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Biology subjects

Khalid, N.

Publications and source records attributed to Khalid, N..

8 recordsLinked to original sources

Few-Shot Classification of C. elegans Developmental Stages via Explainable Hierarchical Hyperbolic Graph Embeddings

Automated, accurate, and fast developmental-stage classification of C. elegans from microscopy-based morphological images is essential for aging research, drug screening, and disease modeling. However, it remains challenging due to morphological similarities between stages and the limited annotated data. In this work, we propose HyperDev, a hyperbolic few-shot learning framework that addresses these limitations by directly encoding developmental hierarchies in the embedding space, unlike conventional Euclidean approaches that treat stages as independent classes. HyperDev uses Poincare ball geometry, combined with a biologically informed developmental prior, to naturally represent stage relationships. We introduce our self-curated C. elegans dataset spanning seven developmental stages (Egg, L1-L4, Adult, Dauer) with extreme class imbalance (6-8 samples per minority class). HyperDev achieves competitive classification accuracy (76.9-88.3%) while providing intrinsic explainability across nine 7-way few-shot evaluation settings. The learned embeddings exhibited strong biological alignment (Pearson r = 0.669, p < 0.001), while significantly outperforming ProtoNet (r = 0.187), MatchingNet (r = 0.235), and RelationNet (r = 0.464). These results establish hyperbolic geometry as a principled approach to explainable few-shot learning in biological imaging, where understanding learned representations is as critical as predictive performance. Clinical RelevanceBy enabling explainable, data-efficient developmental staging from scarce samples, HyperDev supports improved phenotype quantification for aging research, disease modeling, and drug screening.

bioinformatics↗

High-Throughput Profiling of Bacterial Respiration Using the Resipher Reveals Functional Responses to Nutrients and Antibiotics

Oxygen consumption is a direct functional readout of bacterial respiration and metabolic state, yet existing methods for quantifying oxygen dynamics are limited in throughput and temporal resolution. Here, we establish a high-throughput platform for real-time profiling of bacterial respiration by adapting the Resipher, a non-invasive oxygen quantification system, for use in bacterial cultures. Measurements obtained with the Resipher were comparable to those generated using a Clark-type electrode-based high-resolution respirometer, validating its quantitative accuracy. Across Gram-negative (Escherichia coli, Francisella novicida) and Gram-positive (Enterococcus faecalis, Staphylococcus aureus) species, the Resipher generated reproducible measurements under both growth-permissive and growth-limited conditions, enabling assessment of respiration, independent of proliferation. Functional profiling revealed that oxygen consumption responds dynamically to nutrient availability and electron transport chain perturbation, including species-specific inhibition by benzarone. Notably, oxygen consumption profiles distinguished bactericidal and bacteriostatic antibiotics, with bactericidal agents transiently increasing respiration and bacteriostatic agents suppressing metabolic activity. Together, these findings establish oxygen consumption as a sensitive physiological readout and highlight the potential utility of respiratory profiling for mechanistic studies.

microbiology↗

Selective inhibition of respiratory complex I reveals a bioenergetic vulnerability in Francisella

F. tularensis is a highly infectious Gram-negative bacterial pathogen that causes tularemia, a re-emerging zoonosis of public health concern. Here we identify respiratory complex I as a selective vulnerability in Francisella and define the mechanism of action of a pyrazole compound, tolfenpyrad, with species-specific antibacterial activity. Using F. novicida as a surrogate model, we demonstrated that tolfenpyrad selectively inhibits growth with no measurable effect on E. coli or P. aeruginosa. Tolfenpyrad rapidly suppressed oxygen consumption, depleted ATP, collapsed proton motive force, and induced reactive oxygen species, indicating disruption of bacterial metabolism. Biochemical assays demonstrated selective inhibition of NADH-dependent respiration and membrane-associated NADH oxidation, whereas succinate-driven respiration was unaffected. Moreover, the alternative NADH dehydrogenase (ndh) was not required for tolfenpyrad activity. Structural docking identified a potential tolfenpyrad-binding pocket within the membrane subunit NuoM. These findings reveal species-specific inhibition of Francisella complex I and establish respiratory metabolism as a promising antimicrobial target in these bacteria.

microbiology↗

Pathogenicity determinant protein E is a Francisella type VI secretion system effector protein that modulates host death

Francisella tularensis is a highly pathogenic Gram-negative intracellular bacterial pathogen and the etiologic agent of tularemia, a fatal zoonotic disease that poses a threat to global public health. F. tularensis virulence is mediated by genes on the Francisella pathogenicity island (FPI), which encodes a unique contractile secretion apparatus with functional and structural similarity to bacterial type VI secretion systems (T6SSs). T6SSs can inject effector proteins into host cells to facilitate invasion, intracellular proliferation, and pathogenesis; however, the identity and function of Francisella effectors are still unclear. In this study, we measured T6SS activity in a series of FPI deletion mutants to identify genes that are required for core apparatus activity. We found that Pathogenicity Determinant Protein E (PdpE) is not required for secretion of T6SS substrates or intramacrophage growth. Instead, PdpE forms a complex with another T6SS-secreted effector, PdpC, and limits death of infected host cells by attenuating the macrophage type I interferon response. Importantly, a {Delta}pdpE mutant more rapidly induces death in an established invertebrate in vivo model for Francisella infection. These data define the role of a previously uncharacterized substrate of the Francisella T6SS and provide new insights into host-Francisella interaction.

