Biology subjects

Lad, H.

Publications and source records attributed to Lad, H..

11 recordsLinked to original sources

bioRxiv2026

More fruits, more frugivores, but not necessarily more visits: findings from two tropical plant-avian frugivore communities

Fruit resource availability can influence the local abundance of avian frugivores through bottom-up regulation, but whether greater resource availability translates into higher visitation rates to fruiting trees remains poorly understood. Greater fruit availability could increase visitation by supporting larger frugivore populations, or reduce visitation to individual trees if increases in frugivore abundance are not proportionate to those in fruit availability or if frugivores distribute their foraging effort. Understanding these relationships can provide insights into the relative role of abundance and trait-based mechanisms in structuring plant-frugivore communities. We compared fruit availability, avian frugivore abundance, and frugivore visitation rates on fruiting trees across two protected wet tropical forest sites: Anamalai Tiger Reserve in the Western Ghats and Namdapha Tiger Reserve in the Eastern Himalaya. Specifically, we quantified the availability of bird-consumed fruits across one-ha patches, estimated local abundances of major frugivore groups, and tested whether visitation rates on individual fruiting trees were related to frugivore abundance, body mass, and degree of frugivory. We found that small-seeded fruit availability was significantly higher in Anamalai than in Namdapha. Local abundances of several relatively small-bodied frugivore groups, including bulbuls, barbets, fairy-bluebirds, and mynas, were also higher in Anamalai. However, visitation rates of several frugivore groups on individual fruiting trees were higher in Namdapha. Visitation rates across all avian frugivore species were associated with frugivore abundances only in Anamalai, and not associated with body mass or degree of frugivory in either site. Thus, although greater fruit availability was likely associated with higher frugivore abundance, this increase in abundance did not consistently translate into higher visitation rates at individual fruiting trees, which provides some support for the resource dilution hypothesis. Our results highlight the importance of considering fruit resource availability and frugivore abundance when examining variation in tropical plant-frugivore interactions.

ecology↗

bioRxiv2026

Transcriptomic analysis of human induced pluripotent stem cell cardiomyocytes and myocardial tissue reveals novel role for miR-9-5p in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited disease characterized by the thickening of the heart muscle. Mutations in genes encoding contractile proteins, such MYBPC3 and MYH7 account for over half of patients with familial HCM. MicroRNAs (miRNAs) are pivotal regulators of gene expression that may influence disease progression. Despite their potential significance, there is a scarcity of published data on miRNAs in HCM. Induced pluripotent stem cells (iPSCs) have emerged as valuable tools for modeling various cardiovascular diseases, including HCM. However, the miRNA expression profiles associated with HCM remain largely unexplored within iPSC models. Investigating the differential expression of miRNAs in HCM patients offers a promising avenue to identify potential therapeutic targets for individuals affected by this condition. In this study, we performed an unbiased screen using a microarray (NanoString Technologies) that contained 798 miRNAs to identify differentially expressed miRNAs in iPSC-cardiomyocytes (CM) and myocardial tissues derived from healthy donors and HCM patients with MYBPC3 and MYH7 mutations, identifying miR-9-5p as significantly downregulated in all HCM iPSC-CM and myectomy tissue compared to control. KEGG pathway analysis of gene targets using miRTarBase and g:Profiler revealed that miR-9-5p regulates genes in the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance pathway, which is involved in hypercontractility associated with HCM. Modulation of miR-9-5p expression in vitro using mimics significantly reduced cardiomyocyte size and contractility of MYBPC3 mutant iPSC-CMs whereas healthy control iPSC-CMs treated with antagomiRs exhibited hypertrophy. Our findings identify miR-9-5p as a regulator of cardiomyocyte hypertrophy and contractility, and suggest the miR-9-5p/EGFR tyrosine kinase inhibitor resistance axis as a potential therapeutic target to mitigate hypertrophy and hypercontractility exhibited in HCM.

molecular biology↗

bioRxiv2026

Hornbill abundance and habitat correlates in Kali Tiger Reserve, Western Ghats, India-Insights from collaborative monitoring

