Remediation of arsenic- and nitrate-contaminated groundwater through iron-dependent autotrophic denitrifying culture.

Groundwater contamination with arsenic and nitrate poses a pressing concern for the safety of local communities. Bioremediation, utilizing Fe(II)-oxidizing nitrate reducing bacteria, shows promise as a solution to this problem. However, the relatively weak environmental adaptability of a single bacterium hampers practical application. Therefore, this study explored the feasibility and characteristics of a mixed iron-dependent autotrophic denitrifying (IDAD) culture for effectively removing arsenic and nitrate from synthetic groundwater. The IDAD biosystem exhibited stable performace and arsenic resistance, even at a high As(III) concentration of 800 µg/L. Although the nitrogen removal efficiency of the IDAD biosystem decreased from 71.4% to 64.7% in this case, the arsenic concentration in the effluent remained below the standard (10 µg/L) set by WHO. The crystallinity of the lepidocrocite produced by the IDAD culture decreased with increasing arsenic concentration, but the relative abundance of the key iron-oxidizing bacteria norank_f_Gallionellaceae in the culture showed an opposite trend. Metagenomic analysis revealed that the IDAD culture possess arsenic detoxification pathways, including redox, methylation, and efflux of arsenic, which enable it to mitigate the adverse impact of arsenic stress. This study provides theoretical understanding and technical support for the remediation of arsenic and nitrate-contaminated groundwater using the IDAD culture.

Reverse-transcription, loop-mediated isothermal amplification assay for the sensitive and rapid detection of H10 subtype avian influenza viruses.

BACKGROUND: The H10 subtype avian influenza viruses (H10N4, H10N5 and H10N7) have been reported to cause disease in mammals, and the first human case of H10N8 subtype avian influenza virus was reported in 2013. Recently, H10 subtype avian influenza viruses (AIVs) have been followed more closely, but routine diagnostic tests are tedious, less sensitive and time consuming, rapid molecular detection assays for H10 AIVs are not available. METHODS: Based on conserved sequences within the HA gene of the H10 subtype AIVs, specific primer sets of H10 subtype of AIVs were designed and assay reaction conditions were optimized. A reverse-transcription loop-mediated isothermal amplification (RT-LAMP) assay was established for the rapid detection of H10 subtype AIVs. The specificity was validated using multiple subtypes of AIVs and other avian respiratory pathogens, and the limit of detection (LOD) was tested using concentration gradient of in vitro-transcribed RNA. RESULTS: The established assay was performed in a water bath at 63 °C for 40 min, and the amplification result was visualized directly as well as under daylight reflections. The H10-RT-LAMP assay can specifically amplify H10 subtype AIVs and has no cross-reactivity with other subtypes AIVs or avian pathogens. The LOD of the H10-RT-LAMP assay was 10 copies per µL of in vitro-transcribed RNA. CONCLUSIONS: The RT-LAMP method reported here is demonstrated to be a potentially valuable means for the detection of H10 subtype AIV and rapid clinical diagnosis, being fast, simple, and low in cost. Consequently, it will be a very useful screening assay for the surveillance of H10 subtype AIVs in underequipped laboratories as well as in field conditions.

A loop-mediated isothermal amplification assay for the visual detection of duck circovirus.

BACKGROUND: Duck circovirus (DuCV) infection in farmed ducks is associated with growth problems or retardation syndromes. Rapid identification of DuCV infected ducks is essential to control DuCV effectively. Therefore, this study aims to develop of an assay for DuCV to be highly specific, sensitive, and simple without any specialized equipment. METHODS: A set of six specific primers was designed to target the sequences of the Rep gene of DuCV, and A loop-mediated isothermal amplification (LAMP) assay were developed and the reaction conditions were optimized for rapid detection of DuCV. RESULTS: The LAMP assay reaction was conducted in a 62°C water bath condition for 50 min. Then the amplification products were visualized directly for color changes. This LAMP assay is highly sensitive and able to detect twenty copies of DuCV DNA. The specificity of this LAMP assay was supported by no cross-reaction with other duck pathogens. CONCLUSION: This LAMP method for DuCV is highly specific and sensitive and can be used as a rapid and direct diagnostic assay for testing clinical samples.

Sequencing and phylogenetic analysis of an avian reovirus genome.

