Microplastics in agroecosystems: A review of effects on soil biota and key soil functions

Contamination of soils in agroecosystems with microplastics (MPs) is of increasing concern. The contamination of the environment/farmland soils with MPs (1 µm to 5 mm sized particles) and nanoplastics (NPs; <1 µm sized particles) is causing numerous effects on ecological soil functions and human health. MPs enter the soil via several sources, either from intentional plastic use (e.g., plastic mulch, plastic greenhouses, plastic-coated products) or indirectly from the input of sewage sludge, compost, or irrigation water that is contaminated with plastic. Once in the soil, plastic debris can have various impacts such as changes in soil functions and physicochemical properties and it affects soil organisms due to its toxic behavior. This review paper describes the different effects of plastic waste to understand the consequences for agricultural productivity. Furthermore, we identify knowledge gaps and highlight the required approaches, indicating future research directions on sources, transport, and fate of MPs in soils to improve our understanding of various unspecified abiotic and biotic impacts of MP pollution in agroecosystems.     

Requirement for Tec kinases Rlk and Itk in T cell receptor signaling and immunity

T cell receptor (TCR) signaling requires activation of Zap-70 and Src family tyrosine kinases, but requirements for other tyrosine kinases are less clear. Combined deletion in mice of two Tec kinases, Rlk and Itk, caused marked defects in TCR responses including proliferation, cytokine production, and apoptosis in vitro and adaptive immune responses to Toxoplasma gondii in vivo. Molecular events immediately downstream from the TCR were intact in rlk-/-itk-/- cells, but intermediate events including inositol trisphosphate production, calcium mobilization, and mitogen-activated protein kinase activation were impaired, establishing Tec kinases as critical regulators of TCR signaling required for phospholipase C-gamma activation.     

Digestive Cecum and Tissue Redistribution in Gills of Telescopium telescopium as Indicators of Ni Bioavailabilities and Contamination in Tropical Intertidal Areas

The relationships between the Ni concentrations of the mudflat snails Telescopium telescopium and the surface sediments have not been reported yet from tropical intertidal areas. In this study, telescope snails and surface sediments were collected from 18 geographical sampling sites in intertidal areas of Peninsular Malaysia. The concentrations of Ni were measured in seven different soft tissues of the snails namely foot, cephalic tentacles, mantle, muscle, gill, digestive cecum, and remaining soft tissues. It was found that different concentrations of Ni were found in the different soft tissues, indicating different mechanisms of sequestration and regulation of Ni in these different tissues. By comparing the Ni concentrations in the similar tissues, spatial variations of Ni were found in the different sampling sites although there was no consistent pattern of Ni in these sites. The highest Ni variation based on the ratio of maximum to minimum values indicated that cephalic tentacle and foot were the main organs having high Ni variation. The use of correlation analysis and multiple linear stepwise regression analysis revealed that digestive cecum of T. telescopium could be used to reflect the Ni contamination of the sampling site. Also, the digestive cecum and gill were found to be the main bioaccumulation and storage sites for Ni. From the Ni accumulation patterns in all the populations investigated, tissue redistributions of Ni in gill was identified and could be proposed as an indicator of high Ni bioavailability and contamination in the sampling site. To our knowledge, this is the first and most comprehensive study on Ni accumulation in the different soft tissues of T. telescopium from tropical intertidal areas, in relation to the sediment data.     

甜菜幼苗的分区及其肥大直根的定位研究

本文按照子叶节区理论(Cotyledon node zone theory)研究结果表明, 甜菜幼苗的子叶节区类型为顶枝伸长型(Telome elongation type)。 甜菜肥大直根采用幼苗分区定位法明确其根头部由上胚轴苗区发育而成; 根颈部与根体是由长的顶枝伸长型的子叶节区发育而来; 至于下面短的根尾, 是下胚轴发育的产物; 甜菜真正的根并不肥大     

Performance and cost‐effectiveness of sexually produced Acropora granulosa juveniles compared with asexually generated coral fragments in restoring degraded reef areas

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Recruitment patterns and early growth of acroporid corals in Manado, Indonesia

