between the expression of soluble B cell maturation antigen and the efficacy of chimeric antigen receptor T cell targeting B cell maturation antigen in patients with multiple myeloma].

Objective: The effect of bone marrow soluble B cell maturation antigen (sBCMA) expression on the efficacy and side effects of chimeric antigen receptor (CAR) -modified T-cell-targeting B cell maturation antigen (BCMA) in patients with multiple myeloma (MM) . Methods: This study involved 29 patients with relapsed or refractory MM (RRMM) who received humanized anti-BCMA CAR-T cell clinical trials from January 2018 to December 2021. The expression of sBCMA in bone marrow before and after anti-BCMA CAR-T cell treatment was detected by flow cytometry and compared. Results: ①Two months after BCMA CAR-T cell treatment, 20 patients (68.97%) achieved an overall response (OR), whereas nine patients had stable disease (SD) or miner emission (MR). ②The expression of sBCMA in the bone marrow of 20 patients with OR was higher before treatment than after [26 926 (18 215, 32 488) ng/L vs 9 968 (6 634, 11 459) ng/L; P<0.001]; no significant difference was observed in patients with MR and SD [41 187 (33 816, 47 046) ng/L vs. 33 954 (31 569, 36 256) ng/L; P=0.145]; sBCMA expression in patients with OR before CAR-T cell treatment was lower than in patients with MR and SD (P=0.005). ③No significant linear correlation was found between the peak value of CAR-T cells and sBCMA expression in the bone marrow of all 29 patients with RRMM (R(2)=0.035, P=0.330). ④No significant difference in sBCMA expression was found between grades 0-1 CRS group (13 patients) and grades 2-4 CRS group [16 patients; 32 045 (18 742, 40 801) ng/L vs 29 102 (24 679, 38 776) ng/L, P=0.879], nor between grade 0 ICANS group (22 patients) and grade 1-3 ICANS group [seven patients; 30 073 (19 375, 40 065) ng/L vs 33 816 (22 933, 43 459) ng/L, P=0.763]. Conclusion: sBCMA expression in the bone marrow is related to the efficacy of BCMA CAR-T cell therapy in patients with RRMM, but is not significantly correlated with the severity of adverse events. It may serve as a predictive biomarker for the efficacy of BCMA CAR-T cell therapy in these patients.

A Conserved Role for LRRK2 and Roco Proteins in the Regulation of Mitochondrial Activity.

Parkinson's Disease (PD) is the second most common neurodegenerative disease world-wide. Mutations in the multidomain protein Leucine Rich Repeat Kinase 2 (LRRK2) are the most frequent cause of hereditary PD. Furthermore, recent data suggest that independent of mutations, increased kinase activity of LRRK2 plays an essential role in PD pathogenesis. Isolated mitochondria of tissue samples from PD patients carrying LRRK2 mutations display a significant impairment of mitochondrial function. However, due to the complexity of the mitochondrial signaling network, the role of LRRK2 in mitochondrial metabolism is still not well understood. Previously we have shown that D. discoideum Roco4 is a suitable model to study the activation mechanism of LRRK2 in vivo. To get more insight in the LRRK2 pathways regulating mitochondrial activity we used this Roco4 model system in combination with murine RAW macrophages. Here we show that both Dictyostelium roco4 knockout and cells expressing PD-mutants show behavioral and developmental phenotypes that are characteristic for mitochondrial impairment. Mitochondrial activity measured by Seahorse technology revealed that the basal respiration of D. discoideum roco4- cells is significantly increased compared to the WT strain, while the basal and maximal respiration values of cells overexpressing Roco4 are reduced compared to the WT strain. Consistently, LRRK2 KO RAW 264.7 cells exhibit higher maximal mitochondrial respiration activity compared to the LRRK2 parental RAW264.7 cells. Measurement on isolated mitochondria from LRRK2 KO and parental RAW 264.7 cells revealed no difference in activity compared to the parental cells. Furthermore, neither D. discoideum roco4- nor LRRK2 KO RAW 264.7 showed a difference in either the number or the morphology of mitochondria compared to their respective parental strains. This suggests that the observed effects on the mitochondrial respiratory in cells are indirect and that LRRK2/Roco proteins most likely require other cytosolic cofactors to elicit mitochondrial effects.

