Arja Nurmi

Temperature-dependent changes in Photosystem II heterogeneity of attached leaves under high light

Attached leaves of pumpkin (Cucurbita pepo L. cv. Jattiläismeloni) were exposed to high light intensity at room temperature (ca 23°C) and at 1°C. Fluorescence parameters and electron transport activities measured from isolated thylakoids indicated faster photoinhibition of PSII at low temperature. Separation of the α and β components of the complementary area above the fluorescence induction curve of dichlorophenyl-dimethylurea-poisoned thylakoids revealed that at low temperature only the α-centers declined during exposure to high light intensity while the content of functional β-centers remained constant. Freeze-fracture electron microscopy showed no decrease in the density of particles on the appressed exoplasmic fracture face, indicating that the photoinhibited α-centers remained in the appressed membranes at 1°C. Because of the function of the repair and protective mechanisms of PSII, strong light induced less photoinhibition at room temperature, but more complicated changes occurred in the α/β-heterogeneity of PSII. During the first 30 min at high light intensity the decrease in α-centers was almost as large as at 1°C, but in contrast to the situation at low temperature the decrease in α-centers was compensated for by a significant increase in PSIIβ-centers. Changes in the density and size of freeze-fracture particles suggest that this increase in β-centers was due to migration of phosphorylated light-harvesting complex from appressed to non-appressed thylakoid membranes while the PSII core remained in the appressed membranes. This situation, however, was only transient and was followed by a rapid decrease in the functionalβ-centers.

9. The social and textual embedding of multilingual practices in Late Modern English: A corpus-based analysis

The social and textual embedding of multilingual practices in Late Modern English : A corpus-based analysis

Minority voices in literary fiction: a case study of translating multilingual practices

Abstract Translating multilingual texts is still a new field of inquiry. Transplanting a text where the function of embraced multilingual practices is strongly related to local ethnic identities can provide challenges for translators and readers alike. This study discusses the translation strategies adopted by second-year translation students on an assignment to translate part of Patricia Grace’s short story “The Dream” into Finnish. The strategies for dealing with the Maori passages in the story varied, both in terms of how many of the Maori passages were preserved and how much intratextual translation was included in the text. The strategies were investigated both in the translations themselves and in the accompanying translation comments the students produced. The degree to which the translators showed an in-depth understanding of the nuances relevant to the representation of an ethnic minority of another culture varied. There was more sensitivity to a Finnish reader’s insufficient familiarity with the Maori language and culture than to the meaning of the representations of Maori language and culture in the original text.

May: The social history of an auxiliary

This paper explores the social history of the modal auxiliary may between 1400-1800. The material used comes from the Corpora of Early English Correspondence. The development of may on the lexical level is tracked with regard to the social variables of gender, rank, social mobility, education and register variation. The social embedding of the rising epistemic meaning is then described with the help of a socially stratified sample of instances. The results show that the use of may is connected to the expression and negotiation of relative power and intimacy between correspondents. Furthermore, the rise of epistemic may originated with educated men, and spread gradually to other language users.

The role of gender in the use of MUST in Early Modern English

This study uses the 2.7 million word Corpus of Early English Correspondence to trace the development of the modal auxiliary MUST and its two main meanings, ’personal obligation’ and ’logical necessity’ through the span of the corpus, from the early 15th century to the late 17th. The approach is sociolinguistic, with particular reference to gender differences in the use of the auxiliary. The main finding is that MUST increased steadily in frequency during the Early Modern English period. This increase is found both in the language of men and women, with men leading in the use of MUST in the 15th century and women reaching and overtaking their level of usage by the 17th century. The use of MUST also increases in both meanings, but the ’logical necessity’ meaning is clearly less frequent than the ’personal obligation’ sense. The rise of ’logical necessity’ seems to stem from educated men, from whom its use spreads to other men and to educated women.

Alteration in Thylakoid Composition and Structure of Brassica rapa ssp. Oleifera During Ageing in High and Low Light

The organization and function of thylakoid proteins are greatly affected by environmental conditions. Under changing environmental conditions, many protein complexes are involved in shaping the thylakoid architecture, the final structure depending on the balance between different thylakoid complexes. In this study the organization of membrane proteins was examined in plant material ageing under different environmental conditions. Freeze-fracture, electron microscopic and electrophoretic studies were made of protein complexes in the chloroplast thylakoid of Brassica rapa ssp. oleifera grown in high and low light.

Effects of Light and Temperature on PSII Heterogeneity

It is generally accepted that nearly 30% of PSII (PSIIβ) is located in non-appressed thylakoid regions where it is associated with smaller light-harvesting chl a/b antenna (LHCII) than the bulk of PSII (PSIIα) in grana partitions (1). In addition to this antenna size heterogeneity there are PSII populations differing from each others in the properties of the reducing side. PSII-QB-reducing centers are connected to the plastoquinone pool functioning in vivo in electron transfer from water to NADP. PSII-QB-nonreducing centers are inefficient in this respect due to impaired electron transfer from QA to QB. It has been suggested that in mature spinach leaves the PSIIβ and PSII-QB-nonreducing constitute one and the same pool of PSII centers but under light of present knowledge, however, this generalization is not always valid (1).

Effect of Daylength on Thylakoid Composition and Ultrastructure in Brassica Rapa Ssp. Oleifera

Proteins and lipids have been suggested to play an important part in the thylakoid organization in biological membranes (1) and some specific lipid-protein interactions could be necessary for the functioning of different intrinsic membrane protein (2). High temperatures have been shown to induce alterations in the chloroplast membrane structure (3). Heating leads to structural reorganization of membranes and phase-separated aggregates of non-bilayer forming lipids are observed (4). This study reports the presence of micelles in Brassica raga ssg. oleifera grown in long daylengths. At the time when they were observed, also changes in the light-harvesting component occured.