Sieve areas in fossil Phloem

Phloem tissue of the Pennsylvanian fern Etapteris is described from permineralized specimens. Sieve elements possess regularly aligned sieve areas containing pores on the radial walls. The presence of these structures provides a basis for comparison with the phloem of living ferns.     

The fine structure of fossil plant cell walls

The cell walls of sieve elements in the primary phloem of the Carboniferous fern Tubicaulis contain structural features that morphologically resemble cellulose microfibrils in extant plants. This may be the oldest example of distinct fibrillar structures in the fossil record. The possible identity and significance of these features are discussed and their structure is compared with that of cell walls in other fossil and extant plants.     

戊型肝炎病毒研究新进展

戊型肝炎病毒(hepatitis Evirus,HEV)是非甲非乙型急性肝炎的病原体,主要经粪-口途径传播,也有报道可以通过血液传播。戊型肝炎在亚洲、非洲及美洲的墨西哥等发展中国家常呈爆发流行,我国1986-1988年在新疆曾经发生戊型肝炎暴发流行[1],而在包括发达国家在内的世界各地呈散在传     

Association with TGF‐β1 Gene Polymorphisms and Reproductive Performance of Large White Pig

As a multifunctional cytokine, transforming growth factor‐beta1 (TGF‐β1) was detected in the utero‐placental interface during early pregnancy in the pig and believed to enhance trophoblast attachment to the endometrium. In this experiment, we selected TGF‐β1 as the candidate gene affecting litter size in pigs. Four polymorphic loci of TGF‐β1 gene were found by PCR‐SSCP (single‐strand conformation polymorphism) in Large white sows (n = 567): C→T mutation at 33nt in the intron 4; G→A mutation at 179nt in the intron 6; C→T mutation at 1043nt in the intron 6; GG→AA linkage mutations at 2490nt and 2494nt respectively. We haplotyped these SNPs as: CGCAA (denote as P) and TATGG (denote as K). The effects of three haplotypic combinations (HCs) of PP, PK and KK on litter sizes were investigated by a linear model. It was found that for the first parity litters, the least squares mean for total number born (TNB) of KK was 1.02 piglets/litter, higher than that of PK (p < 0.05), 0.49 piglets/litter higher than that of PP (p > 0.1). There were no significant differences between HCs on the second parity. The result indicated that KK HCs was significantly associated with pig litter size.     

Impact of EasiFlo cottonseed on feed intake, apparent digestibility, and rate of passage by goats fed a diet containing 45% hay

EasiFlo cottonseed (ECS), produced by coating whole cottonseed (WCS) with cornstarch to simplify handling and mixing with other ingredients, is marketed commercially. The objective of this trial was to determine its digestibility by small ruminants. Four mature Nubian wether goats, in a 4 x 4 Latin square arrangement of treatments, were fed diets that contained about 45% bermudagrass hay (BGH) plus 0, 15.7, 32.7, or 50.3% ECS, with the ECS replacing corn and soybean meal (2:1 ratio) in the concentrate portion of the diet. Feed intakes and digestibility of components were measured, and passage rate was estimated using ytterbium-marked BGH. Dry matter intake decreased at an increasing rate (P < 0.01) as ECS or fat concentration in the diet increased. Digestibility was linearly depressed (P= 0.003) as ECS replaced corn and soybean meal in the diet, primarily due to depressed (P < 0.05) digestibility of NDF, ADF, and nonfibrous carbohydrates (NFC). In contrast, fat digestibility tended to increase (P = 0.11) linearly and N utilization was increased (P = 0.04) linearly as ECS concentration was increased. Passage kinetics were not altered. Based on regression estimates of TDN for BGH and literature values of TDN for other feed ingredients, the total digestible nutrient content of ECS for mature goats fed a 45% roughage diet was estimated to be 78.0 +/- 9.1%, a value quite similar to that (77.2%) proposed for whole cottonseed for large ruminants by NRC tables. Low digestibility of fiber (under 10% of NDF) and of nonfibrous carbohydrate limits the digestibility of DM and energy from ECS.