Progressive Loss of Function in a Limb Enhancer during Snake Evolution.

The evolution of body shape is thought to be tightly coupled to changes in regulatory sequences, but specific molecular events associated with major morphological transitions in vertebrates have remained elusive. We identified snake-specific sequence changes within an otherwise highly conserved long-range limb enhancer of Sonic hedgehog (Shh). Transgenic mouse reporter assays revealed that the in vivo activity pattern of the enhancer is conserved across a wide range of vertebrates, including fish, but not in snakes. Genomic substitution of the mouse enhancer with its human or fish ortholog results in normal limb development. In contrast, replacement with snake orthologs caused severe limb reduction. Synthetic restoration of a single transcription factor binding site lost in the snake lineage reinstated full in vivo function to the snake enhancer. Our results demonstrate changes in a regulatory sequence associated with a major body plan transition and highlight the role of enhancers in morphological evolution. PAPERCLIP.

The little skate genome and the evolutionary emergence of wing-like fins.

Skates are cartilaginous fish whose body plan features enlarged wing-like pectoral fins, enabling them to thrive in benthic environments1,2. However, the molecular underpinnings of this unique trait remain unclear. Here we investigate the origin of this phenotypic innovation by developing the little skate Leucoraja erinacea as a genomically enabled model. Analysis of a high-quality chromosome-scale genome sequence for the little skate shows that it preserves many ancestral jawed vertebrate features compared with other sequenced genomes, including numerous ancient microchromosomes. Combining genome comparisons with extensive regulatory datasets in developing fins-including gene expression, chromatin occupancy and three-dimensional conformation-we find skate-specific genomic rearrangements that alter the three-dimensional regulatory landscape of genes that are involved in the planar cell polarity pathway. Functional inhibition of planar cell polarity signalling resulted in a reduction in anterior fin size, confirming that this pathway is a major contributor to batoid fin morphology. We also identified a fin-specific enhancer that interacts with several hoxa genes, consistent with the redeployment of hox gene expression in anterior pectoral fins, and confirmed its potential to activate transcription in the anterior fin using zebrafish reporter assays. Our findings underscore the central role of genome reorganization and regulatory variation in the evolution of phenotypes, shedding light on the molecular origin of an enigmatic trait.

Pathogenic Aß production by heterozygous PSEN1 mutations is intrinsic to the mutant protein and not mediated by conformational hindrance of wild-type PSEN1.

Presenilin-1 (PSEN1) is the catalytic subunit of the intramembrane protease γ-secretase and undergoes endoproteolysis during its maturation. Heterozygous mutations in the PSEN1 gene cause early-onset familial Alzheimer's disease (eFAD) and increase the proportion of longer aggregation-prone amyloid-ß peptides (Aß42 and/or Aß43). Previous studies had suggested that PSEN1 mutants might act in a dominant-negative fashion by functional impediment of wild-type PSEN1, but the exact mechanism by which PSEN1 mutants promote pathogenic Aß production remains controversial. Using dual recombinase-mediated cassette exchange (dRMCE), here we generated a panel of isogenic embryonic and neural stem cell lines with heterozygous, endogenous expression of PSEN1 mutations. When catalytically inactive PSEN1 was expressed alongside the wild-type protein, we found the mutant accumulated as a full-length protein, indicating that endoproteolytic cleavage occurred strictly as an intramolecular event. Heterozygous expression of eFAD-causing PSEN1 mutants increased the Aß42/Aß40 ratio. In contrast, catalytically inactive PSEN1 mutants were still incorporated into the γ-secretase complex but failed to change the Aß42/Aß40 ratio. Finally, interaction and enzyme activity assays demonstrated the binding of mutant PSEN1 to other γ-secretase subunits, but no interaction between mutant and wild-type PSEN1 was observed. These results establish that pathogenic Aß production is an intrinsic property of PSEN1 mutants and strongly argue against a dominant-negative effect in which PSEN1 mutants would compromise the catalytic activity of wild-type PSEN1 through conformational effects.

The cellular landscape of the endochondral bone during the transition to extrauterine life.

