候鸟迁徙过程中"雄性早现"的六种假说及未来研究热点

"雄性早现"(protandry)是指雄性相对于雌性更早进入繁殖状态或更早到达繁殖地的现象.该文针对候鸟的雄性比雌性在春季时更早到达繁殖地这一现象,介绍了雄性早现的6种假说,即等级优势(rank advantage)假说、敏感性(susceptibility)假说、限制性(constraint)假说、交配机会(mate opportunity)假说、等待代价(waiting cost)假说和配偶选择(mate choice)假说,并通过近年来的研究证据阐述了上述假说对解释候鸟雄性早现的适用性.此外,对鸟类雄性早现未来研究中可能的热点问题做了展望.     

cDNA sequence and tissues expression analysis of lipoprotein lipase from common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> Var. Jian)

A full-length cDNA coding lipoprotein lipase (LPL) was cloned from liver of adult common carp (Cyprinus carpio Var. Jian) by RT-PCR and rapid amplification of cDNA ends (RACE) approaches. The cDNA obtained was 2,411 bp long with a 1,524 bp open reading frame (ORF) encoding 507 amino acids. This amino acid sequence contains two structural regions: N-terminus (24–354 residues) and C-terminus (355–507 residues). Before N-terminus, 1–23 residues is signal peptide, 6–23 residues is transmembrance helix. At N-terminus, some conversed functional sites were found, including two N-linked glycosylation sites Asn⁴¹ and Asn⁸⁸; one catalytic triad Ser¹⁷⁴, Asp¹⁹⁸ and His²⁸³; one conserved heparin-binding site Arg³²¹ to Arg³²⁴ (RKNR); eight cysteines residues Cys⁶⁹ and Cys⁸², Cys²⁵⁸ and Cys²⁸¹, Cys³⁰⁶ and Cys³²⁵, Cys³¹⁷ and Cys³²⁰ which are involved in four disulfide bridges; one polypeptide “lid” that participates in substrate specificity. At C-terminus, Asn⁴⁰¹ is another N-linked glycosylation site, and Trp⁴³⁴ and Trp⁴³⁵ (WW) is lipid-binding site. The amino acid sequence has a high similarity, and shows similar structural features to LPL of other species. Tissue distribution of LPL mRNA in liver, head kidney, mesenteric adipose tissue, heart and white muscle of common carp was analyzed by semi-quantitative RT-PCR method using β-actin gene as internal control. The result showed that the expressions of LPL mRNA were detected in all examined tissues of common carp. The expression levels of LPL in the mesenteric adipose tissue was highest among these tissues, following in liver and head kidney, and the lowest expression was found in heart and white muscle.     

Population genetic analysis of 6 Y-STR loci in Chinese northwestern Qinchuan yellow cattle breed

Six Y-STR loci (UMN0929, UMN0108, UMN0920, INRA124, UMN2404 and UMN0103) were analyzed using 576 healthy and unrelated males and 10 females of the Qinchuan cattle population in Chinese Shaanxi Province. Allele frequency, gene diversity, the polymorphic information content, and the number of effective gene were calculated. All loci were in accordance with the Hardy–Weinberg equilibrium (P > 0.05). The population data were compared with published data of other cattle breeds, suggesting that Qinchuan cattle were originated primarily from Bos Taurus. Results are valuable for individual identification, paternity testing, and origin analysis of Qinchuan cattle breed.     

5-Hydroxydecanoate and coenzyme A are inhibitors of native sarcolemmal KATP channels in inside-out patches

Background

5-Hydroxydecanoate (5-HD) inhibits preconditioning, and it is assumed to be a selective inhibitor of mitochondrial ATP-sensitive K⁺ (mitoK_ATP) channels. However, 5-HD is a substrate for mitochondrial outer membrane acyl-CoA synthetase, which catalyzes the reaction: 5?HD + CoA + ATP → 5-HD-CoA (5-hydroxydecanoyl-CoA) + AMP + pyrophosphate. We aimed to determine whether the reactants or principal product of this reaction modulate sarcolemmal K_ATP (sarcK_ATP) channel activity.

Methods

Single sarcK_ATP channel currents were measured in inside-out patches excised from rat ventricular myocytes. In addition, sarcK_ATP channel activity was recorded in whole-cell configuration or in giant inside-out patches excised from oocytes expressing Kir6.2/SUR2A.

