Biology subjects

Kato, T.

Publications and source records attributed to Kato, T..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

Orthogonalization of spontaneous and stimulus-driven activity by hierarchical neocortical areal network in primates

Understanding how biological neural networks perform reliable information processing in the presence of intensive spontaneous activity (1-3) is an essential question in biological computation. Stimulus-evoked and spontaneous activities show orthogonal (dissimilar) patterns in the primary visual cortex (V1) of mice (4-6), which is likely to be beneficial for separating sensory signals from internally generated noise (5, 7-12); however, those in V1 of carnivores and primates show highly similar patterns (3, 13-17). Consequently, the mechanism of segregation of stimulus information and internally generated noise in carnivores and primates remain unclear. To address this question, we used primate-optimized functional imaging (18) to precisely compare spontaneous and stimulus-evoked activities in multiple areas of the marmoset visual cortical pathway (19). In marmoset V1, but not in mouse V1, spontaneous and stimulus-evoked activity shared similar activity patterns, suggesting a function of spontaneous activity specific to mammals with functional columns. However, in the higher-order visual areas of marmosets, spontaneous and stimulus-evoked activities exhibited dissimilar patterns. Analysis of neural activity geometry further revealed progressive orthogonalization of the two types of activities along the cortical hierarchy in marmosets, which reached a level comparable to that of mouse V1. Thus, orthogonalization of spontaneous and stimulus-evoked activity is a general principle of cortical computation, which, in primates, is implemented by the hierarchical areal network.

neuroscience↗

bioRxiv2024

Dimeric assembly of F1-like ATPase for Mycoplasma gliding motility

Rotary ATPases, including F1Fo- and V/A-ATPases, are molecular motors that exhibit rotational movements for energy conversion1. In the gliding bacterium, Mycoplasma mobile, a dimeric F1-like ATPase forms a chain structure with the glycolytic enzyme, phosphoglycerate kinase (PGK), within the cell2, which is proposed to drive the bacterial gliding motility2-4. However, the mechanisms of force generation and transmission remain unclear. Here, we present a 3.2 [A] resolution structure of the dimeric ATPase complex obtained using electron cryomicroscopy (cryo-EM). Notably, the structure revealed an assembly distinct from that of known dimeric forms of F1Fo-ATPase5, despite containing conserved F1-ATPase structures. The two ATPase units were interconnected by GliD dimers, previously identified as MMOB16202,6. Gli{beta}, a homologue of the F1-ATPase catalytic subunit6, exhibited a specific N-terminal region that incorporates PGK into the complex. Structural conformations of the catalytic subunits, catalytically important residues, and nucleotide-binding pattern of the catalytic sites of the ATPase displayed strong similarities to F1-ATPase, suggesting a rotation based on the rotary catalytic mechanism conserved in rotary ATPases1,7-10. Overall, the cryo-EM structure underscores an evolutionary connection in the rotary ATPases and provides insights into the mechanism through which F1-like ATPase drives bacterial gliding motility.

microbiology↗

bioRxiv2024

Accurate localization of cortical and subcortical sources of M/EEG signals by a convolutional neural network with a realistic head conductivity model: Validation with M/EEG simulation, evoked potentials, and invasive recordings

While electroencephalography (EEG) and magnetoencephalography (MEG) are well-established non-invasive methods in neuroscience and clinical medicine, they suffer from low spatial resolution. Particularly challenging is the accurate localization of subcortical sources of M/EEG, which remains a subject of debate. To address this issue, we propose a four-layered convolutional neural network (4LCNN) designed to precisely locate both cortical and subcortical source activity underlying M/EEG signals. The 4LCNN was trained using a vast dataset generated by forward M/EEG simulations based on a realistic head volume conductor model. The 4LCNN implicitly learns the characteristics of M/EEG and their sources from the training data without need for explicitly formulating and fine-tuning optimal priors, a common challenge in conventional M/EEG source imaging techniques. We evaluated the efficacy of the 4LCNN model on a validation dataset comprising forward M/EEG simulations and two types of real experimental data from humans: 1) somatosensory evoked potentials recorded by EEG, and 2) simultaneous recordings from invasive electrodes implanted in the brain and MEG signals. Our results demonstrate that the 4LCNN provides robust and superior estimation accuracy compared to conventional M/EEG source imaging methods, aligning well with established neuroscience knowledge. Notably, the accuracy of the subcortical regions was as accurate as that of the cortical regions. The 4LCNN method, as a data-driven approach, enables accurate source localization of M/EEG signals, including in subcortical regions, suggesting future contributions to various research endeavors such as contributions to the clinical diagnosis, understanding of the pathophysiology of various neuronal diseases and basic brain functions.

