Mutations in LMF1 cause combined lipase deficiency and severe hypertriglyceridemia

Hypertriglyceridemia is a hallmark of many disorders, including metabolic syndrome, diabetes, atherosclerosis and obesity. A well-known cause is the deficiency of lipoprotein lipase (LPL), a key enzyme in plasma triglyceride hydrolysis. Mice carrying the combined lipase deficiency (cld) mutation show severe hypertriglyceridemia owing to a decrease in the activity of LPL and a related enzyme, hepatic lipase (HL), caused by impaired maturation of nascent LPL and hepatic lipase polypeptides in the endoplasmic reticulum (ER). Here we identify the gene containing the cld mutation as Tmem112 and rename it Lmf1 (Lipase maturation factor 1). Lmf1 encodes a transmembrane protein with an evolutionarily conserved domain of unknown function that localizes to the ER. A human subject homozygous for a deleterious mutation in LMF1 also shows combined lipase deficiency with concomitant hypertriglyceridemia and associated disorders. Thus, through its profound effect on lipase activity, LMF1 emerges as an important candidate gene in hypertriglyceridemia.     

Early life history of the sheepnose (Plethobasus cyphyus) (Mollusca: Bivalvia: Unionoida)

Managing a rare species can be improved with knowledge of its natural history. The sheepnose (Plethobasus cyphyus) is a freshwater mussel recently listed by the US as federally endangered. We used standard methods to study P. cyphyus brooding behaviour, host fishes in the laboratory and under natural conditions, and glochidial morphology. We monitored a population of P. cyphyus in the Chippewa River, WI during spring and summer 2007–2009 and 2011 and found brooding animals between mid-May and early August. Gravid individuals ranged between 5 and 27 yr (mean age ± 1 s.d. = 13 ± 4 yr). Plethobasus cyphyus brooded glochidia in outer gills, which varied in colour from red, orange, pink, cream, or white. We observed mature glochidia more commonly in individuals with cream or white gills and these glochidia were released in a clear, adhesive, mucus matrix. In laboratory trials we found several minnow and topminnow species (29 spp.) served as productive suitable native hosts. The mean number of juvenile mussels released per cyprinid per day was significantly higher for trials conducted at 22–25°C compared with those at 18–20°C, and 83% of trials conducted at 18–20°C using suitable host species produced no juveniles. Glochidia had a unique outline and shell morphometrics that distinguished P. cyphyus from seven other Chippewa River mussel species that produce similar sized glochidia. Using morphometrics we determined that mimic shiners (Notropis volucellus) were natural hosts for P. cyphyus, round pigtoe (Pleurobema sintoxia), and Wabash pigtoe (Fusconaia flava). Releasing mucus-bound glochidia has evolved in a variety of mussel species and may be more common than is currently realized. Our data show that P. cyphyus is a cyprinid host specialist, and propagation efforts for this species can be strengthened through improved access to mature glochidia by using females with cream-coloured gills and increased juvenile production through warmer fish holding temperatures.     

Induction of functional retinal projections to the somatosensory system

Optic axons can be induced to form permanent, retinotopic connections in the auditory (medial geniculate, MG) and somatosensory (ventrobasal, VB) nuclei of the Syrian hamster thalamus; this occurs when the principal targets of retinofugal axons are ablated in newborn hamsters and alternative terminal space is created by partial deafferentation of MG or VB. The experimentally induced retinal projection to the somatosensory nucleus occurs by the stabilization of an early, normally transient projection. The present study was undertaken to determine whether the anomalous, stabilized retino-VB projection is functional. Newborn hamsters were operated on to produce permanent retino-VB projections and when the animals were mature, neurophysiological recordings were made in the cortical targets of VB, the first and second somatosensory cortices (SI and SII, respectively). Visual stimulation within well-defined receptive fields reliably evoked multi-unit responses in SI and SII of operated, but not normal hamsters. The representations of the visual field in SI and SII showed a partially retinotopic organization. These results demonstrate that optic tract axons can form functional synapses in the thalamic somatosensory nucleus, and suggest that neural structures which normally process information specific to one sensory modality have the potential to mediate function for other modalities.     