[Efficacy and safety of CD19 chimeric antigen receptor T cells for the treatment of 22 patients with B-cell lymphoma].

Objective: To investigate the efficacy and safety of CD19 chimeric antigen receptor T (CAR-T) lymphocytes for the treatment of B cell lymphoma. Methods: A total of 22 patients with B-cell lymphoma from February 1, 2017 to July 1, 2018 were reviewed to evaluate the efficacy and adverse reactions of CD19 CAR-T. Results: Of 22 patients with B-cell lymphoma received CD19 CAR-T cells, the median dose of CAR-T cells was 7.2 (2.0-12.0) ×106/kg. Nine of 12 cases of relapse refractory patients were overall response. Complete remission (CR) occurred in 2 of 12 patients, partial remission (PR) in 7 of 12 patients. The overall response in minor residual disease positive (MRD) group was 8 of 10 patients. CD19 CAR-T cells proliferated in vivo and were detectable in the blood of patients. The peak timepoints of CAR-T cells proliferated in the relapsed refractory and MRD positive groups were 12 (5-19) and 4.5 (1-12) days after treatment respectively, and among peripheral blood cells, CAR-T cells accounted for 10.10% (3.55%-24.74%) and 4.02% (2.23%-28.60%) of T lymphocytes respectively. The MRD positive patients achieved sustained remissions during a median follow-up of 8 months (rang 3-18 months) . None of all the patients relapsed during a median follow-up time of 10 months (3-18 months) . However, 7 PR responders of the relapsed refractory patients maintained a good condition for 1.5-6.0 months. One patient bridged to hematopoietic stem cell transplantation, another one sustained remission for 12 months. Cytokine-release syndrome (CRS) occurred in 14 patients with grade 1-2 CRS in MRD positive group and grade 3 CRS in relapsed refractory group. Conclusions: CAR-T cell therapy not only played a role in the rescue treatment of relapsed and refractory patients, but also produced a surprising effect in the consolidation and maintenance of B-cell lymphoma. CD19 CAR-T cells might be more effective in the treatment of MRD positive B-cell lymphoma patients than in the refractory or relapsed cases. High response rate was observed with fewer adverse reactions.

Biomechanical strength impact of lateral wall breach on spinal pedicle screw fixation.

OBJECTIVE: The purpose of our study was to make a comparison between the fixation strength of optimum placed pedicle screw (OS) and re-directionally accurate placed pedicle screw (RS) after lateral pedicle breach. PATIENTS AND METHODS: A total of 30 fresh lumbar vertebrae (L1-5) were gained from 6 male or female pigs weighing about 100 kg, which were divided into 2 groups according to different ways of pedicle screws placement: OS group (n=30) and RS group (n=30). MTS machine was employed to detect the screw loosening and axial pullout. We examined seating torque, screw-loosening force, the maximal torque and post-loosening axial pullout in each pedicle screw. RESULTS: Maximal insertion torque of OS was (111.6±8.4) N•cm and RS was (79.0±6.3) N•cm, which indicated a significant difference (Z=3.012, p=0.003). Seating torque of OS and RS were (85.9±5.6) N•cm and (60.3±4.8) N•cm separately, and the difference was statistically significant (Z=2.799, p=0.006). Screw loosening force of OS and RS were (75.9±7.0) N and (52.4±6.3) N respectively, and the difference was statistically significant (Z=2.652, p=0.003). Post-loosening axial pullout force of OS and RS were (328.5±11.3) N and (269.1±9.6) N separately, demonstrating that the difference was statistically significant (Z=2.865, p=0.004). CONCLUSIONS: RS placement is an alternative for remediation following a lateral wall breach evidenced by significantly decreased seating torque, screw loosening force, the maximal torque and post-loosening axial pullout compared with OS.

