The ultrastructure of the plasma membrane at the division furrow of grasshopper germ cells

Summary Evidence is provided from cinematography and electron microscopy that chemical processes are responsible for both plasma membrane synthesis and cell separation in dividing germ cells of the grasshopper. Polyribosome-like material is deposited as a ring equatorially, which determines the presumptive division plane. The material deposited at the division plane, in synergism with cytoplasmic material and existing plasma membrane, synthesizes the new plasma membrane. The polyribosome-like material polymerizes into helices, and as the coils of the helices tighten less surface becomes available for membrane synthesis. The decreasing rate of plasma membrane synthesis is the mechanism for cell separation. Thus, plasma membrane synthesis and cell separation occur simultaneously, directed by the same dynamic processes.Work supported under the auspices of the U. S. Atomic Energy Commission.     

The influence of light,darkness, and lack of CO2 on phloem translocation in detached maize leaves

Summary Longitudinal strips from leaf blades of Zea mays L., with veins continuous along their whole length, proved to be a very uniform and convenient material for translocation experiments. Under normal photosynthetic conditions a very strong basipetal assimilate movement was shown. In the dark this movement persisted as long as starch reserves were available. Parts of the strips exposed to darkness or to CO₂-free air, i.e. nonphotosynthetic conditions, became strong sinks which attracted assimilates, darkness having the strongest effect. Microradioautographs showed that transport of assimilates took place in the sieve tubes of the phloem.     

Actions of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on human epidermal keratinocytes in culture

Summary In humans, the skin is a particularly sensitive target for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and certain halogenated analogs. Reported lesions include a thickening of the epidermis (acanthosis), hyperkeratosis, and squamous metaplasia of the epithelial lining of the sebaceous glands. In this report we describe ongoing studies on the actions of TCDD on cultured human epidermal cells. This system has been established as an in vitro model for interfollicular epidermal hyperkeratinization. Treatment of newly confluent cultures with TCDD results in enhanced differentiation as judged by histologic examination of the cultures, a decrease in the number of basal proliferating cells, and an increase in the number of envelope competent (differentiating) cells and terminally differentiated cells with highly cross-linked cornified envelopes. Changes in the differentiation program are preceded by a decrease in epidermal growth factor (EGF) binding. The concentration dependence and stereospecificity for these responses suggest the involvement of theAh receptor. We propose that TCDD modulates normal patterns of epidermal differentiation through direct actions on proliferating basal cells, modulating the responsiveness of these cells to growth factors such as EGF. This paper was presented at the Session-In-Depth on In Vitro Applications in Toxicology at the 34th Annual Meeting of the Tissue Culture Association, Orlando, FL, June 12–16, 1983. Rosemarie Osborne was a Chemical Industry Institute of Toxicology Postdoctoral Fellow.     

Inhibition of homologous recombination by hyperthermia shunts early double strand break repair to non-homologous end-joining

In S and G2 phase mammalian cells DNA double strand breaks (DSBs) can potentially be repaired by homologous recombination (HR) or non-homologous end-joining (NHEJ). Results of several studies suggest that these two mechanistically distinct repair pathways can compete for DNA ends. Because HR and NHEJ differ with respect to error susceptibility, generation of chromosome rearrangements, which are potentially carcinogenic products of DSB repair, may depend on the pathway choice. To investigate this hypothesis, the influence of HR and NHEJ inhibition on the frequencies of chromosome aberrations in G2 phase cells was investigated. SW-1573 and RKO cells were treated with mild (41 °C) hyperthermia in order to disable HR and/or NU7441/cisplatin to inactivate NHEJ and frequencies of chromosomal fragments (resulting from unrepaired DSBs) and translocations (products of erroneous DSB rejoining) were studied using premature chromosome condensation (PCC) combined with fluorescence in situ hybridization (FISH).It is shown here that temporary inhibition of HR by hyperthermia results in increased frequency of ionizing-radiation (IR)-induced chromosomal translocations and that this effect is abrogated by NU7441- or cisplatin-mediated inhibition of NHEJ. The results suggest that in the absence of HR, DSB repair is shifted to the error-prone NHEJ pathway resulting in increased frequencies of chromosomal rearrangements. These results might be of consequence for clinical cancer treatment approaches that aim at inhibition of one or more DSB repair pathways.     