Avian reovirus infection causes considerable economic loss to the commercial poultry industry. Live-attenuated vaccine strain S1133 (v-S1133, derived from parent strain S1133) is considered the safest and most effective vaccine and is currently used worldwide. To identify the genes responsible for its attenuation, DNA sequences of open reading frames (ORF) of S1133 and its parent strains S1133, 1733, 526, and C78 along with three field isolates (GuangxiR1, GuangxiR2, and GX110058) and one isolate (GX110116) from a vaccinated chicken were performed. The sequence data were compared with available sequences in nucleotide sequence databases of American (AVS-B, 138, 176) and Chinese (C-98 and T-98) origin. Sequence analysis identified that several v-S1133 specific nucleotide substitutions existed in the ORFs of λA, λB, λC, µA, µB, µNS, σA, σB, and σNS genes. The v-S1133 strain could be differentiated from the field-isolated strains based on single nucleotide polymorphisms. Phylogenetic analysis revealed that v-S1133 shared the highest sequence homologies with S1133 and reovirus isolates from China, grouped together in one cluster. Chinese isolates were clearly more distinct from the American reovirus AVS-B strain, which is associated with runting-stunting syndrome in broilers.

Complete genome sequence analysis of a Newcastle disease virus isolated from a wild egret.

We report here the complete genomic sequence of a novel Newcastle disease virus (NDV) strain, egret/China/Guangxi/2011, isolated from an egret in Guangxi Province, southern China. A phylogenetic analysis based on a fusion gene comparison with different NDV strains revealed that egret/China/Guangxi/2011 was phylogenetically close to genotype VIIa NDV, and the deduced amino acid sequence was (112)R-R-R-K-R-F(117) at the fusion protein cleavage site. The whole nucleotide sequence had the highest homology (93.3%) with the sequence of strain chicken/Sukorejo/019/10 (GenBank accession number HQ697255). This study will help us to understand the epidemiology and molecular characteristics of Newcastle disease virus in a migratory egret.

Complete genome sequence analysis of an H6N1 avian influenza virus isolated from Guangxi pockmark ducks.

We report here the complete genomic sequence of a novel H6N1 avian influenza virus strain, A/Duck/Guangxi/GXd-5/2010(H6N1), isolated from pockmark ducks in Guangxi Province, Southern China. All of the 8 gene segments of A/Duck/Guangxi/GXd-5/2010(H6N1) are attributed to the Eurasian lineage; the amino acid motif of the cleavage site between HA1 and HA2 was P-Q-I-E-T-R-G. These are typical characteristics of the low-pathogenicity avian influenza virus. This study will help to understand the epidemiology and molecular characteristics of avian influenza virus in ducks.

Complete genome sequence analysis of a duck circovirus from Guangxi pockmark ducks.

We report here the complete genomic sequence of a novel duck circovirus (DuCV) strain, GX1104, isolated from Guangxi pockmark ducks in Guangxi, China. The whole nucleotide sequence had the highest homology (97.2%) with the sequence of strain TC/2002 (GenBank accession number AY394721.1) and had a low homology (76.8% to 78.6%) with the sequences of other strains isolated from China, Germany, and the United States. This report will help to understand the epidemiology and molecular characteristics of Guangxi pockmark duck circovirus in southern China.

Detection of antibodies specific to the non-structural proteins of fowl adenoviruses in infected chickens but not in vaccinated chickens.

Antibodies specific to the non-structural proteins of viruses are detected in virus-infected animals and show promise as a reliable diagnostic marker for virus infections. We examined the potential use of two non-structural proteins of fowl adenovirus (FAdV)-based, 100K and 33K, enzyme-linked immunosorbent assays (ELISAs) in the diagnosis of FAdVs. We cloned and expressed the 100K and 33K non-structural protein genes of the FAdVs in the pGEX-4T-1 plasmid vector. Purified 100K and 33K proteins alone or in combination were used as antigens in ELISAs. Antibodies specific to the 100K and 33K non-structural proteins were detected in chickens experimentally infected with FAdVs, but not in chickens vaccinated with inactivated FAdVs. In contrast, the agar gel precipitation (AGP) test detected FAdV-specific antibodies in 70.3% of the vaccinated chickens, suggesting that the non-structural protein-based ELISA could be used in the differential diagnosis of infected and vaccinated chickens. To further validate the 100K and 33K-based ELISA (100K-33K-ELISA) method, we compared its sensitivity and specificity with that of a whole virus-based ELISA and an AGP test in detecting FAdV-specific antibodies in 350 field samples. The results showed that the 100K-33K-ELISA exhibited a higher sensitivity than the AGP test and a comparable sensitivity and specificity to the whole virus ELISA. Overall, the 100K-33K-ELISA method is sensitive, specific and can be used to distinguish an acute FAdV infection from an inactivated virus-based vaccination response.