The cellular complexity of the endochondral bone underlies its essential and pleiotropic roles during organismal life. While the adult bone has received significant attention, we still lack a deep understanding of the perinatal bone cellulome. Here, we have profiled the full composition of the murine endochondral bone at the single-cell level during the transition from fetal to newborn life and in comparison with the adult tissue, with particular emphasis on the mesenchymal compartment. The perinatal bone contains different fibroblastic clusters with blastema-like characteristics in organizing and supporting skeletogenesis, angiogenesis and hematopoiesis. Our data also suggest dynamic inter- and intra-compartment interactions, as well as a bone marrow milieu that seems prone to anti-inflammation, which we hypothesize is necessary to ensure the proper program of lymphopoiesis and the establishment of central and peripheral tolerance in early life. Our study provides an integrative roadmap for the future design of genetic and cellular functional assays to validate cellular interactions and lineage relationships within the perinatal bone.

Enhancer redundancy provides phenotypic robustness in mammalian development.

Distant-acting tissue-specific enhancers, which regulate gene expression, vastly outnumber protein-coding genes in mammalian genomes, but the functional importance of this regulatory complexity remains unclear. Here we show that the pervasive presence of multiple enhancers with similar activities near the same gene confers phenotypic robustness to loss-of-function mutations in individual enhancers. We used genome editing to create 23 mouse deletion lines and inter-crosses, including both single and combinatorial enhancer deletions at seven distinct loci required for limb development. Unexpectedly, none of the ten deletions of individual enhancers caused noticeable changes in limb morphology. By contrast, the removal of pairs of limb enhancers near the same gene resulted in discernible phenotypes, indicating that enhancers function redundantly in establishing normal morphology. In a genetic background sensitized by reduced baseline expression of the target gene, even single enhancer deletions caused limb abnormalities, suggesting that functional redundancy is conferred by additive effects of enhancers on gene expression levels. A genome-wide analysis integrating epigenomic and transcriptomic data from 29 developmental mouse tissues revealed that mammalian genes are very commonly associated with multiple enhancers that have similar spatiotemporal activity. Systematic exploration of three representative developmental structures (limb, brain and heart) uncovered more than one thousand cases in which five or more enhancers with redundant activity patterns were found near the same gene. Together, our data indicate that enhancer redundancy is a remarkably widespread feature of mammalian genomes that provides an effective regulatory buffer to prevent deleterious phenotypic consequences upon the loss of individual enhancers.

The Shh/Gli3 gene regulatory network precedes the origin of paired fins and reveals the deep homology between distal fins and digits.

One of the central problems of vertebrate evolution is understanding the relationship among the distal portions of fins and limbs. Lacking comparable morphological markers of these regions in fish and tetrapods, these relationships have remained uncertain for the past century and a half. Here we show that Gli3 functions in controlling the proliferative expansion of distal progenitors are shared among dorsal and paired fins as well as tetrapod limbs. Mutant knockout gli3 fins in medaka (Oryzias latipes) form multiple radials and rays, in a pattern reminiscent of the polydactyly observed in Gli3-null mutant mice. In limbs, Gli3 controls both anterior-posterior patterning and cell proliferation, two processes that can be genetically uncoupled. In situ hybridization, quantification of proliferation markers, and analysis of regulatory regions reveal that in paired and dorsal fins, gli3 plays a main role in controlling proliferation but not in patterning. Moreover, gli3 down-regulation in shh mutant fins rescues fin loss in a manner similar to how Gli3 deficiency restores digits in the limbs of Shh mutant mouse embryos. We hypothesize that the Gli3/Shh gene pathway preceded the origin of paired appendages and was originally involved in modulating cell proliferation. Accordingly, the distal regions of dorsal fins, paired fins, and limbs retain a deep regulatory and functional homology that predates the origin of paired appendages.

Rapid or Immediate ART, HIV Stigma, Medical Mistrust, and Retention in Care: An Exploratory Mixed Methods Pilot Study.

Rapid or immediate antiretroviral therapy (iART) after HIV diagnosis improves linkage to care and time to viral suppression. However, iART may affect or be affected by HIV-related stigma and medical mistrust. In this mixed-methods pilot study, we examined the bi-directional role of HIV stigma, medical mistrust, and visit adherence (VA) in the context of iART in a diverse, newly diagnosed patient population. Participants were recruited from an HIV clinic in New York City and we utilized a convergent parallel design integrating quantitative data from demographic surveys, the HIV Stigma Survey (HIVSS), the Medical Mistrust Index (MMI) and electronic medical records, and qualitative data from in-depth interviews. Among the sample (N = 30), 26% (N = 8) initiated ART same-day or within 3 days, while the majority (N = 17) initiated between 4 and 30 days, and 17% (N = 5) initiated ART > 30 days. The median (range) age was 35, and most were English-speaking, Black or Hispanic men and identified as gay. Time to ART initiation was associated with time to linkage to care and time to viral suppression. Day 0-3 group's major theme was iART as stigma prevention, and they had the highest mean HIVSS, lowest MMI score, and a visit adherence of 0.86. Day 4-30 group's major theme was alleviation of internalized stigma, and they had the lowest mean HIVSS score, and highest visit adherence of 0.91. Day > 30 group's major theme was exacerbation of perceived or anticipated stigma, had the highest MMI score and a visit adherence of 0.85. iART implementation requires equitable strategies that address HIV-stigma and mistrust.