'Candidatus Liberibacter europaeus' sp. nov. that is associated with and transmitted by the psyllid Cacopsylla pyri apparently behaves as an endophyte rather than a pathogen

'Candidatus Liberibacter spp.' cause serious plant diseases. 'Candidatus Liberibacter asiaticus', 'Ca. L. americanus' and 'Ca. L. africanus' are the aetiological agents of citrus greening (Huanglongbing) in Asia, America and Africa. 'Candidatus Liberibacter solanacearum' causes diseases in Solanaceae in America and New Zealand. All four species are vectored by psyllid insects of different genera. Here, we show that the pear psyllid pest Cacopsylla pyri (L.) hosts a novel liberibacter species that we named 'Ca. Liberibacter europaeus'. It can bloom to high titres in the psyllid host, with more than 10(9) 16S rRNA gene copies per individual. Fluorescent in situ hybridization experiments showed that 'Ca. L. europaeus' is present in the host midgut lumen, salivary glands and Malpighian tubules. 'Candidatus L. europaeus' has a relatively high prevalence (> 51%) in C. pyri from different areas in the Piedmont and Valle d'Aosta regions in Italy and can be transmitted to pear plants in experimental transmission trials. However, even though high titres of the bacterium (more than 10(8) 16S rRNA gene copies g(-1) of pear plant tissue) could be detected, in the pear tissues no specific disease symptoms could be observed in the infected plants over a 6-month period. Despite liberibacters representing potential quarantine organisms, 'Ca. L. europaeus', first described in Italy and Europe, apparently behaves as an endophyte rather than a pathogen.     

Family caregivers' experiences of involuntary psychiatric hospital admissions of their relatives--a qualitative study

Background

Family caregivers of people with mental disorders are frequently involved in involuntary hospital admissions of their relatives.

Objective

To explore family caregivers'' experience of involuntary admission of their relative.

Method

30 in-depth interviews were conducted with family caregivers of 29 patients who had been involuntarily admitted to 12 hospitals across England. Interviews were analysed using thematic analysis.

Results

Four major themes of experiences were identified: relief and conflicting emotions in response to the relative''s admission; frustration with a delay in getting help; being given the burden of care by services; and difficulties with confidentiality.Relief was a predominant emotion as a response to the relative''s admission and it was accompanied by feelings of guilt and worry. Family caregivers frequently experienced difficulties in obtaining help from services prior to involuntary admission and some thought that services responded to crises rather than prevented them. Family caregivers experienced increased burden when services shifted the responsibility of caring for their mentally unwell relatives to them. Confidentiality was a delicate issue with family caregivers wanting more information and a say in decisions when they were responsible for aftercare, and being concerned about confidentiality of information they provided to services.

Conclusion

Compulsory admission of a close relative can be a complex and stressful experience for family caregivers. In order for caregivers to be effective partners in care, a balance needs to be struck between valuing their involvement in providing care for a patient and not overburdening them.     

Evolutionary Psychology��s Place in Evolutionary Studies: a Tale of Promise and Challenge

The Evolutionary Studies (EvoS) Consortium and the academic programs born from its creation have been wildly successful in their initial ventures. These achievements are marked by feedback from across the EvoS campuses, the resultant scholarly work produced by participating students, and faculty collaborations spurred by exposure to the organization. The success of EvoS is probably best marked by the recent National Science Foundation grant (CCLI Award #0817337), awarded jointly to SUNY New Paltz and Binghamton University, with the purpose of expanding EvoS beyond the bounds of these two institutions. A particularly noteworthy element of many EvoS programs is the role of Evolutionary Psychology (EP), a perspective in the behavioral sciences that addresses questions of human behavior from the perspective of evolution. In light of several forms of data, including analyses of a variety of disciplines drawn on from evolutionary psychologists in their work, we argue that evolutionary psychologists may well be the most naturally interdisciplinary scholars within the behavioral sciences, making them highly appropriate for inclusion in EvoS. But our research shows not only promise regarding the relationship between EP and EvoS—challenges are raised as well. We present additional data showing that EP is currently represented disproportionately within the EvoS world—a fact that clearly shows that there are currently limitations to the potential impact of EvoS in modern academia. Scholars from other disciplines, particularly within the humanities and social sciences, seem to be missing the evolution revolution. Implications regarding how EvoS can broaden its scope to be even more powerful in its integrative scope are discussed.