neuroscience↗

bioRxiv2024

Structural analysis of S-ring composed of FliFG fusion proteins in marine Vibrio polar flagellar motors

The marine bacterium Vibrio alginolyticus possesses a polar flagellum driven by a sodium ion flow. The main components of the flagellar motor are the stator and rotor. The C-ring and MS-ring which are composed of FliG and FliF, respectively, are parts of the rotor. Here, we purified an MS-ring composed of FliF-FliG fusion proteins and solved the near-atomic resolution structure of the S-ring--the upper part of the MS-ring--using cryo-electron microscopy. This is the first report of an S-ring structure from Vibrio whereas, previously, only those from Salmonella have been reported. The Vibrio S-ring structure reveals novel features compared to that of Salmonella such as tilt angle differences of the core domain and the {beta}-collar region, the decrease of the inter-subunit interaction between core domains, and altered electrostatic inner-surface. The residues potentially interact with other flagellar components, such as FliE and FlgB, are well structurally conserved in Vibrio S-ring. These comparisons clarified the conserved and non-conserved structural features of the MS-ring across different species. IMPORTANCEUnderstanding the structure and function of the flagellar motor in bacterial species is essential for uncovering the mechanisms underlying bacterial motility and pathogenesis. Our study revealed the structure of the Vibrio S-ring, a part of its polar flagellar motor, and highlighted its unique features compared with the well-studied Salmonella S-ring. The observed differences in the inter-subunit interactions and in the tilt angles between the Vibrio and Salmonella S-rings highlighted the species-specific variations in the flagellar assembly. By concentrating on the region where the S-ring and the rod proteins interact, we uncovered conserved residues essential for the interaction. Our research contributes to advancing of bacterial flagellar biology.

biophysics↗

bioRxiv2024

Accelerating antimalarial drug discovery with a new high-throughput screen for fast-killing compounds

The urgent need for rapidly acting compounds in the development of antimalarial drugs underscores the significance of such compounds in overcoming resistance issues and improving patient adherence to antimalarial treatments. The present study introduces a high-throughput screening (HTS) approach using 1536-well plates, employing Plasmodium falciparum lactate dehydrogenase (PfLDH) combined with nitroreductase (NTR) and fluorescent probes to evaluate inhibition of the growth of the asexual blood stage of malaria parasites. This method was adapted to efficiently measure the parasite reduction ratio (PRR) in a 384-well plate format, streamlining the traditionally time-consuming screening process. By successfully screening numerous compounds, this approach identified fast-killing hits early in the screening process, addressing challenges associated with artemisinin-based combination therapies. The high-throughput PRR method is expected to be of value in continuously monitoring fast-killing properties during structure-activity relationship studies, expediting the identification and development of novel, rapidly acting antimalarial drugs within phenotypic drug discovery campaigns.

microbiology↗

bioRxiv2024

Structural and Dynamic Insights into the Biased Signaling Mechanism of the Human Kappa Opioid Receptor

The {kappa}-opioid receptor (KOR) is a member of the G protein-coupled receptor (GPCR) family, responsible for modulating cellular responses through transducers such as G proteins and arrestins. G protein-biased KOR agonists hold promise due to their potential to mitigate side effects such as drug aversion and sedation while preserving analgesic and antipruritic effects. Here, we shed light on the structural dynamics of the human KOR-Gi signaling complex bound with either nalfurafine (a G-protein-biased agonist) or U-50,488H (a balanced agonist) using cryo-electron microscopy (cryo-EM). Cryo-EM structures of the KOR-Gi signaling complexes identify the ligand binding mode in the activated state. Vibrational spectroscopy analysis reveals changes in the ligand-binding pocket upon binding to these ligands. Cell-based mutant experiments pinpoint four amino acids (K2275.40, C2866.47, H2916.52, and Y3127.34; Ballesteros-Weinstein numbering is shown in superscript) that play crucial roles in arrestin recruitment. Among these four amino acids, H2916.52 and Y3127.34 are also implicated in G-protein coupling. Our findings pave the way for targeting specific residues in the KOR ligand-binding pocket to enhance KOR-mediated therapeutic effects while mitigating unwanted side effects.

