Jumping the gun: smoking constituent BaP causes premature primordial follicle activation and impairs oocyte fusibility through oxidative stress.

Benzo(a)pyrene (BaP) is an ovotoxic constituent of cigarette smoke associated with pre-mature ovarian failure and decreased rates of conception in IVF patients. Although the overall effect of BaP on female fertility has been documented, the exact molecular mechanisms behind its ovotoxicity remain elusive. In this study we examined the effects of BaP exposure on the ovarian transcriptome, and observed the effects of in vivo exposure on oocyte dysfunction. Microarray analysis of BaP cultured neonatal ovaries revealed a complex mechanism of ovotoxicity involving a small cohort of genes associated with follicular growth, cell cycle progression, and cell death. Histomorphological and immunohistochemical analysis supported these results, with BaP exposure causing increased primordial follicle activation and developing follicle atresia in vitro and in vivo. Functional analysis of oocytes obtained from adult Swiss mice treated neonatally revealed significantly increased levels of mitochondrial ROS/lipid peroxidation, and severely reduced sperm-egg binding and fusion in both low (1.5mg/kg/daily) and high (3mg/kg/daily) dose treatments. Our results reveal a complex mechanism of BaP induced ovotoxicity involving developing follicle atresia and accelerated primordial follicle activation, and suggest short term neonatal BaP exposure causes mitochondrial leakage resulting in reduced oolemma fluidity and impaired fertilisation in adulthood. This study highlights BaP as a key compound which may be partially responsible for the documented effects of cigarette smoke on follicular development and sub-fertility.

p97 and close encounters of every kind: a brief review.

The AAA (ATPase associated with various cellular activities) ATPase, p97, is a hexameric protein of chaperone-like function, which has been reported to interact with a number of proteins of seemingly unrelated functions. For the first time, we report a classification of these proteins and aim to elucidate any common structural or functional features they may share. The interactors are grouped into those containing ubiquitin regulatory X domains, which presumably bind to p97 in the same way as the p47 adaptor, and into non-ubiquitin regulatory X domain proteins of different functional subgroups that may employ a different mode of interaction (assuming they also bind directly to p97 and are not experimental artifacts). Future studies will show whether interacting proteins direct p97 to different cellular pathways or a common one and structural elucidation of these interactions will be crucial in understanding these underlying functions.

Characterization of the soluble form of the low density lipoprotein receptor-related protein (LRP).

We report characterization of the soluble form of the low density lipoprotein receptor-related protein (sLRP) which circulates in human plasma. Amino acid sequence analysis confirmed that sLRP isolated from human plasma contains the alpha-chain of LRP1. In addition, Western blot analysis identified a truncated beta-chain noncovalently associated with the purified alpha-chain. The molecular size (M(r) 55K) of the peptide portion of the truncated beta-chain indicates that the subunit comprises the extracellular portion of the beta-chain and terminates in a membrane-proximal region. We investigated the mechanism by which sLRP may be generated using the trophoblast cell line, BeWo, which releases sLRP in culture. Cell surface labeling experiments indicate that LRP is released from BeWo cells following expression at the cell surface. Incubation of BeWo cells in the presence of a metalloproteinase inhibitor, INH-3855-PI, results in a dose-dependent inhibition of LRP shedding. The metalloproteinase responsible for the shedding of LRP by BeWo cells is not up-regulated by phorbol ester and is not dependent on serine proteases, such as plasmin, for activity. The BeWo cell line is derived from a human gestational choriocarcinoma and preliminary studies suggest that LRP may be shed within the placenta during gestation. Increased levels of sLRP were detected in cord blood. In term placenta, LRP is expressed in the syncytium, which comprises the maternal-fetal interface. Increased levels of sLRP in cord blood may reflect cellular dysfunction and increased metalloproteinase activity at this important interface.

Apolipoprotein E uptake and low-density lipoprotein receptor-related protein expression by the NTera2/D1 cell line: a cell culture model of relevance for late-onset Alzheimer's disease.

Apolipoprotein E has been shown to be a risk factor for late-onset Alzheimer's disease, with the apolipoprotein epsilon 4 allele conferring the risk. Apolipoprotein E is found in neurofibrillary tangles and senile plaques, the pathological characteristics of Alzheimer's disease. To date there is no direct evidence that human neurons can take up exogenous apolipoprotein E, which is necessary if apolipoprotein E is involved in the formation of neurofibrillary tangles. To examine apolipoprotein E uptake we employed the human NTera2/D1 cell line, which can be induced by retinoic acid to differentiate into postmitotic NTera2-N neurons, which have the characteristics and morphology of human central nervous system neurons. We defined the cell line as genotype apolipoprotein epsilon 3/3 and demonstrated that the cells do not synthesize apolipoprotein E but can take up and internalize exogenous recombinant apolipoprotein E3. We also confirmed the expression of the low-density lipoprotein receptor-related protein, a known receptor for apolipoprotein E. The NTera2/D1 cell line therefore provides a useful human cell model for examining the effects of other apolipoprotein E isoforms with a view to defining intraneuronal interactions of apolipoprotein E.

Ground water contamination in the United States.

Ground water contamination is of increasing concern in the United States because about 50 percent of our drinking water comes from well water. The causes of contamination stem from both point sources and nonpoint sources. Since ground water moves slowly, the contaminant may affect only a small portion of an aquifer for a considerable period of time. Deleterious effects on human health have resulted from pathogenic organisms in ground water and from its toxic chemical composition. It is difficult to estimate the extent of contamination on a national basis as the frequency of instances of contamination is very variable. Remedial actions to clean up aquifers are difficult, expensive, and sometimes not feasible. Many of the laws and regulations that control ground water contamination are designed with other main objectives.

Factors affecting oxygen consumption in the woodlouse Porcellio scaber latr.

1. There is a well-defined time sequence in the oxygen consumption of Porcellio scaber. A maximal rate (the 'active rate') is obtained in woodlice subjected to the maximal disturbance of food presentation, handling and light. After initial exploratory activity has ceased, the oxygen consumption declines through a series of 'excited rates' towards the 'standard rate' which is approached after 2-3 hr equilibration in a respirometer. 2. The rate following starvation for 1-3 days is similar to the standard rate. 3. Thermal acclimation has no significant effect on the slope or the level of the rate: temperature curves for the excited or the standard rate of oxygen consumption of Porcellio scaber. 4. The rate: temperature curves for active, excited and standard oxygen consumption of Porcellio scaber have a double sigmoid form with high temperature coefficients at the extremes of the experimental temperature range. 5. The respiration rate of a homogenate of Porcellio scaber in the presence of 9.0 mM succinate is intermediate between the active and standard rate of the intact animal. 6. The maximum scope for activity is highest at 10-15°C and falls towards both higher and lower experimental temperatures. 7. The overall oxygen consumption of intact Porcellio scaber may reflect the summation of 'cellular' and 'organismic' metabolic components which account for approximately equal proportions of the total metabolism at the normal environmental temperature range of 10-15°C. Below this temperature the cellular component is predominant whilst at the upper limits of the experimental temperature range oxidative metabolism is represented solely by the organismic component.