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As a key enzyme for nitrogen assimilation in plant, glutamine synthetase (TaGS) is encoded by 12 genes in common wheat (Triticum aestivum L.), namely TaGS1;1-6A/6B/6D, TaGS1;2-4A/4B/4D, TaGS1;3-4A/4B/4D, and TaGS2-2A/2B/2D. Transcripts of TaGS genes were obtained using the single molecular sequencing technology, and the results showed that TaGS1;1-6A had one alternative splicing (AS) version of transcripts and TaGS1;1-6B had two AS versions. Compared with the TaGS encoded by normal transcript, TaGS1;1-6A-1 lacked part of the Gln_synt_N domain, and TaGS1;1-6B-3 lacked the Gln_synth_gly_rich_ site domain; TaGS1;1-6B-4 was a new AS event, and encoded a truncated GS without Gln_synth_gly_rich_site and Gln_synth_ cat_dom domain. The relative expression level of TaGS alternative splicing transcripts of wheat cultivars with different nitrogen use efficiencies showed that the relative expression level of TaGS1;1-6A-1 in leaves of YM49 (N-efficient) was significantly higher than that of XN509 (N-inefficient), and increased with the increase of nitrogen supply. In roots, the relative expression of TaGS1;1-6A-1 increased with the increase of nitrogen supply in YM49, but decreased in XN509. TaGS1;1-6B-3 showed a similar expression trend in YM49 and XN509, and high concentration of NO3- promoted the expression of TaGS1;1-6B-3 in leaves while inhibited in roots. High concentration of NH4+ inhibited the expression of TaGS1;1-6B-3 in leaves, but had little effect in roots. TaGS1;1-6B-4 was mainly expressed under low nitrogen condition, and its expression in roots of YM49 was not affected by NH4+ supply. Understanding the AS transcript versions of TaGS genes is helpful to illustrate the functions of TaGS isozymes in nitrogen metabolism of wheat. [ABSTRACT FROM AUTHOR]

Abstract Background The human KALRN gene, which encodes a complex, multifunctional Rho GDP/GTP exchange factor, has been linked to cardiovascular disease, psychiatric disorders and neurodegeneration. Examination of existing Kalrn knockout mouse models has focused only on neuronal phenotypes. However, Kalirin was first identified through its interaction with an enzyme involved in the synthesis and secretion of multiple bioactive peptides, and studies in C.elegans revealed roles for its orthologue in neurosecretion. Results We used a broad array of tests to evaluate the effects of ablating a single exon in the spectrin repeat region of Kalrn (KalSRKO/KO); transcripts encoding Kalrn isoforms containing only the second GEF domain can still be produced from the single remaining functional Kalrn promoter. As expected, KalSRKO/KO mice showed a decrease in anxiety-like behavior and a passive avoidance deficit. No changes were observed in prepulse inhibition of acoustic startle or tests of depression-like behavior. Growth rate, parturition and pituitary secretion of growth hormone and prolactin were deficient in the KalSRKO/KO mice. Based on the fact that a subset of Kalrn isoforms is expressed in mouse skeletal muscle and the observation that muscle function in C.elegans requires its Kalrn orthologue, KalSRKO/KO mice were evaluated in the rotarod and wire hang tests. KalSRKO/KO mice showed a profound decrease in neuromuscular function, with deficits apparent in KalSR+/KO mice; these deficits were not as marked when loss of Kalrn expression was restricted to the nervous system. Pre- and postsynaptic deficits in the neuromuscular junction were observed, along with alterations in sarcomere length. Conclusions Many of the widespread and diverse deficits observed both within and outside of the nervous system when expression of Kalrn is eliminated may reflect its role in secretory granule function and its expression outside of the nervous system.

Abstract Background The long-term effects of cocaine on behavior are accompanied by structural changes in excitatory glutamatergic synapses onto the medium spiny neurons of the striatum. The Kalrn gene encodes several functionally distinct isoforms; these multidomain guanine nucleotide exchange factors (GEFs) contain additional domains known to interact with phosphatidylinositides as well as with a number of different proteins. Through their activation of Rho proteins and their interactions with other proteins, the different Kalirin isoforms affect cytoskeletal organization. Chronic exposure of adult male rodents to cocaine increases levels of Kalirin 7 in the striatum. When exposed chronically to cocaine, mice lacking Kalirin 7, the major adult isoform, fail to show an increase in dendritic spine density in the nucleus accumbens, show diminished place preference for cocaine, and exhibit increased locomotor activity in response to cocaine. Results The use of alternate promoters and 3'-terminal exons of the mouse Kalrn gene were investigated using real-time quantitative polymerase chain reaction. While the two most distal full-length Kalrn promoters are used equally in the prefrontal cortex, the more proximal of these promoters accounts for most of the transcripts expressed in the nucleus accumbens. The 3'-terminal exon unique to the Kalirin 7 isoform accounts for a greater percentage of the Kalrn transcripts in prefrontal cortex than in nucleus accumbens. Western blot analyses confirmed these differences. Chronic cocaine treatment increases usage of the promoter encoding the Δ-Kalirin isoforms but does not alter full-length Kalirin promoter usage. Usage of the 3'-terminal exon unique to Kalirin 7 increases following chronic cocaine exposure. Conclusions Kalrn promoter and 3'-terminal exon utilization are region-specific. In the nucleus accumbens, cocaine-mediated alterations in promoter usage and 3'-terminal exon usage favor expression of Kalirin 7 and Δ-Kalirin 7. The Δ-isoform, which lacks a Sec14p domain and four of the nine spectrin-like repeats found in full-length Kalirin isoforms, increases spine headsize without increasing dendritic spine numbers. Thus cocaine-mediated changes in alternative splicing of the Kalrn gene may contribute importantly to the behavioral, morphological and biochemical responses observed.

Neuropeptides and peptide hormones play a crucial role in integrating the many factors that affect physiologic and cognitive processes. The potency of many of these peptides requires an amidated amino acid at the C‐terminus; a single enzyme, peptidylglycine α‐amidating monooxygenase (PAM), catalyzes this modification. Anxiety‐like behavior is known to be altered in mice with a single functional Pam allele (Pam+/−) and in mice unable to express Pam in excitatory forebrain neurons (PamEmx1‐cKO/cKO) or in cardiomyocytes (PamMyh6‐cKO/cKO). Examination of PAM‐positive and glutamic acid decarboxylase 67 (GAD)‐positive cells in the amygdala of PamEmx1‐cKO/cKO mice demonstrated the absence of PAM in pyramidal neurons and its continued presence in GAD‐positive interneurons, suggestive of altered excitatory/inhibitory balance. Additional behavioral tests were used to search for functional alterations in these cell‐type specific knockout mice. PamEmx1‐cKO/cKO mice exhibited a less focused search pattern for the Barnes Maze escape hole than control or PamMyh6‐cKO/cKO mice. While wildtype mice favor interacting with novel objects as opposed to familiar objects, both PamEmx1‐cKO/cKO and PamMyh6‐cKO/cKO mice exhibited significantly less interest in the novel object. Since PAM levels in the central nervous system of PamMyh6‐cKO/cKO mice are unaltered, the behavioral effect observed in these mice may reflect their inability to produce atrial granules and the resulting reduction in serum levels of atrial natriuretic peptide. In the sociability test, male mice of all three genotypes spent more time with same‐sex stranger mice; while control females showed no preference for stranger mice, female PamEmx1‐cKO/cKO mice showed preference for same‐sex stranger mice in all trials. [ABSTRACT FROM AUTHOR]