Development of a workflow for the detection of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis from rectal swabs using the spectra VRE medium.

BACKGROUND: Spectra™ VRE agar (Remel, Lenexa, KS) is a chromogenic agar that is FDA approved for screening patients for VRE colonization. The package insert recommends confirming isolates with identification and susceptibility testing, but confirming every culture delays time to result. Given the agar's historic high specificity for E. faecium isolates, we theorized the agar could be utilized as a stand-alone screening to minimize reagents and time. AIM: Our laboratory sought to develop a workflow to optimize the use of the medium. METHODS: We plated 3,815 rectal swabs to the Spectra VRE agar and compared results to traditional identification and susceptibility testing. RESULTS: Dark blue or purple colonies on the agar demonstrated a sensitivity of 98% and specificity of 85% for detection of VRE faecium, but light blue colonies were significantly less specific for E. faecalis. CONCLUSIONS: We streamlined our workflow to accept dark blue or purple colonies as VRE faecium and plan to perform additional testing only on light blue colonies. Interestingly, higher quantity of growth increased the accuracy of the agar. In the future, growth quantity may be used to further streamline the workflow once more data is obtained.

Transgender Women's Experiences Using SMARTtest, a Smartphone Application to Facilitate Self- and Partner-HIV/Syphilis Testing Using the INSTI Multiplex.

We present experiences of transgender women (TW) who have sex with men with SMARTtest, a smartphone app to accompany the INSTI Multiplex®, a one-minute, dual blood-based HIV/syphilis rapid test. TW participants (N = 11) received 10 INSTI Multiplex® tests to take home for self- and/or partner-testing and installed the SMARTtest app on their phones. The SMARTtest app aimed to support INSTI Multiplex users in correctly performing the test, interpreting the results, and connecting with care following a positive HIV or syphilis screening. After 3 months, users completed in-depth interviews on their experiences. A total of 9 TW used SMARTtest with partners. App feedback was positive, but refining is necessary. Specifically, TW reported that SMARTtest is easy to use and convenient; instructions on how to use the INSTI Multiplex presented on the app were helpful to complete procedures correctly; the most frequently used feature on SMARTtest was the information on clinics that offered confirmatory testing; and participants and their partners were not concerned about app privacy but reported that this could change if INSTI Multiplex detected an HIV-positive result. Further, participants provided recommendations on how to improve SMARTtest, and changes were mostly related to features, content, functionality, navigation, and overall "look" of the app. SMARTtest is promising to facilitate INSTI Multiplex® use in TW. User feedback should be integrated in future versions.

RepeatsDB in 2021: improved data and extended classification for protein tandem repeat structures.

The RepeatsDB database (URL: https://repeatsdb.org/) provides annotations and classification for protein tandem repeat structures from the Protein Data Bank (PDB). Protein tandem repeats are ubiquitous in all branches of the tree of life. The accumulation of solved repeat structures provides new possibilities for classification and detection, but also increasing the need for annotation. Here we present RepeatsDB 3.0, which addresses these challenges and presents an extended classification scheme. The major conceptual change compared to the previous version is the hierarchical classification combining top levels based solely on structural similarity (Class > Topology > Fold) with two new levels (Clan > Family) requiring sequence similarity and describing repeat motifs in collaboration with Pfam. Data growth has been addressed with improved mechanisms for browsing the classification hierarchy. A new UniProt-centric view unifies the increasingly frequent annotation of structures from identical or similar sequences. This update of RepeatsDB aligns with our commitment to develop a resource that extracts, organizes and distributes specialized information on tandem repeat protein structures.

Acceptability and Use of a Dual HIV/Syphilis Rapid Test and Accompanying Smartphone App to Facilitate Self- and Partner-Testing Among Cisgender Men and Transgender Women Who Have Sex with Men.