1.The future of species, particularly large-bodied birds, under climate threats, is increasingly unclear. Protected areas (PAs) can mitigate the impacts of global change, but are not completely immune. This makes it imperative to monitor populations even inside PAs. In the forests of the Western Ghats, three hornbill species are found--Malabar Grey Hornbill, Malabar Pied Hornbill and Great Hornbill. Kali Tiger Reserve, of Karnataka state, India, is known for its healthy hornbill populations, yet few systematic surveys have attempted to estimate their abundance, distributions and habitat affiliations. In this study, we documented the distributions of the three hornbills, estimated the density of Malabar Grey Hornbills and assessed correlates of hornbill encounter rates within the reserve. Malabar Grey Hornbills were the most abundant and widely distributed, found in all ranges of the reserve. Gund, Kadra and Phansoli had the most detections of Malabar Pied and Great Hornbills. Encounter rates of Malabar Grey Hornbill were positively correlated with food-tree stem density, those of Malabar Pied Hornbill negatively correlated with basal area, while those of Great Hornbill not significantly associated with any variable. Malabar Grey Hornbills had a density of 5.1 per km2 (mean flock size = 1.2). While encounter rates of Malabar Pied and Great Hornbills were low, these numbers track the breeding season, when vocal activity is low and females are inside nests. This survey represents a partnership between researchers and the Karnataka forest department, aimed towards inculcating the collaborative spirit of research and monitoring.

ecology↗

bioRxiv2026

Frugivore species richness influences dietary specialisation and network properties in Asian wet tropical forests

AimTo examine how variation in frugivore species richness influences dietary specialisation and the organisation of plant-frugivore interaction networks in tropical forests. LocationSix undisturbed lowland wet tropical forest sites across four biodiversity hotspots in south and south-east Asia. Time period2016-2024. Major taxa studiedAvian frugivores and fleshy-fruited woody plants. MethodsWe recorded plant-avian frugivore interactions across six undisturbed evergreen forest sites spanning a seven-fold gradient in frugivore species richness, while holding forest type and phylogenetic composition broadly comparable. Using over 4,200 hours of focal observations on 551 fruiting plants, we recorded more than 34,000 feeding visits by 138 frugivore species on 133 plant species. We used a) Joint species distribution models to determine the relative influence of fruit and seed traits, and b) network analyses to evaluate how dietary breadth and network properties varied with frugivore species richness. ResultsAcross sites, frugivore visitation was primarily explained by fruit and seed morphology, with seed size accounting for an average of 39.7% of explained variation, followed by fruit width (24.4%), fruit crop size (21.9%), and pulp lipid content (14.1%). Frugivores in species-rich communities exhibited narrower dietary breadth (Pearsons r = -0.87 between normalised degree and species richness). Correspondingly, plant-frugivore networks became less connected and nested, and more modular, with increasing frugivore richness (Pearsons r = -0.9, -0.98, and 0.84, respectively). Main conclusionsIncreasing frugivore species richness intensifies dietary specialisation, which in turn drives changes in plant-frugivore network structure. These findings highlight how local species richness shapes interaction networks through changes in consumer niche breadth, with implications for the organisation of tropical forest mutualistic communities.

ecology↗

bioRxiv2025

Clinical risk factors of intensive care unit acquired weakness predicted by human muscle microtissue response to humoral factors

1.ICUAW is an acquired phenomenon in the critically ill patient that is characterized by severe muscle weakness and atrophy. It results from both myopathic and neuropathic injury and is associated with heightened patient morbidity and mortality. Critical illness survivors exhibit variable functional outcomes following ICUAW, ranging from full recovery to persistent weakness with a significant negative impact on quality of life. Despite clinical importance, the mechanistic understanding of ICUAW remains incomplete, in part due to a paucity of tractable, species-specific experimental models. Previous studies have suggested a potential causative role of bloodborne factors, though this remains a matter of debate. To address these technological and knowledge gaps, we leveraged a 3-D human skeletal muscle microtissue (hMMT) culture platform to investigate the ability of humoral factors to directly impact pathogenesis of the myopathic component of ICUAW; critical illness myopathy (CIM). Blood serum collected from ICU patients within 72 hours of ICU admission was used to treat hMMTs for 6 days starting at a time-point when the myotubes were multinucleated, striated, and capable of generating force. hMMTs treated with serum from patients that survived the ICU stay exhibited several hallmarks of CIM including; significant reductions in myotube diameter (atrophy) and striation density, alongside functional declines in calcium release, peak force, and force kinetics. The in vitro profiles of ICU serum treated hMMTs displayed significant associations with known ICUAW and CIM clinical risk factors (e.g. age, length of ICU stay) such that individual patient risk factors could be predicted from serum-induced hMMT responses. An evaluation of hMMT responses enabled delineation of ICU non-survivors from healthy control and ICU survivors. This study offers an enabling technology for studies of CIM biology in the context of human cells while also delivering compelling evidence that humoral factors directly influence ICU-associated skeletal muscle pathogenesis. Together, these advances may inform strategies for preventing or treating ICUAW.