biophysics↗

bioRxiv2024

Cryo-EM inspired NMR analysis reveals a pH-induced conformational switching mechanism for imparting dynamics to Betanodavirus protrusions

Nervous necrosis virus (NNV), a non-enveloped betanodavirus, causes neuropathies and retinopathies in farmed fish, damaging aquaculture worldwide. NNV has 60 conspicuous surface protrusions comprising the protrusion domain (P-domain) of its capsid protein. Although NNV protrusions play critical roles in infectivity, the underlying dynamics remain unclear. Our cryogenic electron microscopy (cryo-EM)-derived structures of Dragon grouper (Epinephelus lanceolatus) NNV reveal that the protrusions undergo low-pH-induced compaction and movement. We show that the P-domain is monomeric in solution at a pH germane to infection (7.0). Moreover, nuclear magnetic resonance (NMR) structures reveal a peptide (amino acids 311-330) that adopts a flexible loop to form an open pocket. NMR spectral analysis at pH 5.0 aided by molecular dynamics (MD) simulations show that this loop switches to a {beta}-strand under acidic conditions, eliciting pocket closure and P-domain trimerization, highlighting a unique pH-sensing feature. Our docking analysis revealed the N-terminal moiety of sialic acid inserted into and interacting with conserved residues in the pocket. Additionally, a low-pH-induced conformational change in the linker region via peptide bond isomerization conferred malleability on the protrusions. Our work uncovers the protrusion dynamics of a betanodavirus governing its infectivity through a pH-dependent conformational switching mechanism, providing insights into complex virus-host interactions.

biochemistry↗

bioRxiv2023

Use of phase plate cryo-EM reveals conformation diversity of therapeutic IgG with 50 kDa Fab fragment resolved below 6 angstrom

While cryogenic electron microscopy (cryo-EM) is fruitfully used for harvesting high-resolution structures of sizable macromolecules, its application to small or flexible proteins composed of domains like immunoglobulin (IgG) remain challenging. Here, we applied single particle cryo-EM to Rituximab, a therapeutic IgG mediating cancer cell toxicity, to explore its solution conformations. We found Rituximab molecules exhibited aggregates in cryo-EM specimens contrary to its solution behavior, and utilized a non-ionic detergent to successfully disperse them as isolated particles amenable to single particle analysis. As the detergent adversely reduced the protein-to-solvent contrast, we employed phase plate contrast to mitigate the impaired protein visibility. Assisted by phase plate imaging, we obtained a canonical three-arm IgG structure with other structures displaying variable arm densities co-existing in solution, affirming high flexibility of arm-connecting linkers. Furthermore, we showed phase plate imaging enables reliable structure determination of Fab to sub-nanometer resolution from ab initio, yielding a characteristic two-lobe structure that could be unambiguously docked with crystal structure. Our findings revealed conformation diversity of IgG and demonstrated phase plate was viable for cryo-EM analysis of small proteins without symmetry. This work helps extend cryo-EM boundaries, providing a valuable imaging and structural analysis framework for macromolecules with similar challenging features.

biochemistry↗

bioRxiv2023

Reduced ornamentation became elaborated in benign environments in a bird species

Many empirical studies have focused on highly-ornamented species to identify ecological factors that maintain the ornamentation or favour its exaggeration. By contrast, although reduction or loss of ornamentation appears to be widespread, species with reduced/lost ornamentation and its relationship with ecological factors are rarely focused on. Here, based on data collected over four years, we studied outermost tail feather length, i.e. a well-known sexual ornamentation in this clade, in relation to roosting location in the Pacific swallow Hirundo tahitica during winter. In contrast to congeners, this species has inconspicuous tail ornamentation, i.e. very shallowly forked tails with vestigial streamers, providing a rare opportunity to study the ecological factors driving reduced ornamentation. We found that Pacific swallows mainly roost in old nests under bridges over rivers, which resemble their original roosting sites, but some roost in old nests under the eaves of houses above the ground. Individuals roosting under the eaves of houses had significantly longer outermost (but not central) tail feathers than those roosting under bridges. Individuals roosting under the eaves of houses were heavier and showed lower physiological stress, and thus might better endure the maintenance cost, favouring ornament elaboration. Because we controlled for the effects of sex and age, these factors would not confound the observed pattern. Reduced ornamentation, as found in Pacific swallows roosting under their original roosting sites, could become elaborated in benign environments (i.e., under eaves, here), stressing the importance of balance between the costs and benefits of ornamentation.