A coral settlement device was used to examine recruitment patterns of Acropora at two stations (st.; A and B) in Bunaken Island, Manado. The recruitment timing of Acropora was not determined because of mixing with Isopora. A marine block (MB) was used to observe the growth of settled acroporid corals at st. A. Within a year of settlement (February–May of the following year), the corals which had settled on the MB had grown to a size of 13.4 ± 5.86 mm. They were dominated by Isopora, with a small proportion of Acropora. A supplementary experiment again using the MB was conducted at three other sites (st. C, D, E) where Isopora was not abundant. The size of the corals which settled on the MB was nearly the same as that of the corals at st. A. Juvenile Acropora corals (≤3 cm, encrusting form) were measured on the Manado coast (st. F) between February and May. At this site, Acropora corals were dominant and no Isopora corals were observed; the size of Acropora was 18.5 ± 5.01 mm. Acroporid corals in February and March at st. A appeared smaller than those at st. F and grew to nearly the same size in early April.     

Ovarian activity in beef and dairy cows with prolonged postpartum period and heifers that fail to conceive

The primary objectives of this study were to investigate incidence of abnormal ovarian cyclicity (AOC) and its type in dairy and beef cows with prolonged postpartum period (>90 days) and in heifers that fail to conceive. A total of 53 animals were included in the study: 17 Friesian crosses, 16 Braford crosses, eight Brangus crosses, and 12 local Kedah-Kelantan (KKX) crosses. These animals were initially checked for absence of pregnancy via palpation per rectum. Blood samples for progesterone analysis were obtained twice a week for 2 to 3 months following their spontaneous oestrous cycle, and all animals were rechecked for pregnancy at the end of the study. Progesterone analysis indicated that 33.9% of the total animals were having AOC: 18.9% with cessation of ovarian cyclicity, 9.4% with prolonged luteal phases (PLP), and 5.7% short luteal phases. The highest incidence was observed in Brangus crosses (62.5%), followed by Braford crosses (43.8%), and Friesian crosses (35.3%). In contrast, no AOC was observed in the local KKX breeds, and all of them were found to be pregnant at the end of the study. A significant difference (p < 0.05) in the incidence of AOC and its type was observed between Kedah-Kelantan crosses and the other breeds. Although not significant (p > 0.05), Friesian crosses showed a higher percentage incidence of AOC than beef cows (40% vs 36.4%), with major types being PLP (26.7%) in dairy and cessation of ovarian cycle (27.3%) in beef cows. Compared with beef heifers, beef cows showed a higher percentage of AOC (36.4% vs 28.6%) where again, cessation of cyclicity was the predominant abnormality. In conclusion, AOC reflected by abnormal endocrine pattern is a possible cause of reduction in fertility for dairy and beef cows beyond 90 days postpartum and heifers that fail to conceive.     

The physiology of Cymbidium plantlets cultured in vitro under conditions of high carbon dioxide and low photosynthetic photon flux density

Summary

Cymbidium plantlets were grown in vitro under conditions of high CO₂ and low photosynthetic photon flux density using the Miracle Packt culture system. Shoots and roots of plantlets showed differential growth characteristics. Shoot growth was not different in plantlets cultured under CO₂-enriched (CDE) and non-enriched (NCDE) conditions. Root growth was promoted in plantlets cultured under CDE in the presence or absence of 2% sucrose (S) with rockwool (R) as the supporting material. Growth was poor in plantlets cultured in 1% agar. Root growth was best in plantlets cultured under CDE R+S. Sucrose is still an important component for root growth under CDE conditions even though CO₂ can be used as an alternative carbon source. Photosynthetic measurements (CO₂ uptake and total Rubisco activity) showed the presence of active and operational photosynthetic machinery in plantlets cultured under CDE and NCDE conditions. The apparent lack of photoautotrophy (as evident from the lack of starch grains in chloroplasts) in plantlets cultured under NCDE conditions is not the result of a lesser potential for photoautotrophy; rather it is a consequence of sub-optimal CO₂ concentrations within the culture vessels.     

Modelling sulphur dioxide levels in the Sarnia area

For environmental planning and policy-making purposes, this study was undertaken to apply the Ontario Ministry of the Environment Air Quality Model for SO₂ to an urban-industrial region, namely, the Sarnia and St. Clair River area. Predicted and measured SO₂ levels showed good agreement. A comparison of daily model predictions with 118 observations from 11 monitoring stations for 12 days in 1973 gave an overall correlation coefficient of 0.88.