At home self- and partner-testing may reduce HIV and syphilis transmission by detecting undiagnosed infections. Forty-eight cisgender men and transgender women who men who have sex with men were given ten INSTI Multiplex kits and downloaded the SMARTtest app to facilitate self- and partner testing over the next three months. Thirty-seven (77%) participants self-tested using the INSTI (mean = 3.7 times, SD = 3.9); 26 (54%) tested partners (mean = 1.6 times, SD = 2.2). Participants liked the test for its ease of use, quick results, and dual HIV/syphilis testing but its blood-based nature hindered use with partners. Participants with reactive syphilis results always attributed them to a past infection and these results presented a challenge to testing with partners and the ability to accurately assess risk of infection. Most participants stated they would use the INSTI for self-testing (100%) and for partner-testing (89%). Acceptability of the SMARTtest app was high for functionality (M = 4.16 of max 5, SD = 0.85) and helpfulness (M = 6.12 of max 7, SD = 1.09). Participants often used the app as needed, eschewing its use if they felt comfortable conducting the test and interpreting its results. Seventy-eight percent would recommend the app to a friend. Availability of the INSTI Multiplex as a self-test with the accompanying SMARTtest app might increase frequency of HIV and syphilis testing, allowing for earlier detection of infection and reduced transmission.

RESUMEN: El uso de pruebas rápidas caseras con parejas y como auto-pruebas puede reducir la transmisión del VIH y la sifilis al detectar infecciones no diagnosticadas. Cuarenta y ocho hombres cisgénero y mujeres transgénero que tienen sexo con hombres recibieron diez kits del INSTI Multiplex y descargaron la aplicación SMARTtest para facilitar su uso con parejas y para auto-pruebas durante los próximos tres meses. Treinta y siete (77%) participantes se auto-testearon utilizando el INSTI (media = 3.7 veces, DE = 3.9); 26 (54%) testearon a sus parejas (media = 1.6 veces, DE = 2.2). A los participantes les gustó la prueba por su facilidad de uso, rapidez de los resultados y por ser una prueba dual de VIH/sífilis, pero al ser una prueba basada en sangre dificultó su uso con parejas. Los participantes con resultados de sífilis reactivos siempre atribuyeron éstos a una infección pasada y sus resultados presentaron un desafío para el uso de pruebas con parejas. La mayoría de los participantes afirmaron que utilizarían el INSTI como auto-pruebas (100%) y para testear a sus parejas (89%). La aceptabilidad de la aplicación SMARTtest fue alta para la funcionalidad (M = 4.16 de un máximo de 5, SD = 0.85) y utilidad (M = 6.13 de un máximo de 7, SD = 1.09). Los participantes solían utilizar la aplicación según fuera necesario, evitando su uso si se sentían cómodos realizando la prueba e interpretando sus resultados. El 78% recomendaría la aplicación a un amigo. La disponibilidad del INSTI Multiplex como auto-prueba con la aplicación SMARTtest podría aumentar la frecuencia de las pruebas de VIH y sífilis, lo que permite una detección más temprana de la infección y reduce la transmisión.

Infrequent STI Testing in New York City Among High Risk Sexual and Gender Minority Individuals Interested In Self- and Partner-Testing.

Testing for sexually transmitted infections (STIs) remains low among sexual and gender minority populations. We assessed STI testing history using a retrospective survey among 129 HIV-negative cisgender men who have sex with men (cMSM) and transgender women who have sex with men (tWSM) who were at high risk for STI acquisition. All participants were enrolled in a parent study on self- and partner-testing for HIV and syphilis, and reported condomless anal intercourse with multiple partners during the prior 3 months. We additionally used bivariate tests to evaluate participants' STI testing by their history of using pre-exposure prophylaxis (PrEP). One-in-seven respondents (n = 18) reported having never tested for an STI, one-quarter (n = 33) had not tested in the past year, and two-thirds (n = 83) had never used PrEP. PrEP-naïve respondents were less likely to report recent STI testing (47% vs. 85%). "Routine doctor's visit" was the most prevalent reason for testing, but was less common among PrEP-naïve respondents (83% vs. 100%). Testing was remarkably low given the sample's high risk of HIV and STI infection. Findings suggest that STI testing is more frequent among those who have ever used PrEP, but the risk of selection bias warrants evaluation in a larger probability sample.

Experiences of Transgender Women Who Used a Dual HIV/Syphilis Rapid Self-test to Screen Themselves and Potential Sexual Partners (the SMARTtest Study).