ecology↗

bioRxiv2023

A stress sensor IRE1α is required for bacterial exotoxin-induced inflammasome activation in tissue-resident macrophages

Cholera toxin (CT), a bacterial exotoxin composed of one A subunit (CTA) and five B subunits (CTB), functions as an immune adjuvant. CTB can induce production of interleukin-1{beta} (IL-1{beta}), a proinflammatory cytokine, in synergy with a lipopolysaccharide (LPS), from resident peritoneal macrophages (RPMs) through the pyrin and NLRP3 inflammasomes. However, how CTB or CT activates these inflammasomes in the macrophages has been unclear. Here, we clarified the roles of IRE1, an endoplasmic reticulum (ER) stress sensor, in CT-induced IL-1{beta} production from RPMs. In RPMs, CTB is incorporated into ER and induced ER stress responses, depending on GM1, a cell membrane ganglioside. IRE1-deficient RPMs showed a significant impairment of CT- or CTB-induced IL-1{beta} production, indicating that IRE1 was required for CT- or CTB-induced IL-1{beta} production from RPMs. This study first demonstrates the critical roles of IRE1 in activation of both NLRP3 and pyrin inflammasomes in tissue-resident macrophages. One sentence summaryIRE1 is required for NLRP3 and pyrin-mediated IL-1{beta} production

immunology↗

bioRxiv2023

Cryo-EM of cytoskeletal 'fibril' protein involved in Spiroplasma swimming

Spiroplasma, parasitic or commensal bacteria, can swim by switching the handedness of its helical cell body. A helical cell body is formed by an internal ribbon of MreB, an actin superfamily, and Spiroplasma-specific fibril proteins. Here we have solved the structure of the fibril filament by single-particle cryo-electron microscopy at 3.6 [A] resolution and built its atomic structure. The structure is composed of repeated rings and cylinders. The N-terminal cylinder of the fibril protein shows a structure similar to that of S-adenosylhomocysteine nucleosidase, while the C-terminal ring does not show similarity to other proteins. The filament is nonpolar and flexible, possessing a helical pitch of 700 nm, consistent with cell helicity. Cryo-electron tomography revealed aligned several MreB filaments in the center of the ribbon, flanked by membrane-binding fibril filaments through electrostatic interactions. This study discusses the evolution and roles of the fibril filament.

microbiology↗

bioRxiv2023

Dopamine receptor type 2-expressing medium spiny neurons in the ventral lateral striatum have a non-REM sleep-induce function

Dopamine receptor type 2-expressing medium spiny neurons (D2-MSNs) in the medial part of the ventral striatum (VS) induce non-REM (NREM) sleep from the wake state in animals. However, it is unclear whether D2-MSNs in the lateral part of the VS (VLS), which is anatomically and functionally different from the medial part of the VS, contribute to sleep-wake regulation. This study aims to clarify whether and how D2- MSNs in the VLS are involved in sleep-wake regulation. Our study found that specifically removing D2-MSNs in the VLS led to an increase in wakefulness time in mice during the dark phase using a diphtheria toxin-mediated cell ablation/dysfunction technique. D2-MSN ablation throughout the VS increased dark phase wakefulness time. These findings suggest that VLS D2-MSNs may induce sleep during the dark phase with the medial part of the VS. Next, our fiber photometric recordings revealed that the population intracellular calcium (Ca2+) signal in the VLS D2-MSNs increased during the transition from wake to NREM sleep. The mean Ca2+ signal level of VLS D2-MSNs was higher during NREM and REM sleep than during the wake state, supporting their sleep-inducing role. Finally, optogenetic activation of the VLS D2-MSNs during the wake state always induced NREM sleep, demonstrating the causality of VLS D2-MSNs activity with sleep-induction. Additionally, activation of the VLS D1-MSNs, counterparts of D2-MSNs, always induced wake from NREM sleep, indicating a wake- promoting role. In conclusion, VLS D2-MSNs could have an NREM sleep-inducing function in coordination with those in the medial VS. Significant statementThe sleep-inducing function of D2-MSNs in the medial part of the ventral striatum (VS) has been previously reported; however, their function in the lateral part of the VS (VLS) has not been elucidated. We demonstrated that the diphtheria toxin-induced ablation of D2-MSNs in the VLS, as well as in the entire VS, increased wakefulness time in mice during the dark phase. VLS D2-MSNs had higher average Ca2+ signals during NREM and REM sleep than wake state via fiber photometric recording. Furthermore, optogenetic activation of VLS D2-MSNs during wake state induced NREM sleep in mice. In conclusion, D2-MSNs in the VLS have an NREM sleep-inducing function in coordination with those in the medial VS.