A duplex quantitative real-time PCR assay for the detection of Haplosporidium and Perkinsus species in shellfish.

A duplex quantitative real-time polymerase chain reaction (dq-PCR) assay was optimized to simultaneously detect Haplosporidium spp. and Perkinsus spp. of shellfish in one reaction. Two sets of specific oligonucleotide primers for Haplosporidium spp. and Perkinsus spp., along with two hydrolysis probes specific for each parasite group, were used in the assay. The dq-PCR results were detected and analyzed using the Light Cycler 2.0 software system. The dq-PCR identified and differentiated the two protozoan parasite groups. The sensitivity of the dq-PCR assay was 200 template copies for both Haplosporidium spp. and Perkinsus spp. No DNA product was amplified when known DNA from Marteilia refringens, Toxoplasma gondii, Bonamia ostreae, Escherichia coli, Cymndinium spp., Mykrocytos mackini, Vibrio parahaemolyticus, and shellfish tissue were used as templates. A total of 840 oyster samples from commercial cultivated shellfish farms from two coastal areas in China were randomly collected and tested by dq-PCR. The detection rate of Haplosporidium spp. was 8.6% in the Qindao, Shandong coastal area, whereas Perkinsus spp. was 8.3% coastal oysters cultivated from shellfish farms of Beihai, Guangxi. The dqPCR results suggested that Haplosporidium spp. was prevalent in oysters from Qindao, Shandong, while Perkinsus spp. was prevalent in oysters from the coastal areas of Beihai, Guangxi. This dq-PCR could be used as a diagnostic tool to detect Haplosporidium spp. and Perkinsus spp. in cultivated shellfish.

Glutathione improves testicular spermatogenesis through inhibiting oxidative stress, mitochondrial damage, and apoptosis induced by copper deposition in mice with Wilson disease.

BACKGROUND AND OBJECTIVE: There are considerable evidence of reproductive impairment in male organisms with Wilson disease (WD). The purpose of this study was to observe spermatogenesis, mitochondrial damage, apoptosis, and the level of oxidative stress in the testes of Wilson disease model TX mice, and to observe the effect and mechanism of glutathione on testicular spermatogenesis. METHODS: Mice were divided into a normal control group (control group), Wilson disease model TX mice group (WD group), penicillamine-treated TX mice group (penicillamine group) and glutathione-treated TX mice group (glutathione group). Testicular coefficient, histomorphology of testis and epididymis, number of spermatozoa, apoptosis of spermatogenic cells and expression of apoptosis-related proteins were observed. Ultrastructural analysis of mitochondria and mitochondrial membrane potential (MMP) monitored using JC-1 dye were used to detect mitochondrial damage. The levels of malondialdehyde (MDA), glutathione (GSH), catalase (CAT), and reactive oxygen species (ROS) in testicular cells were measured to assess oxidative stress. RESULTS: Testicular coefficient did not change in mice with Wilson disease. However, the tissue structure of the testicular seminiferous tubules was damaged, and the number of spermatozoa in the epididymal lumen was significantly reduced in WD group. The apoptosis rate in the testes was significantly increased. The protein expression of the pro-apoptotic proteins Bax and Caspase-3 significantly increased, and the expressions of the anti-apoptotic protein Bcl-2 significantly decreased. The levels of ROS and MDA significantly increased, and the levels of CAT and GSH significantly decreased. Mitochondria with abnormal ultrastructure and the rate of JC-1 positive cells were significantly increased in the WD group. After copper chelation by penicillamine, the structure of the testicular seminiferous tubules and the number of spermatozoa in the epididymal lumen were significantly improved. The number of apoptotic cells was significantly reduced. The levels of Bax and Caspase-3 decreased, and the expression of Bcl-2 increased. The contents of CAT and GSH increased, and the levels of ROS and MDA decreased significantly. The abnormal mitochondria and JC-1 positive cells was significantly decreased. The histomorphology of seminiferous tubules, spermatogenic function, apoptosis rate, apoptosis-related proteins, mitochondrial damage, and oxidative stress in Wilson disease TX mice significantly improved after glutathione treatment. CONCLUSION: Copper deposition in Wilson disease can lead to oxidative stress injury, mitochondrial damage, and apoptosis in the testis, leading to the impairment of spermatogenesis. Glutathione may improve testicular spermatogenesis in male Wilson disease TX mice by inhibiting copper deposition-induced oxidative stress, mitochondrial damage, and apoptosis.