HIV/syphilis self- and partner-testing may be especially appropriate for transgender women, since they shoulder a disproportionate burden of HIV, other STIs (e.g., syphilis), and report high levels of medical mistrust. The SMARTest study enrolled N = 50 sexual and gender minority individuals. The present analysis aims to understand the experiences (via in-depth interviews) of a subset of n = 11 transgender women who used INSTI Multiplex®, a combination HIV/syphilis rapid self-test, on themselves and potential sex partners. Participants reported that many partners were willing to test, and reported no testing-related violence. Most participants completed tests successfully, though gaining comfort with blood collection took time. There were no HIV-positive tests in this study; one participant and two partners reported a positive syphilis screening. All sought care. Our sample was small and results should be interpreted with caution, but indicate potential future directions for conducting research on self- and partner-testing among transgender women.

Negotiating Use of a Blood-Based, Dual HIV and Syphilis Test with Potential Sexual Partners Among a Sample of Cisgender Men and Transgender Women Who Have Sex with Men in New York City.

Cisgender men who have sex with men (cMSM) and transgender women (TGW) are disproportionally burdened by HIV. Among these populations, HIV partner-testing is a highly acceptable harm reduction tool. Particularly, cMSM and TGW report a stronger preference for blood-based tests that include assays for multiple STIs. However, no existing research has explored how these populations negotiate blood-based testing with sexual partners. In the SMARTtest study, 48 sexually active cMSM and TGW took home dual, blood-based HIV/Syphilis kits for self- and partner-testing. After 3 months, they completed a follow-up assessment and in-depth interviews about their experiences initiating testing. Of the 42 responding participants, 27 (64%) reported that it had been "fairly" or "very easy" to raise the idea of testing with partners. Participants predominantly employed partner-conscious communication strategies, including framing the testing proposal as a mandatory, non-personal component of their participation in a research study, gradually incorporating testing mentions into discussions about sexual health, and using the kits to facilitate joint testing. Yet, 21 (44%) participants reported having sex with at least one partner they did not ask to test. Concern regarding partner reactions emerged as a significant barrier to discussing test use; similarly, many partners were averse to taking a blood-based test in the context of a casual sexual encounter. Nonetheless, these findings suggest that dual, blood-based HIV/STI rapid tests may represent acceptable harm reduction tools among similar populations of cMSM and TGW, particularly if future partner-testing research is broadened to consider key couples' dynamics that may impact test usage.

Paraneoplastic autoimmune autonomic ganglionopathy as the first symptom of bladder cancer: a case report and review of literature.

BACKGROUND: Autoimmune autonomic ganglionopathy is a rare, immune-mediated disorder associated with anti-ganglionic α3-subunit nicotinic acetylcholine receptor (anti-α3gAChR) antibodies, which bind to acetylcholine receptor in autonomic ganglia (parasympathetic and sympathetic) leading to autonomic failure. This disorder is mostly associated with viral infections, but it can also be associated with systemic malignancies. Here, we report the case of a paraneoplastic autonomic ganglionopathy as the first symptom of bladder cancer. METHOD: Case report. RESULTS: A 47-year-old man, without medical history of interest, stated to the emergency department for progressive blurry vision with eye and mouth dryness, constipation, and dizziness upon standing for the last 2 weeks. Orthostatic hypotension was demonstrated by a drop in 13.3 mmHg mean blood pressure (BP) from supine (100/60 mmHg) to 45° reclining sitting position (80/50 mmHg). Blood tests, chest X-ray, brain MRI, and electroneuronography were unremarkable. Electrochemical skin conductance was reduced. Serological examination was positive for anti-α3gAChR antibodies. A full-body CT scan revealed a bladder tumor, which was treated by transurethral bladder resection. The pathologic study demonstrated a low-grade non-muscle-invasive bladder urothelial carcinoma. After tumor resection, and treatment with intravenous immunoglobulins and corticoids, a gradually improvement was observed. Today, the patient remains asymptomatic. CONCLUSION: Subacute panautonomic failure can be the first symptom for systemic malignancies. This case reports a paraneoplastic autonomic ganglionopathy as the first symptom of bladder cancer. This case highlights the importance of a systemic study to rule out the presence of cancer when autoimmune autonomic ganglionopathy is present.

Agricultural pesticide residues in water from a karstic aquifer in Yucatan, Mexico, pose a risk to children's health.