Mite parasitism of mosquitoes in central Wyoming

Parasitic larval mites including Thyasides sphagnorum were collected from mosquitoes captured in New Jersey light traps over a period of 6 yr and from landings during 1 collecting season in Natrona County, Wyoming. Overall mite prevalence on mosquitoes was 0.42% and abundance was 0.76%. Prevalence on Aedes dorsalis was significantly greater than on other host species. Comparison of light trap data and landing data suggests that parasitized mosquitoes may seek blood meals more frequently than non-parasitized mosquitoes.     

Radio harness system for bobcat kittens

Eight bobcat kittens were fitted with a specially designed harness system supporting a radio transmitter. These kittens were the youngest known to be radio-instrumented. This system was used successfully through two seasons, from June 1989 to January 1991. Litters of kittens were located soon after birth for weighing, marking, and aging (by tooth eruption). During the first year when kittens were at least eight weeks old and six weeks old the second year, attempts were made to radio-instrument kittens in each litter. This harness system allowed litters to be located periodically until their death or dispersal. We were able to collect important data during the most crucial and least known weeks of the lives of bobcat kittens.     

At least two toxins are involved inEscherichia coli mastitis

Summary Culture filtrate ofEscherichia coli produces changes in the bovine udder identical to those seen in experimental infections with the same organism.E. coli endotoxin produces an acute inflammatory response but none of the cell damage induced by culture filtrate. It appears therefore that at least 2 toxins are involved in the disease.Acknowledgments. We are grateful to Mrs K. Wells, Miss H. Meads and Miss A. Ashford for technical assistance.     

GTP-dependent twisting of dynamin implicates constriction and tension in membrane fission

Dynamin, a crucial factor in endocytosis, is a member of a family of GTPases that participates in membrane fission. It was initially proposed to act as a machine that constricts and cuts the neck of nascent vesicles in a GTP-hydrolysis-dependent reaction, but subsequent studies suggested alternative models. Here we monitored the effect of nucleotides on dynamin-coated lipid tubules in real time. Addition of GTP, but not of GDP or GTP-gammaS, resulted in twisting of the tubules and supercoiling, suggesting a rotatory movement of the helix turns relative to each other during GTP hydrolysis. Rotation was confirmed by the movement of beads attached to the tubules. Twisting activity produced a longitudinal tension that was released by tubule breakage when both ends of the tubule were anchored. Fission also occurred when dynamin and GTP were added to lipid tubules that had been generated from liposomes by the motor activity of kinesin on microtubules. No fission events were observed in the absence of longitudinal tension. These findings demonstrate a mechanoenzyme activity of dynamin in endocytosis, but also imply that constriction is not sufficient for fission. At the short necks of endocytic vesicles, other factors leading to tension may cooperate with the constricting activity of dynamin to induce fission.     

HDTMAB改性蒙脱石对苯酚的吸附实验研究

以阳离子表面活性剂十六烷基三甲基溴化铵(HDTMAB)为柱撑剂对怀俄明钠基蒙脱石进行改性,获得了不同质量浓度的有机改性黏土(0.5～2 5CEC).通过对改性蒙脱石吸附苯酚的XRD、TEM和热重分析的实验研究,发现改性后蒙脱石的层间距明显增大.实验结果表明随着改性活性剂质量浓度的加大,HDTMAB有机离子逐渐由单层变为双层直至三层.有机蒙脱石去除水溶液中苯酚的能力也相应地得到了很大的提高,吸附效果明显增强.     

草酸盐矿物的Raman和红外光谱特征研究:寻找行星生命的有效方法

草酸盐矿物的形成可以用来证明苔藓、真菌等低级生物的存在. 系统研究了一水草酸钙石、二水草酸钙石、草酸铜石、草酸铁石、草酸镁石、草酸钠石和草酸胺石等7种草酸盐矿物的Raman和红外光谱特征. 研究表明, 草酸盐矿物的CO Raman伸缩振动峰与阳离子种类有关, 二水草酸钙石、草酸铜石、草酸镁石、草酸钠石的CO Raman伸缩振动峰依次是1468, 1489, 1471, 1456 cm^-1. 除草酸胺石外, 只有Raman和红外光谱特征能够证明这些草酸盐矿物的络合特性. 还对水的OH 伸缩振动的光谱学特征进行了测定和分析, 用来区分草酸钙石中是否含有结晶水及结晶水的含量. 结果的重要性在于可以用振动光谱技术来鉴定赋存在岩石表层的草酸盐矿物, 从而用于证明其他行星(如火星)上是否有生命或曾经有生命存在.