β-Cell Expansion for Therapeutic Compensation of Insulin Resistance in Type 2 Diabetes

Insulin resistance is the primary cause of type 2 diabetes. However, if compensated by increased insulin production, insulin resistance by itself does not lead to overt disease. Type 2 diabetes develops when this compensation is insufficient, due to defects in β-cell function and in regulation of the β-cell mass. β-Cell transplantation, as well as approaches that replenish or preserve the endogenous β-cell mass, may facilitate the treatment of type 2 diabetes in patients requiring exogenous insulin.     

Biochemistry and ultrastructure of serotonergic nerve endings in the lobster: serotonin and octopamine are contained in different nerve endings

In this article we report that the distribution of serotonin in the lobster nervous system parallels the distribution of octopamine and that the same tissues that contain endogenous serotonin can synthesize it from tryptophan. Octopamine and serotonin are highly concentrated in a neurosecretory region of the second thoracic roots in association with a group of neurosecretory cells. The roots possess separate high-affinity uptake systems for both serotonin and tryptophan. Radioactive serotonin, accumulated in tissues during incubations with either tritiated serotonin or tritiated tryptophan, can be released, in a calcium-dependent manner, by depolarization with potassium. A detailed morphological examination of the second thoracic roots shows four distinct categories of nerve endings in the vicinity of the neurosecretory cells. Octopamine is synthesized in one of these types of endings and serotonin in another. The high-affinity uptake systems for serotonin and tryptophan are found only in association with the endings that make serotonin. These endings and all the biochemical parameters of serotonin metabolism in the roots are selectively destroyed by previous injection of animals with the neurotoxin 5,7-dihydroxytryptamine.     

The effect of pollen source on seed traits and dispersability in the heterocarpic annual Crepis sancta

不同花粉来源对一年生植物种子性状和扩散能力的影响 与扩散有关的性状进化和表达与其他生活史功能交织在一起，并在各种生理约束条件下表现出 来。这种关系可以在近交水平和扩散性之间得到预测，而且在解剖学和个体发育上联系在一起，从而使 某个选择压力可能影响另外的一个。虽然近交对生殖成功和扩散策略的影响都引起了广泛关注，但只有 少数研究同时考虑了这两者。此外，此类研究通常依赖于繁殖和扩散的表示：使用自交与异源杂交表示繁殖水平，使用扩散比表示扩散策略。本研究利用菊科Crepis sancta的授粉实验，以两种不同的方式扩展 繁殖和扩散的二分表示法。首先，我们使用授粉处理来表示一种统一连续体，即从亲缘授粉的自交到距离较远的邻居授粉。其次，我们不仅测量了繁殖成功率和扩散比，还测量了一整套连续的与形态和扩散相关的性状。研究结果显示，头状花序的比例，以及扩散的和非扩散的瘦果在自花传粉处理中都显著低于异源杂交处理。尽管自花授粉的植物很少产生不扩散的种子，但花粉来源对扩散比的影响统计上不显著。瘦果的生物量随亲本植物之间的距离增加而增加，但冠毛宽度没有增加，从而导致授粉对下落速度的影响不显着。总之，花粉来源主要影响与生殖产量有关的性状，但对主要与扩散有关的性状没有显著影响。繁殖和扩散性状对花粉来源变化响应的这种差异表明，与扩散有关的选择可能很弱和/或被其他因素所掩盖。