Yucatan is a region with a high impact of water contamination since it has a karst type soil favoring contaminants entry into the phreatic level, the only source of freshwater in the area. However, no studies report pesticides in water for human consumption or the risk it represents. The objective of this study was to detect and measure pesticide concentrations in domestic tap water to estimate the risk (carcinogenic and non-carcinogenic) to health. A non-probabilistic sampling was applied of 48 tap water sources, and then pesticide detection with solid-phase extraction gas chromatography coupled to the electron capture and flame photometric detectors allowed the estimation of risk through hazard ratios. The present results suggest that aldrin, heptachlor, and ß-BHC residues in domestic tap water from Ticul, Yucatan, pose a risk to children's health, particularly for potential carcinogenic risks.

CEREBELLAR COGNITIVE AFFECTIVE SYNDROME IMPROVEMENT WITH SELECTIVE INHIBITOR OF SEROTONIN RECAPTATION.

Cerebellar cognitive affective syndrome (CCAS) is characterized by alterations at the cognitive level (dysexecutive syndrome, visuospatial deficit, language ...), associated with affective / emotional changes.

Experiences Receiving HIV-Positive Results by Phone: Acceptability and Implications for Clinical and Behavioral Research.

Improving HIV testing rates and increasing early detection among men who have sex with men (MSM) are critical strategies for enhancing overall health and decreasing HIV transmission. Remote testing and phone delivery of HIV test results may reduce barriers such as geographic isolation or HIV-related stigma. In 2018-19, 50 MSM completed qualitative interviews about their experience receiving a positive HIV test result via phone through their participation in a research study that included remote HIV testing. Interview topics included the acceptability of, and concerns about, phone delivery of HIV results, as well as suggestions for improvement. Interviews were transcribed, coded, and analysed using an inductive thematic approach. Overall, participants reported high acceptability of phone delivery of HIV-positive results. Participants praised the support and information provided by study staff. Benefits identified included increased convenience compared to in-person medical visits, allowing participants to emotionally process their test results privately, as well as receiving the results from supportive and responsive staff members. A few participants indicated drawbacks to phone-based HIV test result delivery, such as logistical concerns about receiving a phone call during the day (e.g., while at work), reduced confidentiality, and the lack of in-person emotional support. Overall, participants described phone delivery of positive HIV-results as acceptable. At-home testing with phone delivery has the potential to increase HIV testing access, especially to geographically isolated or medically underserved patients.

Transgender Women's Barriers, Facilitators, and Preferences on Tailored Injection Delivery Strategies to Administer Long-Acting Injectable Cabotegravir (CAB-LA) for HIV Pre-exposure Prophylaxis (PrEP).

Long-acting injectable cabotegravir (CAB-LA) is in advanced stages of clinical trials. Under the standard protocol, CAB-LA is injected into the gluteal muscle by a healthcare provider every eight weeks. To explore transgender women's barriers and facilitators to tailored delivery strategies-including self-injection and injection in "drop-in" centers-we completed in-depth interviews with N = 15 transgender women in New York City. Participants endorsed the alternative delivery methods and the corresponding features we proposed, and expressed likes and dislikes about each. These fell into the following categories: competence (e.g., the person delivering CAB-LA must have skills to do so), convenience (e.g., CAB-LA must be easy to obtain), and privacy or fear of judgement (e.g., participants did not want to feel judged for using CAB-LA by providers or other service consumers). Findings suggest the need to offer CAB-LA to transgender women through multiple delivery protocols.

Use of Rapid HIV Self-Test to Screen Potential Sexual Partners: Results of the ISUM Study.

ISUM ("I'll show you mine") was a randomized controlled trial in which 272 transgender women and men who have sex with men in New York, NY (NYC) and San Juan, Puerto Rico (SJU) were assigned to an intervention group (n = 136), in which they had access to free HIV self-testing (ST) kits, or to a control group (n = 136). The trial aimed to determine whether the intervention group would use ST to screen sexual partners and have fewer condomless anal intercourse (CAI) occasions with serodiscordant or unknown status partners than the control group. The intervention group had on average 10 (32%) fewer CAI occasions; though clinically relevant, this difference fell short of statistical significance (p = .08). In NYC (n = 166) intervention participants had significantly fewer CAI occasions, whereas in SJU (n = 106) they reported non-significantly more CAI occasions. Two devastating hurricanes hit SJU during the study and may have impacted results in unmeasured ways.