Homologies between members of the germin gene family in hexaploid wheat and similarities between these wheat germins and certain Physarum spherulins

By screening approximately 10(6) plaques in a wheat DNA library with a "full-length" germin cDNA probe, two genomic clones were detected. When digested with EcoRI, one clone yielded a 2.8-kilobase pair fragment (gf-2.8) and the other yielded a 3.8-kilobase pair fragment (gf-3.8). By nucleotide sequencing, each of gf-2.8 and gf-3.8 was found to encode a complete sequence for germin and germin mRNA, and to contain appreciable amounts of 5'- and 3'-flanking sequences. The "cap" site in gf-2.8 was determined by primer extension and the corresponding site in gf-3.8 was deduced by analogy. The mRNA coding sequences in gf-2.8 and gf-3.8 are intronless and 87% homologous with one another. The 5'-flanking regions in gf-2.8 and gf-3.8 contain recognizable sites of what are probably cis-acting elements but there is otherwise little if any significant similarity between them. In addition to putative TATA and CAAT boxes in the 5'-flanking regions of gf-2.8 and gf-3.8, there are AT-rich inverted-repeats, GC boxes, long purine-rich sequences, two 19-base pair direct-repeat sequences in gf-2.8, and a remarkably long (200-base pair) inverted-repeat sequence (approximately 90% homology) in gf-3.8. An 8% difference between the mature-protein coding regions in gf-2.8 and gf-3.8 is reflected by a corresponding 7% difference between the corresponding 201-residue proteins. Most significantly, the same 8% difference between the mature-protein coding regions in gf-2.8 and gf-3.8 is allied with no change whatever in a central part (61-151) of the encoded polypeptide sequences. It seems likely that this central, strongly conserved core in the germins is of first importance in the biochemical involvements of the proteins. When an equivalence is assumed between like amino acids, the gf-2.8 and gf-3.8 germins show significant (approximately 44%) similarity to spherulins 1a and 1b of Physarum polycephalum, a similarity that increases to approximately 50% in the conserved core of germin. Near the middle (87-96) of the conserved core in the germins is a rare PH(I/T)HPRATEI decapeptide sequence which is shared by spherulins (1a and 1b) and germins (gf-2.8 and gf-3.8). These similarities are discussed in the context of evidence which can be interpreted to suggest that the biochemistry of germins and spherulins is involved with cellular, perhaps cell-wall responses to desiccation, hydration, and osmotic stress.(ABSTRACT TRUNCATED AT 400 WORDS)     

Regulatory volume decrease in small intestinal crypts is inhibited by K+ and Cl- channel blockers.

Total crypt volume has been estimated by analysis of photographic images of intact viable crypts isolated from guinea-pig small intestine. Exposing these crypts to a hypotonic medium, led to transient swelling followed by regulatory volume decrease (RVD) in 12-20 min. RVD was blocked by inhibitors of K+ and Cl- conductance, suggesting that it occurs by activation of K+ and Cl- permeability pathways and loss of these ions.     

The effect of polyamines on tyrosine hydroxylase and L-Aromatic amino acid decarboxylase

The polyamines stimulated tyrosine hydroxylase in whole homogenates of bovine caudate nuclei approximately 2 fold. TheV _max forl-tyrosine increased by 2.3 fold while theK _m s forl-tyrosine and for the cofactor (DMPH₄) were unchanged.l-Aromatic amino acid decarboxylase from whole rat brain homogenate was stimulated by about 40% in the presence of polyamines. These findings suggest that increased polyamine levels associated with increased cellular synthetic activity can modify the synthesis of neurotransmitters.     

Thermal acclimation in the fresh water planarians,Dugesia tigrina and D. dorotocephala

The fecundity of two British populations of the freshwater crayfish Austropotamobius pallipes was examined. A number of maternal-size-related variables were correlated with counts of pleopodal eggs per female. Egg numbers did not decrease with increasing time from initial laying. Ovarian egg counts were considerably higher than expected pleopodal egg numbers. The influence of locational parameters is discussed and regional comparisons made.     

Juvenile dermatomyositis: medical,social and economic status in adulthood.

Eighteen adults were studied an average of 18.5 years after the diagnosis of juvenile dermatomyositis had been made. Persistent weakness was found in six patients and recurrent rash in the classic distribution in seven. Other clinical features present were Raynaud''s phenomenon, arthritis and subcutaneous nodules. Minor increases in the serum creatine phosphokinase level were noted in seven patients and did not correlate with the presence of weakness or rash. Educational achievement and employment status were better in this group than in a group of adults with juvenile rheumatoid arthritis or the general adult population of British Columbia. Significant residual disability related to calcinosis and flexion contractures was present in only three of the patients.     

Meiosis readiness in Lilium longiflorum “Croft”

It is proposed that anthers of Lilium longiflorum Croft approaching the end of premeiotic mitosis reach a state described as meiosis readiness after which cells in premeiotic prophase are unable to complete a mitotic division but despiralize to interphase and enter a meiotic division. Many of the laggard premeiotic cells begin despiralization before reaching an extremely contracted state of late prophase. Premeiotic despiralization is not, therefore, attributed to a deficiency in metaphase but to an inability of these cells to complete prophase. Premeiotic despiralization appears to be preceded by a slowing-down of prophase development. There is variation among anthers and anther regions in the onset of prophase retardation and meiosis readiness. It is suggested that meiosis readiness depends upon a gradual accumulation of meiosis-inducing substances in the cytoplasm of the premeiotic cells. It has not been determined whether the cells that undergo premeiotic despiralization give rise to the giant microsporocytes with shattered chromosomes observed at late prophase of meiosis.