Annual cycle of stored spermatozoa within the ovaries of Helicolenus dactylopterus dactylopterus (Teleostei, Scorpaenidae)

The aim of this work was to analyse the ultrastructure of storage crypts and stored spermatozoa, and to describe changes during the annual reproductive cycle of the bluemouth Helicolenus dactylopterus dactylopterus , which has internal fertilization and a zygoparous mode of reproduction. Spermatozoa had elongated heads and long midpieces, two characteristics which are thought to be fairly advanced and correlated with internal fertilization, as is the case of the bluemouth. A remarkable spermatozoon feature was the retention of a significant quantity of cytoplasm around the head, a condition that appeared to be related to nourishment during the long storage period, up to 10 months in the intraovarian crystal structures of the female. Male sex cells' protection against the female immune system was ensured by junctional complexes between the crypt cells composed of tight junctions and desmosomes.     

Pheophytin-mediated energy storage of photosystem II particles detected by photoacoustic spectroscopy

The photoacoustic (PA) characteristics (energy storage and heat dissipation) of photosystem II (PSII) core-enriched particles from barley were studied (i) in conditions where there was electron flow, i.e., in the presence of a combination of the electron acceptor K₃ Fe (CN)₆, referred to as FeCN, and the electron donor diphenylcarbazide (DPC), and (ii) in conditions where electron flow was suppressed, i.e., in the absence of FeCN and DPC. The experimental data show that a decrease of heat dissipation with a minimum at 540 nm can be interpreted as energy storage resulting from the presence of pheophytin (Pheo) in the PSII particles. On account of the capability of the PA method to measure the energy absorbed by the chromophores which is converted to heat, it is suggested that the PA detection of Pheo present in the PSII complex will permit to clarify the function of processes involving non-radiative relaxation of excited states in P680-Pheo-Q_A interactions.Abbreviations -Car -Carotene - Chl Chlorophyll - DPC Diphenylcarbazide - EPR Electron Paramagnetic Resonance - FeCN potassium ferricyanide - HEPES N-2-hydroxyethylenepiperazine-N-2-ethanesulfonate - P680 reaction center of PSII - PA Photoacoustic - Pheo pheophytin - PSI photosystem I - PSII photosystem II - Q_A primary electron acceptor of PSII     

Release of dormancy during after-ripening of Agrostemma githago seeds

Freshly harvested seeds of Agrostemma githago L. do not germinate when they are imbibed at 20°C. The block is located in the embryo and is relased by dry storage at 20°C (after-ripening). Freshly harvested seeds complete only a small part of the processes that occur in after-ripened seeds during the lag phase prior to germination (radicle protrusion). After-ripening removed the block on lag phase processes much faster than the block on germination. This was shown both by direct determinations of the completion of lag phase processes and by measurements of the rate of axial protein synthesis, which approximately doubles when seeds are progressing through the lag phase. It is concluded that the percentage germination does not adequately reflect the extent to which the dormancy mechanism has been overcome.     

Diurnal water storage in the stems of Picea sitchensis (Bong.) Carr.

Abstract. Two models of the relationship between diurnal variation in shoot water potential and transpiration in 14-year-old Picea sitchensis (Bong.) Carr. were compared. The first model was a physiologically based resistance-capacitance (R-C) analogue with its associated differential equations. The second was a non-physiological discrete-difference (D-D) or stochastic transfer function model. The RC model included only the effect of water storage in the phloem and bark while the D-D model implicity included all storage mechanisms. The R-C and D-D models explained similar fractions (62% and 68% respectively) of the variation in shoot water potential due to diurnal changes in transpiration rate. However, the D-D model had fewer parameters than the R-C model. The results from the D-D model showed that the resistance to flow from soil to shoots along the trunk, (RT), was 5 × 10³ MPa kg^-1s and the capacitance of the phloem and bark treated as a single store, (C_s), was 1.6 kg MPa^-1. It is suggested that the resistance to flow into storage (R_s) is much greater than R_T and can be disregarded. A non-linear version of the D-D model suggested [hat resistance to flow in the trunk increases with increasing transpiration rate.     

