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The Vempalle Formation of the Cuddapah Supergroup consists of a carbonate-siliciclastic unit with extensive mafic sills and dykes in the upper part of the formation, which hosts barite and chrysotile mineralization in a 44 km long SE–NW trending zone between Vempalle and Lingala. The barite mineralization occurs mainly in the Vemula–Velpula area as fracture-fill and breccia-fill veins in mafic dykes that intrude the carbonate of the Vempalle Formation. The barite mineralized mafic rock has undergone extensive hydrothermal alteration, with the primary calcic plagioclase and clinopyroxene replaced by albite and clinochlore, respectively, along with the introduction of secondary epidote, quartz, and calcite, while in the surrounding carbonate, no hydrothermal alteration is observed. The extensive hydrothermal alteration of mineralized mafic rock and large variation in its Ba concentration (68 to 3012 ppm), which generally is abnormally high, indicates that Ba has been scavenged from the mafic rock by fluid-rock reaction. The δ 34 S values of the barite range from +16.19 to +23.24‰, which is comparable to the δ 34 S value of Proterozoic seawater. The characteristics of carbonate and mafic rock indicate that barite mineralization has taken place at shallow crustal depths, where seawater could not be directly involved in the hydrothermal process. Hence, it is inferred that the evolved seawater, i.e., basinal brine, is the source of S. Research highlights Large variation and abnormally high Ba concentration in mafic rocks of the Vempalle Formation in the Cuddapah Basin, together with the extensive hydrothermal alteration present in the mafic rock hosting barite deposit, indicate that Ba was scavenged from the mafic rock through fluid-rock reaction. δ 34 S values of Vempalle barite (+16.19 to +23.24‰) fall within the range estimated for Proterozoic seawater (+10 to +30‰), from which we infer that the primary source of S was seawater.

The mafic sills intruding into the dolostone in the uppermost part of the Vempalle Formation, Cuddapah Supergroup, have caused extensive metasomatism in the dolostone, resulting in serpentinisation and hydrothermal chrysotile mineralisation in the Pulivendla asbestos belt. Three different coloured varieties of serpentine, namely black, green, and yellow serpentine, have developed successively away from the mafic sill-dolostone contact. These serpentines belong to the lizardite variety and occur in the form of massive bands, irregular replacement patches, and stylolite fills in dolostone. Due to high XH2O activity and lesser silica activity, in some portions of dolostone, brucite has formed in excess of lizardite. This is the first report of brucite mineralisation from this asbestos belt. Major and trace element data indicate a greater contribution from the mafic sill for the formation of black serpentine and a greater role of dolostone in the formation of yellow and green serpentine. A simple mixing model of the 143Nd/144Nd values also supports the contribution of the mafic sill and carbonate in the proportion of 60:40 in the formation of black serpentine. Variation in the concentration of transition metals Fe, V, Cr, Co and Ni is possibly responsible for the development of serpentine having different colours. Serpentinised dolostone commonly shows depletion in δ13C and δ18O values ranging from –1.43 to –0.76‰ and –18.01 to –17.06‰, respectively, compared to those of unaltered dolostone (δ13C: 0.35–0.97‰ and δ18O: –7.11 to –8.75‰). The depletion in δ13C and δ18O values in the serpentinised dolostone is inferred to be caused by decarbonation and interaction with the mafic magma. Serpentinisation of dolostone was accompanied by extensive fracturing and development of stylolites, and followed by hydrothermal fluid flow when some of the early formed serpentines were dissolved in the hydrothermal fluid and re-precipitated as chrysotile filling fractures and stylolites.Research highlightsDolostone in the uppermost part of Vempalle Formation was serpentinised upon emplacement of mafic sill.Chrysotile mineralisation occurred after the serpentinisation of dolostone by dissolution and re-precipitation of previously formed lizardite variety of serpentine.Incidence of brucite mineralisation in serpentinised dolostone of Pulivendla asbestos belt is identified and reported for the first time.

The mafic sills intruding into the dolostone in the uppermost part of the Vempalle Formation, Cuddapah Supergroup, have caused extensive metasomatism in the dolostone, resulting in serpentinisation and hydrothermal chrysotile mineralisation in the Pulivendla asbestos belt. Three different coloured varieties of serpentine, namely black, green, and yellow serpentine, have developed successively away from the mafic sill-dolostone contact. These serpentines belong to the lizardite variety and occur in the form of massive bands, irregular replacement patches, and stylolite fills in dolostone. Due to high X H 2 O activity and lesser silica activity, in some portions of dolostone, brucite has formed in excess of lizardite. This is the first report of brucite mineralisation from this asbestos belt. Major and trace element data indicate a greater contribution from the mafic sill for the formation of black serpentine and a greater role of dolostone in the formation of yellow and green serpentine. A simple mixing model of the 143 Nd/ 144 Nd values also supports the contribution of the mafic sill and carbonate in the proportion of 60:40 in the formation of black serpentine. Variation in the concentration of transition metals Fe, V, Cr, Co and Ni is possibly responsible for the development of serpentine having different colours. Serpentinised dolostone commonly shows depletion in δ 13 C and δ 18 O values ranging from –1.43 to –0.76‰ and –18.01 to –17.06‰, respectively, compared to those of unaltered dolostone ( δ 13 C: 0.35–0.97‰ and δ 18 O: –7.11 to –8.75‰). The depletion in δ 13 C and δ 18 O values in the serpentinised dolostone is inferred to be caused by decarbonation and interaction with the mafic magma. Serpentinisation of dolostone was accompanied by extensive fracturing and development of stylolites, and followed by hydrothermal fluid flow when some of the early formed serpentines were dissolved in the hydrothermal fluid and re-precipitated as chrysotile filling fractures and stylolites. Research highlights Dolostone in the uppermost part of Vempalle Formation was serpentinised upon emplacement of mafic sill. Chrysotile mineralisation occurred after the serpentinisation of dolostone by dissolution and re-precipitation of previously formed lizardite variety of serpentine. Incidence of brucite mineralisation in serpentinised dolostone of Pulivendla asbestos belt is identified and reported for the first time.