High-efficiency all fluorescence white OLEDs with high color rendering index by manipulating excitons in co-host recombination layers.

All fluorescence white organic light-emitting diodes (WOLEDs) based on thermally activated delayed fluorescence (TADF) emitters are an attractive route to realize highly efficient and high color quality white light sources. However, harvesting triplet excitons in these devices remains a formidable challenge, particularly for WOLEDs involving conventional fluorescent emitters. Herein, we report a universal design strategy based on a co-host system and a cascaded exciton transfer configuration. The co-host system furnishes a broad and charge-balanced exciton generation zone, which simultaneously endows the devices with low efficiency roll-off and good color stability. A yellow TADF layer is put forward as an intermediate sensitizer layer between the blue TADF light-emitting layer (EML) and the red fluorescence EML, which not only constructs an efficient cascaded Förster energy transfer route but also blocks the triplet exciton loss channel through Dexter energy transfer. With the proposed design strategy, three-color all fluorescence WOLEDs reach a maximum external quantum efficiency (EQE) of 22.4% with a remarkable color rendering index (CRI) of 92 and CIE coordinates of (0.37, 0.40). Detailed optical simulation confirms the high exciton utilization efficiency. Finally, by introducing an efficient blue emitter 5Cz-TRZ, a maximum EQE of 30.1% is achieved with CIE coordinates of (0.42, 0.42) and a CRI of 84 at 1000 cd m-2. These outstanding results demonstrate the great potential of all fluorescence WOLEDs in solid-state lighting and display panels.

Development of a reverse transcription loop-mediated isothermal amplification assay for visual detection of avian reovirus.

Avian reovirus (ARV) is an important pathogen of poultry and causes significant economic losses to the poultry industry. To develop a rapid and sensitive method for the surveillance of ARV, a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was established using a set of six primers specific to the S1 gene segment of ARV. The established assay was performed at 62°C for 60 min in a thermal block, and the result was visualized directly under daylight or ultraviolet light. The detection limit of the RT-LAMP assay was 10 fg total RNA, which was 100-fold higher than that of reverse transcriptase polymerase chain reactions. The specificity of the assay was supported by the lack of cross-reaction with other avian pathogens. Furthermore, viral RNAs of field isolates were successfully detected by the assay. Overall, the newly established RT-LAMP assay is simple, rapid, sensitive, specific, and can visually detect ARV without the use of any specialized equipment.

Reverse transcription loop-mediated isothermal amplification assay for rapid detection of Bovine Rotavirus.

BACKGROUND: Bovine rotavirus (BRV) infection is common in young calves. This viral infection causes acute diarrhea leading to death. Rapid identification of infected calves is essential to control BRV successfully. Therefore development of simple, highly specific, and sensitive detection method for BRV is needed. RESULTS: A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed and optimized for rapid detection of BRV. Specific primer sets were designed to target the sequences of the VP6 gene of the neonatal calf diarrhea virus (NCDV) strain of BRV. The RT-LAMP assay was performed in a water bath for 60 minutes at 63°C, and the amplification products were visualized either directly or under ultraviolet light. This BRV specific RT-LAMP assay could detect 3.32 copies of subtype A BRV. No cross-reactions were detected with other bovine pathogens. The ability of RT-LAMP to detect bovine rotavirus was further evaluated with 88 bovine rectal swab samples. Twenty-nine of these samples were found to be positive for BRV using RT-LAMP. The BRV-specific-RT-LAMP results were also confirmed by real-time RT-PCR assay. CONCLUSIONS: The bovine rotavirus-specific RT-LAMP assay was highly sensitive and holds promise as a prompt and simple diagnostic method for the detection of group A bovine rotavirus infection in young calves.

Copper deposition in Wilson's disease causes male fertility decline by impairing reproductive hormone release through inducing apoptosis and inhibiting ERK signal in hypothalamic-pituitary of mice.