cDNA cloning of an mRNA encoding a sulfur-rich 10 kDa prolamin polypeptide in rice seeds

Using a rice maturing seed pUC9 expression library, we isolated a cDNA clone corresponding to 10 kDa sulfurrich prolamin by immunoscreening. A longer cDNA clone was obtained from a gtll library by plaque hybridization using this ³²P-labeled cDNA as a probe. A polypeptide sequence composed of 134 amino acids was deduced from the nucleotide sequence. A 24 amino acid signal peptide was assigned by computer calculation for the membrane spanning region and Edman sequencing of the purified mature polypeptide. Remarkably, 20% of methionine and 10% of cysteine were found in the mature polypeptide as well as high contents of glutamine, and hydrophobic amino acids. Part of the amino acid sequence was homologous with a conserved cysteine-rich region found in other plant prolamins. Two repeats of amino acid sequence were found in the polypeptide.     

Deficient glycosylation of arylsulfatase A in pseudo arylsulfatase-A deficiency

Summary Deficient arylsulfatase-A activity is diagnostic of a neurodegenerative human lysosomal storage disease, metachromatic leukodystrophy. Paradoxically, similar enzyme deficiency also occurs in normal individuals, who are known as being pseudo arylsulfatase-A deficient. We showed previously that this phenotype is associated with a structural gene mutation that produces an exceptionally labile enzyme. We now report on the nature and consequence of this mutation. When the mutant arylsulfatase-A is deglycosylated by endoglycosidase H, only one smaller molecular species was generated, instead of the two from the normal enzyme. This is consistent with the loss of one of the two N-linked oligosaccharide side chains known to be present on the wild-type enzyme. Quantitative analysis of mannose and leucine incorporation showed that the mutant enzyme incorporated two- to tenfold less mannose than the normal enzyme on a molar basis. This deficient glycosylation was specific to arylsulfatase-A. Another lysosomal enzyme not affected in this mutation, beta-hexosaminidase, was glycosylated normally in the mutant cells. The remaining single oligosaccharide side chain released from the mutant arylsulfatase-A by pronase digestion was normally processed to complex and high-mannose forms. However, the high-mannose side chains contained 30% fewer phosphorylated residues than those of the normal enzyme. Nevertheless, this reduced level of phosphorylation did not prevent targeting of the mutant enzyme to the lysosomes, a process normally mediated through phosphorylated mannose residues. In conclusion, pseudo arylsulfatase-A deficiency is a unique human mutation associated with reduced glycosylation and phosphorylation of a lysosomal enzyme with the loss of one of the two carbohydrate side chains. The mutation results in greatly reduced enzyme stability, thus indicating a role for oligosaccharides in maintaining enzyme stability within the degradative environment of the lysosomes. However, the residual catalytic activity or subcellular targeting of the mutant enzyme was not affected. These properties probably account for the benign clinical presentation of pseudo arylsulfatase-A deficiency.Abbreviations PD Pseudo arylsulfatase-A Deficiency - ARA Arylsulfatase-A     

银合欢基因文库的构建和种子贮藏蛋白基因的分离

本文以λEMBL_3为载体,构建了银合欢(Leucaena leucocephala)的基因文库,所得重组子为3.5×10~6pfu。以大豆种子贮藏蛋白α′亚基基因为探针,从基因文库中分离得到了4个阳性克隆,并初步绘制了其中3个重组子的物理图谱。结果表明在这3个重组子的基因内部有一致的酶切位点。亚克隆的部分核苷酸序列与 GenBank 中的基因序列比较,表明与大豆种子贮藏蛋白α′亚基基因高度同源。     

Storage of pollen grains of Crotalaria retusa in oils

Summary Attempts were made to store pollen grains of Crotalaria retusa L. in a mineral oil (paraffin oil) and two vegetable oils (soybean oil and olive oil). Under laboratory conditions pollen grains not stored in oil lost in vitro germinability within 15–30 days, while those stored in oils maintained some degree of germinability even after 60 days. Pollen samples stored in oils at –20° C did not show any decline in germinability or pollen tube vigour even after 6 months of storage. The results amply demonstrate the feasibility of using oils for short- and long-term pollen storage.