Citizen-science driven exercises (e.g. bird surveys) and online platforms (e.g. eBird) provide voluminous data on bird occurrence. However, the semi-structured nature of their data collection makes it difficult to compare bird distribution across space and time. Bird atlases are based on standardized surveys and describe the distribution of bird species over a predefined region and have fewer biases, and thus are better suited for use in research. The recently concluded Kerala Bird Atlas (henceforth KBA) is Asia’s largest bird atlas in terms of geographical extent, sampling effort and species coverage. The entire state of Kerala was systematically surveyed twice a year during 2015–20 and over 0.3 million records of 380 species from 25,000 checklists were aggregated. The dataset was filtered and various metrics were estimated. A total of 915 cells were laid out for systematic surveys, of which 888 were surveyed in either or both the seasons – dry season (January–March) and wet season (July–September); 27 cells could not be surveyed in either of the seasons due to logistical constraints. However, this variation in sampling effort had a minimal effect on survey completeness. The slope of the species accumulation curve suggested nearcomplete species sampling in over 70% of the cells. After eliminating nocturnal and pelagic species, data from 361 species were analysed. Species count was higher in the dry season than in the wet season. Species richness (count) and evenness were higher in the northern and central districts than in the southern districts. High elevation regions of the southern Western Ghats were the largest contiguous areas lacking sufficient sampling. We found that most of the endemics were concentrated in the Western Ghats, but threatened species were as likely to occur along the coasts as in the Ghats. The KBA dataset is a valuable resource for testing various ecological hypotheses and suggesting science-backed conservation measures. KBA model could be replicated for similar atlases in other states or biogeographic regions of India.

Understanding the beneficial plant–microbe interactions is becoming extremely critical for deploying microbes imparting plant fitness and achieving sustainability in agriculture. Diazotrophic bacteria have the unique ability to survive without external sources of nitrogen and simultaneously promote host plant growth, but the mechanisms of endophytic interaction in cereals and legumes have not been studied extensively. We have studied the early interaction of two diazotrophic bacteria, Gluconacetobacter diazotrophicus (GAB) and Bradyrhizobium japonicum (BRH), in 15-day-old seedlings of rice and soybean up to 120 h after inoculation (hai) under low-nitrogen medium. Root colonization of GAB in rice was higher than that of BRH, and BRH colonization was higher in soybean roots as observed from the scanning electron microscopy at 120 hai. Peroxidase enzyme was significantly higher at 24 hai but thereafter was reduced sharply in soybean and gradually in rice. The roots of rice and soybean inoculated with GAB and BRH harvested from five time points were pooled, and transcriptome analysis was executed along with control. Two pathways, “Plant pathogen interaction” and “MAPK signaling,” were specific to Rice- Gluconacetobacter (RG), whereas the pathways related to nitrogen metabolism and plant hormone signaling were specific to Rice- Bradyrhizobium (RB) in rice. Comparative transcriptome analysis of the root tissues revealed that several plant–diazotroph-specific differentially expressed genes (DEGs) and metabolic pathways of plant–diazotroph-specific transcripts, viz. , chitinase, brassinosteroid, auxin, Myeloblastosis (MYB), nodulin, and nitrate transporter (NRT), were common in all plant–diazotroph combinations; three transcripts, viz. , nitrate transport accessory protein (NAR), thaumatin, and thionin, were exclusive in rice and another three transcripts, viz. , NAC (NAM: no apical meristem, ATAF: Arabidopsis thaliana activating factor, and CUC: cup-shaped cotyledon), ABA (abscisic acid), and ammonium transporter, were exclusive in soybean. Differential expression of these transcripts and reduction in pathogenesis-related (PR) protein expression show the early interaction. Based on the interaction, it can be inferred that the compatibility of rice and soybean is more with GAB and BRH, respectively. We propose that rice is unable to identify the diazotroph as a beneficial microorganism or a pathogen from an early response. So, it expressed the hypersensitivity-related transcripts along with PR proteins. The molecular mechanism of diazotrophic associations of GAB and BRH with rice vis-à-vis soybean will shed light on the basic understanding of host responses to beneficial microorganisms.

Human bocaviruses (HBoVs) can cause respiratory illness in young children. Although the first HBoV infection in India was reported in 2010, very little information is available about its prevalence, clinical features, or geographic distribution in this country. This study was conducted using 136 respiratory samples from paediatric patients in a tertiary care hospital in Kerala, 21 of which tested positive for HBoV1 and were further characterized through VP1/VP2 gene sequencing. We found that different strains of HBoV1 are co-circulating in the region and that HBoV1 can be detected in children with severe acute respiratory infections, either alone or coinfections with other pathogens, without any significant differences in their clinical characteristics.