bioengineering↗

bioRxiv2025

Understudied and underprotected: biodiversity and conservation challenges in the Konkan region of Maharashtra

In biodiversity hotspots, such as the Western Ghats, periodic synthesis of existing ecological research can help identify knowledge gaps and address critical threats to biodiversity. The Maharashtra part of the Konkan region, situated between the Sahyadri foothills and the west coast, with diverse tropical vegetation, harbours unique open ecosystems, such as lateritic plateaus, and supports a multitude of threatened species, including hornbills and tigers. However, the region remains relatively understudied and has not received adequate protection through state or national conservation policies and laws. The area is undergoing rapid human-driven land-use change. These activities can impact the regions biodiversity, necessitating an effort to identify knowledge gaps and critical threats. Through a combination of a literature review and focus group discussions with 44 participants from various institutions and non-governmental organisations, we synthesised existing published information on the Konkan region of Maharashtra and identified key research gaps and conservation challenges. Our review of 138 studies found that while agroforestry and human-wildlife interactions have received some research attention, the effects of climate change on the regions biodiversity remain poorly understood. Focus group discussions highlighted major threats, including land-use changes due to expanding monoculture plantations, clear-felling of forests, forest fires, environmental pollution, and rapid infrastructure development, which are leading to habitat loss and fragmentation. Some of these concerns were validated by publicly available regional data, which revealed a 30% increase in roads, a 14% expansion of cashew plantations, and associated forest loss. This synthesis offers valuable insights for government and non-governmental organisations to inform future research and conservation efforts in the region.

ecology↗

bioRxiv2025

Effects of tree plantations on population and roosting ecology of an endemic agamid lizard in Western Ghats Biodiversity Hotspot

Low-elevation wet tropical forests support herpetofaunal diversity but are increasingly replaced by monoculture tree plantations and have poor Protected Area coverage, leaving herpetofauna vulnerable. Research on how monoculture plantations affect reptile populations remains inconclusive, and the ecology of endemic species in these changing landscapes is poorly understood. We compared densities and roosting ecology of Monilesaurus rouxii, an endemic agamid lizard, across low- and high-elevation forests and cashew and rubber plantations in the Western Ghats Biodiversity Hotspot using nocturnal transects. We found that low-elevation forests, despite poor Protected Area coverage, had significantly higher densities of Monilesaurus rouxii than high-elevation forests and cashew plantations. Roost site use did not differ significantly across the different land-use, indicating roost fidelity. However, Monilesaurus rouxii exhibited ontogenetic shifts in roosting substrate and height. Our findings highlight the conservation importance of unprotected low-elevation forests, which are rapidly being converted to monoculture tree plantations. We show that plantation types may differ in their impacts on reptile populations. We also show the utility of nocturnal transects for population estimation of diurnal lizards.

ecology↗

bioRxiv2025

Effects of frugivore species pool and seed size on the diversity and functional composition of frugivores visiting fruiting trees

The relationship between biodiversity and ecosystem functioning in seed dispersal remains understudied despite its critical role in maintaining plant diversity in the tropics. Field studies on this relationship are often confounded by environmental and phylogenetic variations across species richness gradients. We examined how overall avian frugivore species richness at a site influenced the frugivore richness, visitation rates and functional composition of two key effect traitsbeak width and hand-wing indexon fruiting trees. Across six sites in tropical Asia, spanning a sevenfold gradient in frugivore species richness but with similar forest types and phylogenetically nested frugivore communities, we recorded 34,014 interactions between 134 avian frugivores and 131 plant species. Our results provide some support for the biodiversity-ecosystem functioning relationship, as higher overall frugivore species richness increased the number of frugivore species visiting individual fruiting trees but not the functional composition of frugivores. Seed size had a stronger influence on the frugivore species richness, visitation rates, and the beak size of visiting frugivores, highlighting the dominant role of morphological trait matching in influencing plant-frugivore interactions. Our findings suggest functional redundancy in certain aspects of seed dispersal effectiveness due to density compensation and the presence of key seed disperser lineages in species-poor sites.