A multi-level drill guide template improves the accuracy of pedicle screw placement in lumbar spine.

OBJECTIVE: Free-hand technique is widely used in pedicle screw placement for lumbar spine and generally safe; however, screw malposition still occurs. To develop a novel multi-level drill guide template for pedicle screw placement in lumbar spine and evaluate its accuracy. MATERIALS AND METHODS: Twelve lumbar cadaveric specimens were randomly allocated into guide template group (n=6) and free-hand group (n=6). Computed tomography (CT) scans were obtained for reconstruction of three-dimensional (3D) model of each lumbar vertebra, and further an individual guide template was designed. Then the templates and their corresponding vertebra were developed by rapid prototyping (RP) technology. With the guide of the templates, screws were inserted via mini-open Wiltse approach. The positions of the screws were assessed based on postoperative CT images. RESULTS: In total, 120 pedicle screws inserted (guide template group: n=60 vs. free-hand group: n=60). For all 30 vertebras in the guide template group, all pre-designed personalized drill guide templates can be fitted into the facet joints of each vertebra well. Furthermore, our results revealed a significant improvement for the guide template group in the accuracy rate (p=0.026). CONCLUSIONS: Armed with advantages of minimal invasion, enhanced accuracy and safety, the novel technique of multi-level drill guide template can be properly applied in pedicle screw placement for lumbar spine and promises to be a potential option in clinical application.

Proteobacterial Origin of Protein Arginine Methylation and Regulation of Complex I Assembly by MidA.

The human protein arginine methyltransferase NDUFAF7 controls the assembly of the ∼1-MDa mitochondrial complex I (CI; the NADH ubiquinone oxidoreductase) by methylating its subunit NDUFS2. We determined crystal structures of MidA, the Dictyostelium ortholog of NDUFAF7. The MidA catalytic core domain resembles other eukaryotic methyltransferases. However, three large core loops assemble into a regulatory domain that is likely to control ligand selection. Binding of MidA to NDUFS2 is weakened by methylation, suggesting a mechanism for methylation-controlled substrate release. Structural and bioinformatic analyses support that MidA and NDUFAF7 and their role in CI assembly are conserved from bacteria to humans, implying that protein methylation already existed in proteobacteria. In vivo studies confirmed the critical role of the MidA methyltransferase activity for CI assembly, growth, and phototaxis of Dictyostelium. Collectively, our data elucidate the origin of protein arginine methylation and its use by MidA/NDUFAF7 to regulate CI assembly.

The Spectrum of Neurological and White Matter Changes and Premutation Status Categories of Older Male Carriers of the FMR1 Alleles Are Linked to Genetic (CGG and FMR1 mRNA) and Cellular Stress (AMPK) Markers.

The fragile X premutation (PM) allele contains a CGG expansion of 55-200 repeats in the FMR1 gene's promoter. Male PM carriers have an elevated risk of developing neurological and psychiatric changes, including an approximately 50% risk of the fragile X-associated tremor/ataxia syndrome (FXTAS). The aim of this study was to assess the relationships of regional white matter hyperintensities (wmhs) semi-quantitative scores, clinical status, motor (UPDRS, ICARS, Tremor) scales, and cognitive impairments, with FMR1-specific genetic changes, in a sample of 32 unselected male PM carriers aged 39-81 years. Half of these individuals were affected with FXTAS, while the non-FXTAS group comprised subcategories of non-affected individuals and individuals affected with non-syndromic changes. The dynamics of pathological processes at the cellular level relevant to the clinical status of PM carriers was investigated using the enzyme AMP-activated protein kinase (AMPK), which is a highly sensitive cellular stress-sensing alarm protein. This enzyme, as well as genetic markers - CGG repeat number and the levels of the FMR1 mRNA - were assessed in blood lymphoblasts. The results showed that the repeat distribution for FXTAS individuals peaked at 85-90 CGGs; non-FXTAS carriers were distributed within the lowest end of the PM repeat range, and non-syndromic carriers assumed an intermediate position. The size of the CGG expansion was significantly correlated, across all three categories, with infratentorial and total wmhs and with all motor scores, and the FMR1 mRNA levels with all the wmh scores, whilst AMPK activity showed considerable elevation in the non-FXTAS combined group, decreasing in the FXTAS group, proportionally to increasing severity of the wmhs and tremor/ataxia. We conclude that the size of the CGG expansion relates to the risk for FXTAS, to severity of infratentorial wmhs lesions, and to all three motor scale scores. FMR1 mRNA shows a strong association with the extent of wmhs, which is the most sensitive marker of the pathological process. However, the AMPK activity findings - suggestive of a role of this enzyme in the risk of FXTAS - need to be verified and expanded in future studies using larger samples and longitudinal assessment.