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism characterized by liver and central nervous system dysfunction. Considerable evidence suggests that infertility is also very common in male patients with WD, but the exact molecular mechanisms involved remain unknown. In order to further investigate the pathological changes in the hypothalamic-pituitary-testicular (HPT) axis and its mechanisms, mice were divided into the normal control group (NC), WD model TX mice group (WD), dimercaptosuccinic acid-treated TX mice group (DMSA), and pregnant horse serum gonadotropin-treated TX mice group (PMSG). The copper content and morphology of hypothalamus and pituitary tissues, the ultrastructure and apoptosis of hypothalamus neurons and pituitary gonadotropin cells, the serum levels of reproductive hormones, and the pregnancy rate and litter size of the female mice were studied. The expression of apoptosis-related proteins and the phosphorylation of extracellular regulatory protein kinase (ERK) 1/2 in the hypothalamus and pituitary were detected. The results showed that the copper content was significantly increased in the WD group, and the histopathological morphology and ultrastructure of the hypothalamus and pituitary were damaged. The levels of the gonadotropin-releasing hormone, the follicle-stimulating hormone, the luteinizing hormone, and testosterone were significantly decreased. The apoptosis rate in the hypothalamus and pituitary was significantly increased. The expressions of proapoptotic proteins Bax and Caspase-3 were significantly increased, the expression of the anti-apoptotic protein Bcl-2 was significantly decreased, and the phosphorylation level of ERK1/2 was significantly decreased. Fertility is significantly reduced. After DMSA intervention, the hypothalamus tissue copper content decreased, the hypothalamus and pituitary tissue morphology and ultrastructure were improved, cell apoptosis was alleviated, the expression of Bax and Caspase-3 was significantly decreased, the expression of Bcl-2 was significantly increased, and the reproductive hormone level, phosphorylation level, and fertility were increased. Fertility was preserved after treatment with PMSG in male TX mice. These results suggest that copper deposition in WD causes male fertility decline by impairing reproductive neuroendocrine hormone release through inducing apoptosis and inhibiting the ERK signal in the hypothalamic-pituitary region. This study can also provide reference for the damage of copper pollution to the male reproductive system.

Visual detection of H3 subtype avian influenza viruses by reverse transcription loop-mediated isothermal amplification assay.

BACKGROUND: Recent epidemiological investigation of different HA subtypes of avian influenza viruses (AIVs) shows that the H3 subtype is the most predominant among low pathogenic AIVs (LPAIVs), and the seasonal variations in isolation of H3 subtype AIVs are consistent with that of human H3 subtype influenza viruses. Consequently, the development of a rapid, simple, sensitive detection method for H3 subtype AIVs is required. The loop-mediated isothermal amplification (LAMP) assay is a simple, rapid, sensitive and cost-effective nucleic acid amplification method that does not require any specialized equipment. RESULTS: A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed to detect the H3 subtype AIVs visually. Specific primer sets target the sequences of the hemagglutinin (HA) gene of H3 subtype AIVs were designed, and assay reaction conditions were optimized. The established assay was performed in a water bath for 50 minutes, and the amplification result was visualized directly as well as under ultraviolet (UV) light reflections. The detection limit of the RT-LAMP assay was 0.1pg total RNA of virus, which was one hundred-fold higher than that of RT-PCR. The results on specificity indicated that the assay had no cross-reactions with other subtype AIVs or avian respiratory pathogens. Furthermore, a total of 176 clinical samples collected from birds at the various live-bird markets (LBMs) were subjected to the H3-subtype-specific RT-LAMP (H3-RT-LAMP). Thirty-eight H3 subtype AIVs were identified from the 176 clinical samples that were consistent with that of virus isolation. CONCLUSIONS: The newly developed H3-RT-LAMP assay is simple, sensitive, rapid and can identify H3 subtype AIVs visually. Consequently, it will be a very useful screening assay for the surveillance of H3 subtype AIVs in underequipped laboratories as well as in field conditions.

Rapid detection of group I avian adenoviruses by a loop-mediated isothermal amplification.

