Ovariectomy predisposes female rats to fine particulate matter exposure’s effects by altering metabolic,oxidative, pro-inflammatory,and heat-shock protein levels

Environmental Science and Pollution Research - The reduction of estrogen levels, as a result of menopause, is associated with the development of metabolic diseases caused by alterations in...     

Purification and partial characterisation of phenoloxidase from the colonial ascidian Botryllus schlosseri

Phenoloxidase (PO) from the colonial ascidian Botryllus schlosseri was purified using two different chromatographic strategies. A three-step purification was developed in order to maintain enzyme activity, whereas an easier purification procedure was adopted to obtain enough PO for the production of specific polyclonal antibodies. The enzyme showed optimal pH and temperature values of 7.0 to 7.5 and 35 °C, respectively, and a K _m value of 4.62 ± 0.76 mM was estimated using l-DOPA as substrate. A molecular weight of 160 kDa was determined after SDS-PAGE under non-reducing conditions. The addition of the reducing agent β-mercaptoethanol caused the disappearance of the 160 kDa band and the appearance of a new band at 80 kDa, suggesting that active PO is a dimer and the two subunits are linked by disulphide bridges. Received: 14 December 1998 / Accepted: 24 August 1999     

Involvement of quinones and phenoloxidase in the allorejection reaction in a colonial ascidian, Botrylloides simodensis: histochemical and immunohistochemical study

When incompatible colonies of Botrylloides simodensis were brought into contact at their artificially cut surfaces, allorejection occurred and a black line was formed along the contact border. Morula cells (MCs), a type of hemocytes, are the major effector in the allorejection reaction and are known to possess phenoloxidase (PO) that generates quinones. In this rejection reaction, MCs infiltrate the tunic and break down, discharging their vacuolar contents. Ascorbic acid (antioxidant) and benzamidine (protease inhibitor) showed inhibitory effects on MC breakdown, black line formation and new tunic cuticle formation, whereas tropolone (metal chelator) and sodium benzoate (substrate analog) did not. MCs probably store some amount of quinones, as well as PO; oxidants derived from the quinones appear to disintegrate the tissue to form a black line and promote MC breakdown. Histochemical and immunohistochemical studies revealed that MCs contain eosinophilic materials, PO and quinones. Quinones that are stored in MCs and produced by PO probably have a destructive function, forming rejection lesions.