Subchronic toxicity là gì? Các công bố khoa học về Subchronic toxicity

The paper argues that the mutually enforcing processes of enclosure of land and entanglement of labour have been central to the development of state and capitalism in Kuttanad, a protected Ramsar site in the south Indian state of Kerala. The driving force of epochal changes in Kuttanad was the transformations of the commons; different regimes that ruled Kuttanad have actively engaged in the appropriation, distribution and production of commons along with and for the dominant sections in the region. Reclamation and re-reclamation of backwater lands, spanning over one and half centuries, are thus carried out by the distributive state apparatus in collaboration with its constituent class sections. The resultant shifts in land, crop, labour, technology and resources are what define the crisis of commons in the region.

The Edwards Dam, located on the Kennebec River of Maine, in the state’s capitol city, was removed in 1999 to restore fisheries such as alewives, striped bass, American shad, and endangered short-nosed sturgeon. The dam removal was ordered by the Federal Energy Regulatory Commission for the express purpose of restoring fisheries, the first time ever this was done in American history. This article examines the local environmental advocacy for river and fisheries restoration and the process resulting in dam removal and fisheries restoration. It argues that the Edwards Dam removal was critical in proving the environmental benefits of river restoration through removal as well as some economic benefits. This contributed to other U.S. efforts to remove dams to restore fisheries and assisted the expansion of this stage of American environmentalism. The article uses a number of primary sources including local newspapers, environmental group materials, and a number of interviews collected by the author.

Sensilla are small hair-like structures modified for the perception of specific stimuli and thereby helping in finding conspecific mates and suitable oviposition sites apart from controlling feeding behavior. The knowledge of type as well as morphology of sensilla helps in understanding their role in the host selection procedure, mate finding and pheromone detection. The scanning electron micrograph revealed the presence of seven different types of sensilla viz., sensilla trichodea 1(ST1); sensilla trichodea 2(ST2) sensilla trichodea 3 (ST3) sensilla basiconica (SB); sensilla chaetica (SCh); sensilla coeloconica (SCo) and sensilla flagellate (SF) on the antenna of K. chinensis. Sensilla trichodea (ST) are slender and flexible hair-shaped sensilla, while SB is thick walled sensilla with sharp-apex, SCh are long, straight, and stiff hair-like structures, SCo are short peg like sensilla with a thin wall, smooth surface, and wider base; and SF are smooth-walled and slender with flexible socket. They are having a floret-like apex with possible apical pores, and are embedded in non-flexible sockets. The study on type and morphology of antennal sensilla of Keria chinensis, the most important and commercially exploited lac insect species revealed significant variations in numbers across the scape, pedicel and flagellum. The numbers of sensilla present on the scape, pedicel and flagellum of the nymphal instars was recorded to be 2.40 ± 0.25, 2.20 ± 0.16 and 13.90 ± 2.07, respectively after 45 days of brood lac inoculation (DAI). The scape, pedicel and flagellum of male stands higher numbers of sensilla (2.60 ± 0.23, 5.50 ± 0.51 and 66.62 ± 3.96, respectively) including sensilla trichoidea (ST1, ST2, ST3), sensilla basiconica (SB), and sensilla flagellum (SF) on the proximal part as against sensilla cheatica (SCh) and sensilla coeloconica (SCo) on the apical flagellomeres. The size of ST1 present on the antenna was found higher (45.30 ± 0.65 μm − 45.90 ± 0.43 μm on length and 0.88 ± 0.39 μm − 0.97 ± 0.02 μm on width) as against 23.60 ± 0.40 μm − 28.10 ± 0.58 μm on length and 0.70 ± 0.07 μm − 0.97 ± 0.02 μm on width in the case of ST3. The length of SB varied from 22.60 ± 0.30 μm and 25.20 ± 0.41 μm as against its width that varied from 0.22 ± 0.02 μm and 0.31 ± 0.03 μm. SF was lacking on the male insects, which found varied from 146.40 ± 0.26 μm − 147.60 ± 0.52 μm in length and 0.82 ± 0.02 μm − 0.97 ± 0.01 μm in width on nymphal instars. Sensilla basiconica was found to be highest on nymphal instars while ST 3 was found to be highest on male lac insect. However SC was found to be least in numbers on the antennae of K. chinensis. Thus, the chemosensilla present on antenna might play a major role in host plant selection as well as the mate finding by K. chinensis.

Plastic production is increasing rapidly at a global scale and microplastics are widely distributed in aquatic ecosystems and food webs. As filter feeders, bivalves present entry points for microplastics into food webs and numerous descriptive and experimental studies have addressed microplastic size selection by bivalves. However, much less is known about size selection of microplastic fibers by bivalves. This represents a gap in understanding of how microplastics impact bivalves and food webs, particularly given the numerical dominance of microplastic fibers in freshwater and marine ecosystems and in bivalve tissue. To address this gap, we tested two hypotheses: (1) the net accumulation of polyester fibers in zebra mussels (Dreissena polymoropha) is dependent on fiber size and (2) zebra mussel size impacts the amount of plastic fibers accumulated. We conducted two experiments to test these hypotheses. In the first experiment, we exposed zebra mussels to pink polyester fibers (PPF) of four different lengths (0.25–2.0 mm), offered separately. In the second experiment, we exposed mussels with PPF of three different lengths (0.25–1.0 mm) in a mixture. Both hypotheses were supported. In each experiment, PPF of the smallest size (0.25 mm) disproportionately accumulated in the mussels. In addition, PPF accumulation of 0.25 and 0.50 mm PPF increased as zebra mussel shell length increased. Our results have implications for how microplastic fibers in water columns may impact bivalves and their food webs and demonstrate that size distribution should be considered when sampling bivalves for microplastics in ecosystems.