neuroscience↗

bioRxiv2023

An engineered ACE2 decoy broadly neutralizes Omicron subvariants and shows therapeutic effect in SARS-CoV-2-infected cynomolgus macaques

The Omicron variant continuously evolves under the humoral immune pressure obtained by vaccination and SARS-CoV-2 infection and the resultant Omicron subvariants exhibit further immune evasion and antibody escape. Engineered ACE2 decoy composed of high-affinity ACE2 and IgG1 Fc domain is an alternative modality to neutralize SARS-CoV-2 and we previously reported its broad spectrum and therapeutic potential in rodent models. Here, we show that engineered ACE2 decoy retains the neutralization activity against Omicron subvariants including the currently emerging XBB and BQ.1 which completely evade antibodies in clinical use. The culture of SARS-CoV-2 under suboptimal concentration of neutralizing drugs generated SARS-CoV-2 mutants escaping wild-type ACE2 decoy and monoclonal antibodies, whereas no escape mutant emerged against engineered ACE2 decoy. As the efficient drug delivery to respiratory tract infection of SARS-CoV-2, inhalation of aerosolized decoy treated mice infected with SARS-CoV-2 at a 20-fold lower dose than the intravenous administration. Finally, engineered ACE2 decoy exhibited the therapeutic efficacy for COVID-19 in cynomolgus macaques. Collectively, these results indicate that engineered ACE2 decoy is the promising therapeutic strategy to overcome immune-evading SARS-CoV-2 variants and that liquid aerosol inhalation can be considered as a non-invasive approach to enhance efficacy in the treatment of COVID-19.

microbiology↗

bioRxiv2022

Development of a 1:1-binding biparatopic anti-TNFR2 antagonist by epitope selection

Conventional bivalent antibodies against cell surface receptors often initiate unwanted signal transduction by crosslinking two antigen molecules. Biparatopic antibodies (BpAbs) bind to two different epitopes on the same antigen, thus altering crosslinking ability. In this study, we developed BpAbs against tumor necrosis factor receptor 2 (TNFR2), which is an attractive immune checkpoint target. Using different pairs of variable regions specific to topographically distinct TNFR2 epitopes, we successfully regulated the size of BpAb-TNFR2 immunocomplexes to result in controlled agonistic activities. One particular antagonist BpAb bound TNFR2 in 1:1 ratio without unwanted signal transduction, with its structural basis revealed by cryo-electron microscopy. This antagonist suppressed the proliferation of regulatory T cells expressing TNFR2. Therefore, the BpAb format would be useful in designing specific and distinct antibody functions.

biochemistry↗

bioRxiv2022

A Checking Model of Obsessive-Compulsive Disorder Based on the Hypothalamic Defensive System Against a Potential Threat

BACKGROUNDObsessive-compulsive disorder (OCD) is a psychiatric disorder characterized by obsessive thoughts and compulsive behavior. While some theories imply that OCD patients have cognitive biases and dysfunctional motivation regarding a potential threat, these views are not adequately supported by neurological evidence. Hypothalamic perifornical (PeF) urocortin-3 (UCN3) neurons are involved in defensive responses to a potential threat, and the activation of these neurons in mice induces repetitive and excessive checking and burying of novel objects. In this study, we evaluated the hypothesis that mice in which PeF UCN3 neurons are activated can serve as an OCD model. METHODSPeF UCN3 neurons were chemogenetically activated with clozapine-N oxide (CNO) in Ucn3-Cre mice. Marble-burying activity, repetitive/stereotypic behaviors in the homecage, and excessive responses to a novel object were measured as OCD-like behaviors. The effects of clinically used drugs for treating OCD on these behaviors were evaluated. The effect of CNO on neural activity in the cortico-striato-thalamo-cortical loop (which is regarded as an OCD circuit) was assessed with c-Fos immunolabeling. RESULTSCNO increased marble-burying activity, evoked homecage-specific repetitive/stereotypic behaviors that probably aimed to seal entrances, and induced repetitive and excessive checking and burying of novel objects. These behaviors were suppressed by selective serotonin-reuptake inhibitors but not by diazepam. CNO increased neural activity in the cortico-striato-thalamo-cortical loop. CONCLUSIONSThese results indicated that mice whose PeF UCN3 neurons are activated can serve as a model of OCD, particularly as a checking model. This supports theories concerning the role of potential threats in the pathophysiology of OCD.