Results

5-HD inhibited (IC₅₀ ∼ 30 μM) K_ATP channel activity, albeit only in the presence of (non-inhibitory) concentrations of ATP. Similarly, when the inhibitory effect of 0.2 mM ATP was reversed by 1 μM oleoyl-CoA, subsequent application of 5-HD blocked channel activity, but no effect was seen in the absence of ATP. Furthermore, we found that 1 μM coenzyme A (CoA) inhibited sarcK_ATP channels. Using giant inside-out patches, which are weakly sensitive to “contaminating” CoA, we found that Kir6.2/SUR2A channels were insensitive to 5-HD-CoA. In intact myocytes, 5-HD failed to reverse sarcK_ATP channel activation by either metabolic inhibition or rilmakalim.

General significance

SarcK_ATP channels are inhibited by 5-HD (provided that ATP is present) and CoA but insensitive to 5-HD-CoA. 5-HD is equally potent at “directly” inhibiting sarcK_ATP and mitoK_ATP channels. However, in intact cells, 5-HD fails to inhibit sarcK_ATP channels, suggesting that mitochondria are the preconditioning-relevant targets of 5-HD.     

Iridoids from the roots of Triosteum pinnatifidum

A chemical investigation of the roots of Triosteum pinnatifidum led to the isolation of 10 iridoids, elucidated as triohimas A–C, naucledal, secologanin dimethyl acetal, grandifloroside, sweroside, loganin, vogeloside and (E)-aldosecologanin. Most of the compounds were derived from loganin or secologanin with a glucose moiety at C-1 position. The results indicate a close relationship between the two genera Triosteum and Lonicera, and support the viewpoint that the iridoids derived from loganin or secologanin could be the chemotaxonomic markers of the Caprifoliaceae family.     

The search for an optimal DNA, RNA, and protein detection by in situ hybridization, immunohistochemistry, and solution-based methods

Clinical trials and correlative laboratory research are increasingly reliant upon archived paraffin-embedded samples. Therefore, the proper processing of biological samples is an important step to sample preservation and for downstream analyses like the detection of a wide variety of targets including micro RNA, DNA and proteins. This paper analyzed the question whether routine fixation of cells and tissues in 10% buffered formalin is optimal for in situ and solution phase analyses by comparing this fixative to a variety of cross linking and alcohol (denaturing) fixatives. We examined the ability of nine commonly used fixative regimens to preserve cell morphology and DNA/RNA/protein quality for these applications. Epstein-Barr virus (EBV) and bovine papillomavirus (BPV)-infected tissues and cells were used as our model systems. Our evaluation showed that the optimal fixative in cell preparations for molecular hybridization techniques was "gentle" fixative with a cross-linker such as paraformaldehyde or a short incubation in 10% buffered formalin. The optimal fixatives for tissue were either paraformaldehyde or low concentration of formalin (5% of formalin). Methanol was the best of the non cross-linking fixatives for in situ hybridization and immunohistochemistry. For PCR-based detection of DNA or RNA, some denaturing fixatives like acetone and methanol as well as "gentle" cross-linking fixatives like paraformaldehyde out-performed other fixatives. Long term fixation was not proposed for DNA/RNA-based assays. The typical long-term fixation of cells and tissues in 10% buffered formalin is not optimal for combined analyses by in situ hybridization, immunohistochemistry, or--if one does not have unfixed tissues--solution phase PCR. Rather, we recommend short term less intense cross linking fixation if one wishes to use the same cells/tissue for in situ hybridization, immunohistochemistry, and solution phase PCR.     

Compatibility of neural stem cells with functionalized self-assembling peptide scaffold <Emphasis Type="Italic">in vitro</Emphasis>

In this study, we evaluated the behavior of neural stem cells (NSCs) using a new peptide hydrogel scaffold named IKVAVmx, which was made by mixing self-assembling peptide RADA16 and designer peptide RADA16-IKVAV solutions. NSCs derived from rat cerebral cortex were culture-expanded in neuorobasal medium and seeded on the RADA16 and IKVAVmx hydrogels. Cells could penetrate the hydrogels and form a 3D cellular network. Compared to pure RADA16 scaffold, we found that IKVAVmx scaffold significantly promoted cell proliferation and stimulated cell migration into the 3D scaffold. Moreover, Immunocytochemistry and Western blot analysis indicated that the differentiation ratio of neurons from NSCs in IKVAVmx scaffold was higher than that in pure RADA16 scaffold. These results suggested that this new hydrogel scaffold provided an ideal substrate for NSCs 3D culture and suggested its further application for neural tissue engineering.