Strain softening of nano-scale fuzzy interfaces causes Mullins effect in thermoplastic polyurethane.

The strain-induced softening of thermoplastic polyurethane elastomers (TPUs), known as the Mullins effect, arises from their multi-phase structure. We used the combination of small- and wide- angle X-ray scattering (SAXS/WAXS) during in situ repeated tensile loading to elucidate the relationship between molecular architecture, nano-strain, and macro-scale mechanical properties. Insights obtained from our analysis highlight the importance of the 'fuzzy interface' between the hard and soft regions that governs the structure evolution at nanometre length scales and leads to macroscopic stiffness reduction. We propose a hierarchical Eshelby inclusion model of phase interaction mediated by the 'fuzzy interface' that accommodates the nano-strain gradient between hard and soft regions and undergoes tension-induced softening, causing the Mullins effect that becomes apparent in TPUs even at moderate tensile strains.

Association between H19 polymorphisms and osteosarcoma risk.

OBJECTIVE: The long non-coding RNA (lncRNA) H19, a maternally expressed imprinted gene, has involvement in cancer susceptibility and disease progression. However, the association between H19 polymorphisms and osteosarcoma susceptibility has remained elusive. We designed this case-control study to explore the association between H19 polymorphism and osteosarcoma risk. PATIENTS AND METHODS: In this study, we genotyped 4 tagger SNPs of the H19 gene in a case-control study including 193 osteosarcoma cases and 393 cancer-free controls. RESULTS: For the main effect analysis, rs217727 (G>A) was associated with osteosarcoma risk (GA/GG: adjusted OR = 1.51, 95% CI: 1.06-2.17, p = 0.024; AA/GG: adjusted OR = 1.89, 95% CI: 1.23-2.91, p = 0.004; additive model: adjusted OR = 1.35, 95% CI: 1.01-1.80, p = 0.043). CONCLUSIONS: This finding indicates that rs217727 polymorphism may play a role in genetic susceptibility to the risk of osteosarcoma, which may improve our understanding of the potential contribution of H19 SNPs to cancer pathogenesis.

Immortalized Parkinson's disease lymphocytes have enhanced mitochondrial respiratory activity.

In combination with studies of post-mortem Parkinson's disease (PD) brains, pharmacological and genetic models of PD have suggested that two fundamental interacting cellular processes are impaired - proteostasis and mitochondrial respiration. We have re-examined the role of mitochondrial dysfunction in lymphoblasts isolated from individuals with idiopathic PD and an age-matched control group. As previously reported for various PD cell types, the production of reactive oxygen species (ROS) by PD lymphoblasts was significantly elevated. However, this was not due to an impairment of mitochondrial respiration, as is often assumed. Instead, basal mitochondrial respiration and ATP synthesis are dramatically elevated in PD lymphoblasts. The mitochondrial mass, genome copy number and membrane potential were unaltered, but the expression of indicative respiratory complex proteins was also elevated. This explains the increased oxygen consumption rates by each of the respiratory complexes in experimentally uncoupled mitochondria of iPD cells. However, it was not attributable to increased activity of the stress- and energy-sensing protein kinase AMPK, a regulator of mitochondrial biogenesis and activity. The respiratory differences between iPD and control cells were sufficiently dramatic as to provide a potentially sensitive and reliable biomarker of the disease state, unaffected by disease duration (time since diagnosis) or clinical severity. Lymphoblasts from control and PD individuals thus occupy two distinct, quasi-stable steady states; a 'normal' and a 'hyperactive' state characterized by two different metabolic rates. The apparent stability of the 'hyperactive' state in patient-derived lymphoblasts in the face of patient ageing, ongoing disease and mounting disease severity suggests an early, permanent switch to an alternative metabolic steady state. With its associated, elevated ROS production, the 'hyperactive' state might not cause pathology to cells that are rapidly turned over, but brain cells might accumulate long-term damage leading ultimately to neurodegeneration and the loss of mitochondrial function observed post-mortem. Whether the 'hyperactive' state in lymphoblasts is a biomarker specifically of PD or more generally of neurodegenerative disease remains to be determined.

