The CRISPR/Cas9-Mediated Modulation of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 8 in Alfalfa Leads to Distinct Phenotypic Outcomes

Alfalfa (Medicago sativa L.) is the most widely grown perennial leguminous forage and is an essential component of the livestock industry. Previously, the RNAi-mediated down-regulation of alfalfa SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 8 (MsSPL8) was found to lead to increased branching, regrowth and biomass, as well as enhanced drought tolerance. In this study, we aimed to further characterize the function of MsSPL8 in alfalfa using CRISPR/Cas9-induced mutations in this gene. We successfully generated alfalfa genotypes with small insertions/deletions (indels) at the target site in up to three of four MsSPL8 alleles in the first generation. The efficiency of editing appeared to be tightly linked to the particular gRNA used. The resulting genotypes displayed consistent morphological alterations, even with the presence of up to two wild-type MsSPL8 alleles, including reduced leaf size and early flowering. Other phenotypic effects appeared to be dependent upon mutational dosage, with those plants with the highest number of mutated MsSPL8 alleles also exhibiting significant decreases in internode length, plant height, shoot and root biomass, and root length. Furthermore, MsSPL8 mutants displayed improvements in their ability to withstand water-deficit compared to empty vector control genotypes. Taken together, our findings suggest that allelic mutational dosage can elicit phenotypic gradients in alfalfa, and discrepancies may exist in terms of MsSPL8 function between alfalfa genotypes, growth conditions, or specific alleles. In addition, our results provide the foundation for further research exploring drought tolerance mechanisms in a forage crop.

Identification of Differential Drought Response Mechanisms in Medicago sativa subsp. sativa and falcata through Comparative Assessments at the Physiological, Biochemical, and Transcriptional Levels

Alfalfa (Medicago sativa L.) is an extensively grown perennial forage legume, and although it is relatively drought tolerant, it consumes high amounts of water and depends upon irrigation in many regions. Given the progressive decline in water available for irrigation, as well as an escalation in climate change-related droughts, there is a critical need to develop alfalfa cultivars with improved drought resilience. M. sativa subsp. falcata is a close relative of the predominantly cultivated M. sativa subsp. sativa, and certain accessions have been demonstrated to exhibit superior performance under drought. As such, we endeavoured to carry out comparative physiological, biochemical, and transcriptomic evaluations of an as of yet unstudied drought-tolerant M. sativa subsp. falcata accession (PI 641381) and a relatively drought-susceptible M. sativa subsp. sativa cultivar (Beaver) to increase our understanding of the molecular mechanisms behind the enhanced ability of falcata to withstand water deficiency. Our findings indicate that unlike the small number of falcata genotypes assessed previously, falcata PI 641381 may exploit smaller, thicker leaves, as well as an increase in the baseline transcriptional levels of genes encoding particular transcription factors, protective proteins, and enzymes involved in the biosynthesis of stress-related compounds. These findings imply that different falcata accessions/genotypes may employ distinct drought response mechanisms, and the study provides a suite of candidate genes to facilitate the breeding of alfalfa with enhanced drought resilience in the future.

Validity of the K-10 in detecting DSM-IV-defined depression and anxiety disorders among HIV-infected individuals

It has been suggested that an HIV diagnosis may increase the likelihood of mental disorders among infected individuals and that the progression of HIV may be hastened by mental disorders like anxiety and depression. Therefore, a brief screening measure, with good sensitivity/specificity for psychiatric diagnoses that could be given to HIV-infected individuals would be useful. We assessed the validity of the K-10, using the MINI International Neuropsychiatric Interview as the gold standard, in a sample of 429 HIV-infected adults enrolled in HIV care and treatment services near Cape Town, South Africa. There was significant agreement between the K-10 and the MINI-defined depressive and anxiety disorders. A receiver operating characteristic (ROC) curve analysis indicated that the K-10 showed agreeable sensitivity and specificity in detecting depression (area under the ROC curve, 0.77), generalized anxiety disorder (0.78), and posttraumatic stress disorder (PTSD) (0.77). The K-10 may be a useful screening measure for detecting mood and anxiety disorders, including PTSD, in patients with HIV/AIDS.

Role of US-guided fine-needle aspiration with on-site cytopathologic evaluation in management of nonpalpable breast lesions

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the accuracy of ultrasound (US)-guided fine-needle aspiration (FNA), with radiographic follow-up or surgical excision, in conjunction with on-site cytopathologic support in the management of nonpalpable breast lesions.

MATERIALS AND METHODS

The findings of 266 consecutive mammographically or sonographically identified, nonpalpable lesions (228 patients) that underwent US-guided FNA were examined retrospectively. Clustered microcalcifications did not undergo biopsy with this method. Patients who underwent follow-up excisional biopsy or mammography with a duration of at least 24 months were included in the study.

RESULTS

In all, 117 lesions met criteria for inclusion, of which 85 (73%) were diagnosed as benign at cytopathologic evaluation and underwent mammographic follow-up of at least 24 months (range, 24-67 months; mean, 36 months). Thirty-two lesions (27%) had either malignant or atypical cytopathologic findings, for which surgery was recommended. Eleven (9%) of the 32 had malignant cytopathologic findings from initial US-guided FNA, which were confirmed at surgical excision. The remaining 21 lesions (18%) were diagnosed as atypical on the basis of US-guided FNA results. Of these, 18 lesions underwent excisional biopsy: Two were diagnosed as carcinoma (not otherwise specified), and 16 were diagnosed with a variety of benign disorders. The remaining three patients with atypical lesions chose mammographic follow-up rather than surgical diagnosis, and their conditions have remained stable for more than 24 months. Of the 85 benign cases, one changed during follow-up (12 months) and underwent repeat biopsy, with malignancy noted. The sensitivity of US-guided FNA in identifying malignant lesions was 93% (13 of 14), and the specificity of a benign finding was 100% (102 of 102). The positive and negative predictive values of US-guided FNA supported by on-site cytopathologic evaluation were 100% (13 of 13) and 99% (102 of 103), respectively.

CONCLUSION

Supported by appropriately trained on-site cytopathologists and in conjunction with follow-up mammography, US-guided FNA appears to be efficacious in the management of patients with abnormal radiographic findings. It is quick, relatively inexpensive, and minimally invasive, and, in the presence of competent cytopathologists, should be the modality of choice.