animal behavior and cognition↗

bioRxiv2022

Structural basis of Irgb6 inactivation by Toxoplasma gondii through the phosphorylation of switch I.

Upon infection with Toxoplasma gondii, host cells produce immune-related GTPases (IRGs) to kill the parasite. T. gondii counters this response by releasing ROP18 kinase, which inactivates IRG GTPases and inhibits their recruitment to the T. gondii parasitophorous vacuole (PV). However, the molecular mechanisms of this process are entirely unknown. Here we report the atomic structures of Irgb6 with a phosphomimetic mutation by ROP18. The mutant has lower GTPase activity and is not recruited to the PV membrane (PVM). The crystal structure shows the mutant exhibit a distinct conformation from the physiological nucleotide-free form, thus preventing GTPase cycling. This change allosterically modifies the conformation of the membrane-binding interface, preventing physiological PVM-binding. Docking simulation of PI5P also supports the impaired binding of the mutant to PVM. We thus demonstrate the structural basis for T. gondii escape from host cell-autonomous defense, and provide a structural model for regulating enzymatic activity by phosphorylation.

microbiology↗

bioRxiv2022

Three-dimensional motions of GroEL during substrate protein recognition

GroEL is a bacterial chaperonin responsible for the assisted folding of non-native and misfolded polypeptides into biologically active proteins. The adaptive nature of the recognition mechanism of chaperonins toward client polypeptides inherently lends itself to structural heterogeneity, which hampers detailed analyses of intermolecular recognition and binding. In this report, we used single-particle cryo-EM and multiple rounds of focused mask three-dimensional classification to reveal a landscape of distinct snapshots of endogenous GroEL complexed with an unfolded substrate, the water-soluble domain of human UDP glucuronosyltransferase 1A (UGT1A), at 2.7-3.5 [A] resolution. We demonstrate that UGT1A occupies the GroEL ring asymmetrically, engaging with 2-3 contiguous subunits and that a subunit bound to UGT1A exhibits a wider range of conformational dynamics, consistent with AlphaFold models. These data reveal molecular motions during initial substrate capture at near-atomic detail.

biophysics↗

bioRxiv2022

Estimation of the reference lead (Pb) concentration levels affecting immune cells in the blood of Black-headed Gulls (Chroicocephalus ridibundus, Laridae)

The biological effects of lead (Pb) contamination have been reported in various species. There are no restrictions on the use of Pb products, including bullets, in the areas south of Hokkaido, Japan. Local governments have announced the presence of some Pb in the soil sediments of water bodies. Previous studies have confirmed the relationship between blood Pb level (BLL) and immune cells. This study was performed with the aim of clarifying the effect of Pb contamination on immune cells. In total, 170 Black-headed Gulls (Chroicocephalus ridibundus) were captured, including a population in Tokyo Bay between November 2018 and April 2021 and a population in Mikawa Bay between January 2019 and April 2021. Linear regression analysis was performed with the white blood cell count (WBC), proportion of heterophils (Het), proportion of lymphocytes (Lym), ratio of heterophils and lymphocytes (H/L ratio), copy number of CD4 messenger RNA, and copy number of CD8 messenger RNA as the objective variables, and the BLL as the explanatory variable. The group with BLL < 1.0 g/dL had a significantly lower Het and higher Lym than that with BLL > 3.5 g/dL (P < 0.05). In addition, the group with BLL < 1.0 g/dL had a significantly lower H/L ratio than that with BLL > 3.5 g/dL. CD8 and WBC were higher in the group with the group with BLL range, from 1.0 to 3.5 g/dL than those in the group with BLL < 1.0 g/dL. This study suggests that the effect of Pb pollution on the immune cells of Black-headed Gulls is lower than some previous criteria values.

ecology↗