A loop-mediated isothermal amplification (LAMP) assay was optimized for the rapid detection of Group I avian adenoviruses. A set of six primers was designed from the DNA sequences of hexon genes from Group I avian adenovirus. The assay was performed in a water bath for 60 min at 63 C, and the amplification result was visualized by adding a fluorescence dye reagent or by inspecting the white sediment. The results showed that the LAMP assay could detect all 12 serotypes of Group I avian adenovirus and nine Guangxi Group I avian adenovirus isolates. This avian adenovirus Group I-specific LAMP assay could detect 238 copies of avian adenovirus. No cross-reactions were detected using the LAMP assay with avian adenoviruses type II and III or with other avian viruses. The ability of LAMP to detect Group I avian adenovirus isolates was further evaluated with 184 cloacal swab samples from poultry. In total, 72 out of 184 cloacal swab samples from poultry were identified as positive by LAMP, whereas 45 out of 184 were identified as positive by conventional PCR test. The Group I avian adenovirus specific LAMP results were further confirmed by real-time PCR. This specific LAMP method holds promise as a rapid and specific diagnostic assay for detection of samples from birds suspected of adenovirus infection.

Survey of low pathogenic avian influenza viruses in live poultry markets in Guangxi Province, Southern China, 2016-2019.

Low pathogenic avian influenza viruses (LPAIVs) have been widespread in poultry and wild birds throughout the world for many decades. LPAIV infections are usually asymptomatic or cause subclinical symptoms. However, the genetic reassortment of LPAIVs may generate novel viruses with increased virulence and cross-species transmission, posing potential risks to public health. To evaluate the epidemic potential and infection landscape of LPAIVs in Guangxi Province, China, we collected and analyzed throat and cloacal swab samples from chickens, ducks and geese from the live poultry markets on a regular basis from 2016 to 2019. Among the 7,567 samples, 974 (12.87%) were LPAIVs-positive, with 890 single and 84 mixed infections. Higher yearly isolation rates were observed in 2017 and 2018. Additionally, geese had the highest isolation rate, followed by ducks and chickens. Seasonally, spring had the highest isolation rate. Subtype H3, H4, H6 and H9 viruses were detected over prolonged periods, while H1 and H11 viruses were detected transiently. The predominant subtypes in chickens, ducks and geese were H9, H3, and H6, respectively. The 84 mixed infection samples contained 22 combinations. Most mixed infections involved two subtypes, with H3 + H4 as the most common combination. Our study provides important epidemiological data regarding the isolation rates, distributions of prevalent subtypes and mixed infections of LPAIVs. These results will improve our knowledge and ability to control epidemics, guide disease management strategies and provide early awareness of newly emerged AIV reassortants with pandemic potential.

Orbital- and millennial-scale Antarctic Circumpolar Current variability in Drake Passage over the past 140,000 years.

The Antarctic Circumpolar Current (ACC) plays a crucial role in global ocean circulation by fostering deep-water upwelling and formation of new water masses. On geological time-scales, ACC variations are poorly constrained beyond the last glacial. Here, we reconstruct changes in ACC strength in the central Drake Passage in vicinity of the modern Polar Front over a complete glacial-interglacial cycle (i.e., the past 140,000 years), based on sediment grain-size and geochemical characteristics. We found significant glacial-interglacial changes of ACC flow speed, with weakened current strength during glacials and a stronger circulation in interglacials. Superimposed on these orbital-scale changes are high-amplitude millennial-scale fluctuations, with ACC strength maxima correlating with diatom-based Antarctic winter sea-ice minima, particularly during full glacial conditions. We infer that the ACC is closely linked to Southern Hemisphere millennial-scale climate oscillations, amplified through Antarctic sea ice extent changes. These strong ACC variations modulated Pacific-Atlantic water exchange via the "cold water route" and potentially affected the Atlantic Meridional Overturning Circulation and marine carbon storage.

Response to Comment on "A global environmental crisis 42,000 years ago".

Our study on the exact timing and the potential climatic, environmental, and evolutionary consequences of the Laschamps Geomagnetic Excursion has generated the hypothesis that geomagnetism represents an unrecognized driver in environmental and evolutionary change. It is important for this hypothesis to be tested with new data, and encouragingly, none of the studies presented by Picin et al. undermine our model.

Response to Comment on "A global environmental crisis 42,000 years ago".

Our paper about the impacts of the Laschamps Geomagnetic Excursion 42,000 years ago has provoked considerable scientific and public interest, particularly in the so-called Adams Event associated with the initial transition of the magnetic poles. Although we welcome the opportunity to discuss our new ideas, Hawks' assertions of misrepresentation are especially disappointing given his limited examination of the material.