X-ray Study of Human Dental Tissues Affected by Erythroblastosis Fetalis.

Numerous diseases are known to cause microstructural alteration of dental tissues structure. One type in particular is associated with neonatal jaundice and circulation of bilirubin in blood at high concentration due to increased hemolysis in conditions such as erythroblastosis fetalis, septicemia, biliary atresia, and other causes of hyperbilirubinemia. In those conditions, the products of the catabolism of hemoglobin end up deposited in various tissues, including teeth, where they can present clinically as visibly stained brown/green teeth. There is almost no information on the nature or extent of the structural changes taking place in these conditions. Here, advanced nondestructive wide-angle synchrotron X-ray scattering techniques combined with scanning microscopy methods were used to investigate for the first time the ultrastructure of the dental hard tissues in an archival case of intrinsically pigmented green teeth. Despite no obvious elemental variation across the pigmented tissue region, the high-resolution crystallographic properties probed by wide-angle synchrotron X-ray scattering revealed an ultrastructural variation (orientation, particle size, and lattice parameter of hydroxyapatite crystallites) associated with a pigmentation line in dentine and with a distinct neonatal line in enamel.

One-stage pedicled omentum majus transplantation into thoracic cavity for treatment of chronic persistent empyema with or without bronchopleural fistula.

OBJECTIVE: Assessment of the present results of surgical treatment for chronic persistent empyema with or without bronchopleural fistula (BPF) using one-stage pedicled omentum majus transplantation into the thoracic cavity. METHODS: From November 1979 to December 1996, 50 patients with chronic persistent empyema were treated by pedicled omentum majus transplanted into the thoracic cavity. There were 35 men and 15 women, and the age range was 15-58 years. Empyema had been present for 0.5-18 years. Twenty-six of 35 cases with chronic tuberculous empyema and six of 15 cases with chronic bacterial empyema suffered from concomitant BPF (n = 32). In the latter, the most common organisms were Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. RESULTS: There were no perioperative deaths. Two cases had a significant air leak on the first postoperative day. One of them underwent rethoractomy 30 h after the initial operation to stop the fistula using intrathoracic omentum. Thoracic dead space disappeared in most of the operated cases and a sterilized dry cavity remained in some cases. CONCLUSIONS: One-stage pedicled omentum majus transposition is a safe and easy procedure for chronic persistent empyema and BPF, it breaks down residual or recurrent inflammatory foci mechanically and closes the BPF effectively with minimal deformity of the chest wall.

Effect of FK506 in reducing scar formation by inducing fibroblast apoptosis after sciatic nerve injury in rats.