microbiology↗

Segment Anything for Microscopy

We present Segment Anything for Microscopy, a tool for interactive and automatic segmentation and tracking of objects in multi-dimensional microscopy data. Our method is based on Segment Anything, a vision foundation model for image segmentation. We extend it by training specialized models for microscopy data that significantly improve segmentation quality for a wide range of imaging conditions. We also implement annotation tools for interactive (volumetric) segmentation and tracking, that speed up data annotation significantly compared to established tools. Our work constitutes the first application of vision foundation models to microscopy, laying the groundwork for solving image analysis problems in these domains with a small set of powerful deep learning architectures.

bioinformatics↗

CRISPRi-mediated down-regulation of the cinnamate-4-hydroxylase (C4H) gene enhances the flavonoid biosynthesis in Nicotiana tabacum

Flavonoids are an important class of natural compounds present in plants. However, despite various known biological activities and therapeutic potential, the low abundance of flavonoids in nature limits their development for industrial applications. In this study, we aimed to enhance flavonoid production by silencing cinnamate-4-hydroxylase (C4H), an enzyme involved in the branch point of the flavonoid biosynthetic pathway, using the clustered regularly interspaced short palindromic repeats interference (CRISPRi) approach. We designed three sgRNAs targeting the promoter region of NtC4H and cloned them into a CRISPRi construct. After introducing into Nicotiana tabacum cell suspension culture, the transformed cells were sampled for qPCR and liquid chromatography-mass spectrometry analyses. Sixteen of 21 cell lines showed PCR-positive, confirming the presence of CRISPRi transgene. The NtC4H transcript in the transgenic cells was 0.44-fold lower than in the wild-type. In contrast, the flavonoid-related genes at the other branching pathway, such as Nt4CL and NtCHS, in the C4H-silenced cells showed a higher expression than wild-type. The upregulation of these genes increased their respective products, including pinostrobin, naringenin, and chlorogenic acid. This study provides valuable insight into the future development of CRISPRi-based metabolic engineering to suppress target genes in plants.

plant biology↗

Genome assembly and analysis of the flavonoid and phenylpropanoid biosynthetic pathways in Fingerroot ginger (Boesenbergia rotunda)

Boesenbergia rotunda (Zingiberaceae), is a high-value culinary and ethno-medicinal plant of Southeast Asia. The rhizomes of this herb have high flavanone and chalcone content. Here we report genome analysis of B. rotunda together with a complete genome sequence as a hybrid assembly. B. rotunda has an estimated genome size of 2.4 Gb which was assembled as 27,491 contigs with N50 size of 12.386 Mb. The highly heterozygous genome encodes 71,072 protein-coding genes and has 72% repeat content, with class I TEs occupying [~]67% of the assembled genome. Fluorescence In Situ Hybridization of the 18 chromosome pairs at metaphase showed six sites of 45S rDNA and two sites of 5S rDNA. SSR analysis identified 238,441 gSSRs and 4,604 EST-SSRs with 49 SSR markers common among related species. Genome-wide methylation percentages ranged from 73% CpG, 36% CHG and 34% CHH in leaf to 53% CpG, 18% CHG and 25% CHH in embryogenic callus. Panduratin A biosynthetic unigenes were most highly expressed in watery callus. B rotunda has a relatively large genome with high heterozygosity and TE content. This assembly and data (PRJNA71294) comprise a source for further research on the functional genomics of B. rotunda, the evolution of the ginger plant family and the potential genetic selection or improvement of gingers.

genomics↗

Increased levels of the mitochondrial import factor Mia40 prevent the aggregation of polyQ proteins in the cytosol

The formation of protein aggregates is a hallmark of neurodegenerative diseases. Observations on patient material and model systems demonstrated links between aggregate formation and declining mitochondrial functionality, but the causalities remained unclear. We used yeast as model system to analyze the relevance of mitochondrial processes for the behavior of an aggregation-prone polyQ protein derived from human huntingtin. Induction of Q97-GFP rapidly leads to insoluble cytosolic aggregates and cell death. Although this aggregation impairs mitochondrial respiration only slightly, it interferes with efficient import of mitochondrial precursor proteins. Mutants in the import component Mia40 are hypersensitive to Q97-GFP. Even more surprisingly, Mia40 overexpression strongly suppresses the formation of toxic Q97-GFP aggregates both in yeast and in human cells. Based on these observations, we propose that the posttranslational import into mitochondria competes with aggregation-prone cytosolic proteins for chaperones and proteasome capacity. Owing to its rate-limiting role for mitochondrial protein import, Mia40 acts as a regulatory component in this competition. This role of Mia40 as dynamic regulator in mitochondrial biogenesis can apparently be exploited to stabilize cytosolic proteostasis. (174/175 words)

biochemistry↗