ecology↗

bioRxiv2024

Distinct pathogenic influence of anti-HMGCR+ and anti-SRP+ immune-mediated necrotizing myopathy autoantibodies on engineered muscle function

Immune-mediated necrotizing myopathy (IMNM) is a subgroup of idiopathic inflammatory myopathies associated with anti-signal recognition particle (SRP) or anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) autoantibodies. However, the demonstration of a direct pathogenic effect of IMNM patient autoantibodies on skeletal muscle contractile force, independent of the downstream activation of the complement pathway, has yet to be reported. Thus, the goal of this study was to leverage a custom 3D-human skeletal muscle microtissue (hMMT) culture platform, that enables muscle cell contractile apparatus maturation and the analysis of contractile function, to evaluate the direct effect of total immunoglobulins (IgGs) isolated from IMNM patients with amplification of anti-SRP+ or anti-HMGCR+ autoantibodies. hMMTs capable of force generation were treated with total IgGs, isolated from 3 SRP+ and 3 HMGCR+ patients plasma, and delivered in complement inactivated media for 4 days. hMMT health was then evaluated by quantifying the peak force and contraction kinetics in response to electrical field stimulation and by performing histological analysis of sarcomere and myotube structures. Treating hMMTs with total IgGs from anti-HMGCR+ patients resulted in a decline in tetanus contractile force, though sarcomere Z-line architecture analysis revealed no significant influences on sarcomere organization. hMMT treatment with total IgGs from anti-SRP+ patients induced muscle atrophy, observed via significantly smaller myotube diameter, but this did not translate to a decline in contractile function. This study demonstrates that anti-SRP and anti-HMGCR autoantibodies exert direct, but distinct influences on IMNM-associated skeletal muscle pathogenesis, which may inform IMNM therapy development.

bioengineering↗

bioRxiv2024

Effects of land use change and elevation on endemic shrub frogs in a biodiversity hotspot

Agroforestry, often promoted as a sustainable agriculture practice, is rapidly expanding, often at the cost of primary tropical forests. While agroforestry impacts amphibian diversity negatively, its effects on population demography, microhabitat use and body condition are relatively understudied. This information is crucial for determining and promoting amphibian-friendly land use practices. We compared habitats, population densities, microhabitat use, and body condition of two endemic species of shrub frogs (Pseudophilautus amboli and Raorchestes bombayensis) across 1) elevations (low- and high-elevation forests) and 2) land use categories (cashew, rubber, and low-elevation forests) in the northern part of the Western Ghats Biodiversity Hotspot. Using distance sampling, we demonstrated that abundances of the two shrub frog species differed across elevation categories, with Pseudophilautus more common in low-elevation forests and Raorchestes more prevalent in high-elevation forests. Both species of frogs exhibited extremely skewed, male-biased sex ratios, with three females for 100 males. Pseudophilautus had lower densities and poor recruitment and exhibited altered microhabitat use in cashew plantations compared to low-elevation forests. Although adult male Pseudophilautus densities in rubber were similar to those in low-elevation forests, they exhibited altered microhabitat use and smaller body sizes than in forests, indicating poor body condition. We demonstrate differential impacts of agroforestry types on shrub frogs. We also demonstrate that distance sampling can be a useful tool for population monitoring of shrub frogs, which comprise almost 25% of the anuran diversity in the Western Ghats. Additionally, there is a need to identify the drivers of extremely skewed sex ratios, which make these species vulnerable to population crashes. Considering the recent downlisting of the two focal species to Least Concern, we advocate for their uplisting to at least Near Threatened status in light of their patchy distribution, negative impacts of rapidly expanding agroforestry plantations and extremely skewed sex ratios.

ecology↗

bioRxiv2020

Rapid, field-deployable nucleobase detection and identification using FnCas9

Detection of pathogenic sequences or variants in DNA and RNA through a point-of-care diagnostic approach is valuable for rapid clinical prognosis. In recent times, CRISPR based detection of nucleic acids has provided an economical and quicker alternative to sequencing-based platforms which are often difficult to implement in the field. Here, we present FnCas9 Editor Linked Uniform Detection Assay (FELUDA) that employs a highly accurate enzymatic readout for detecting nucleotide sequences, identifying nucleobase identity and inferring zygosity with precision. We demonstrate that FELUDA output can be adapted to multiple signal detection platforms and can be quickly designed and deployed for versatile applications including rapid diagnosis during infectious disease outbreaks like COVID-19.

molecular biology↗