We previously demonstrated that FK506, a generally applied immunosuppressant in organ transplantation, could promote peripheral nerve regeneration through reducing scar formation. However, little is known about how FK506 reduces scar formation. Herein we investigated the influence of FK506 on fibroblast proliferation and its correlation with scar formation after sciatic nerve injury in rats, and further explored the effect of FK506 on fibroblast proliferation and apoptosis in vitro. Masson staining and immunohistochemistry revealed that scar area and fibroblast number in the nerve anastomosis of sciatic nerve-injured rats were significantly reduced after FK506 administration. The scar area had a significant positive correlation with the fibroblast number, as detected by linear correlation analysis. CCK-8 assay and flow cytometry indicated that FK506 also inhibited proliferation and induced apoptosis of fibroblasts in vitro. It was primarily phosphorylation of JNK and ERK that were activated during the apoptosis of fibroblast. Pretreatment of cells with JNK inhibitor, SP600125, or ERK inhibitor, PD98059, could inhibit FK506-induced fibroblast apoptosis, respectively. Moreover, simultaneous application of both inhibitors had additive roles in cell protection from apoptosis. These results suggest that FK506-induced fibroblast apoptosis contributes to the suppression of fibroblast proliferation and then results in the reduction of scar formation in sciatic nerve-injured rat, and that JNK and ERK are involved in FK506-induced fibroblast apoptosis.

Import-associated translational inhibition: novel in vivo evidence for cotranslational protein import into Dictyostelium discoideum mitochondria.

To investigate protein import into the mitochondria of Dictyostelium discoideum, green fluorescent protein (GFP) was fused as a reporter protein either to variable lengths of the N-terminal region of chaperonin 60 (the first 23, 40, 80, 97, and 150 amino acids) or to the mitochondrial targeting sequence of DNA topoisomerase II. The fusion proteins were expressed in AX2 cells under the actin-15 promoter. Fluorescence images of GFP transformants confirmed that Dictyostelium chaperonin 60 is a mitochondrial protein. The level of the mitochondrially targeted GFP fusion proteins was unexpectedly much lower than the nontargeted (cytoplasmic) forms. The distinction between targeted and nontargeted protein activities was investigated at both the transcriptional and translational levels in vivo. We found that targeting GFP to the mitochondria results in reduced levels of the fusion protein even though transcription of the fusion gene and the stability of the protein are unaffected. [(35)S]methionine labeling and GFP immunoprecipitation confirmed that mitochondrially targeted GFP is translated at much slower rates than nontargeted GFP. The results indicate a novel phenomenon, import-associated translational inhibition, whereby protein import into the mitochondria limits the rate of translation. The simplest explanation for this is that import of the GFP fusion proteins occurs cotranslationally, i.e., protein synthesis and import into mitochondria are coupled events. Consistent with cotranslational import, Northern analysis showed that the GFP mRNA is associated with isolated mitochondria. This association occurred regardless of whether the GFP was fused to a mitochondrial leader peptide. However, the presence of an import-competent leader peptide stabilized the mRNA-mitochondria association, rendering it more resistant to extensive EDTA washing. In contrast with GFP, the mRNA of another test protein, aequorin, did not associate with the mitochondria, and its translation was unaffected by import of the encoded polypeptide into the mitochondria.

Chaperonin 60 and mitochondrial disease in Dictyostelium.

The single Dictyostelium chaperonin 60 gene, hspA, was cloned, sequenced and characterized. Sequence comparisons and a three-dimensional model for the structure of the encoded protein showed that it exhibits the conserved sequence and structural features expected for its role as the Dictyostelium mitochondrial chaperonin 60. Dictyostelium hspA contains two introns and, unusually for a member of this major heat shock gene family, is not stress-inducible in response to heat, cold or cadmium ions. Although transcription of hspA is down regulated during early Dictyostelium development in response to starvation, the levels of the chaperonin 60 protein remain constant throughout the life cycle. Consistent with the essential role of chaperonin 60 in mitochondrial biogenesis, we were unable to isolate mutants in which the hspA gene had been disrupted. However, transformants were isolated that exhibited differing levels of antisense inhibition of chaperonin 60 expression, depending upon the number of copies of the antisense-expressing plasmid in the genome. Orientation in phototaxis (and thermotaxis) was severely impaired in all antisense transformants, while growth and morphogenesis were markedly defective only in transformants with higher levels of antisense inhibition. This pattern of phenotypes is similar to that reported previously to result from targeted disruption of the mitochondrial large subunit rRNA gene in a subpopulation of mitochondria. This suggests that, regardless of the nature of the underlying genetic defect, mitochondrial deficiency impairs signal transduction more sensitively than other cellular activities.