Intestinal Mucus Protects Giardia lamblia from Killing by Human Milk1

We have previously shown that nonimmune human milk kills Giardia lamblia trophozoites in vitro. Killing requires a bile salt and the activity of the milk bile salt-stimulated lipase. We now show that human small-intestinal mucus protects trophozoites from killing by milk. Parasite survival increased with mucus concentration, but protection was overcome during longer incubation times or with greater milk concentrations. Trophozoites preincubated with mucus and then washed were not protected. Protective activity was associated with non-mucin CsCl density gradient fractions. Moreover, it was heat-stable, non-dialyzable, and non-lipid. Whereas whole mucus inhibited milk lipolytic activity, protective mucus fractions did not inhibit the enzyme. Furthermore, mucus partially protected G. lamblia trophozoites against the toxicity of oleic acid, a fatty acid which is released from milk triglycerides by lipase. These studies show that mucus protects G. lamblia both by inhibiting lipase activity and by decreasing the toxicity of products of lipolysis. The ability of mucus to protect G. lamblia from toxic lipolytic products may help to promote intestinal colonization by this parasite.     

The lower jaw of Morganucodon

The genus Morganucodon is found in Yunnan, China, in normal (non-karstic) sedimentary deposits (Lufeng beds) of probable Rhaetian age; and in Wales in karstic deposits in the Carboniferous Limestone. These latter deposits cannot be younger than Sinnemurian or older than Rhaetic.
A new suborder–Morganucodonta–of the Triconodonta is created for Morganucodon and its allies. Morganucodon and Eozostrodon are not synonyms.
The lower jaw of Morganucodon resembles closely that of an advanced cynodont, except for the presence of a squamosal-dentary joint in the former. There was no reduction in the functional importance of the reptilian (quadrate-articular) jaw-joint in passing from the cynodont condition to that of Morganucodon.
The mechanism of shearing is discussed. The action of the cheek-teeth is pure shear. Primarily, the function of the squamosal-dentary articulation was to resist couples produced by the shearing, thus primitively, the presence of efficient shearing cheek-teeth is associated with a squamosal-dentary articulation.
The skull of Morganucodon will be described in a later paper.     

Attachment of Entamoeba histolytica to Glass in a Defined Maintenance Medium: Specific Requirement for Cysteine and Ascorbic Acid*

SYNOPSIS. Cysteine and ascorbic acid were previously shown to be required by Entamoeba histolytica trophozoites for attachment to glass, elongation, and ameboid movement as well as for short-term (12–24 h) survival in a balanced salt solution containing bovine serum albumin and a vitamin solution (Maintenance Medium 1). If the only function of cysteine and ascorbate was to decrease the redox potential, other reducing agents should be effective. However, the requirement for cysteine in the presence of ascorbic acid was highly specific. Equally effective were D- and L-cysteine; however, of many other compounds tested, only thioglycolic acid, ascorbic acid, or L-cystine (in decreasing order) were somewhat active. Under N₂ atmosphere, cysteine and ascorbic acid were still required, although their concentrations could be halved. The ability to attach in the maintenance medium was irreversibly lost after only 5 min of cysteine-ascorbic acid deprivation; however, there was no decrease in viability when the amebae were transferred to growth medium within 30 min. Cysteine thiol groups in the medium were oxidized rapidly regardless of the concentration of ascorbic acid or the presence of amebae; however, ascorbic acid prolonged attachment of amebae.     

A demographic comparison of two Nordic populations of Greylag Geese Anser anser

Greylag Geese Anser anser have been neck-banded on an annual basis in Scania, southern Sweden since 1984 and in Norway since 1986 as part of a Nordic Greylag project. This has yielded a large database of resightings, which we used here to estimate and compare survival rates between the two populations by means of mark–recapture models. Estimated adult survival was sex-dependent in the Scanian population, probably a result of differential neck band retention rates in this population. Mean juvenile survival was about 12% higher in the Scanian population (0.603 vs. 0.485). Adult survival in the Norwegian population was 0.728 (males 0.733; females 0.725), and in males and females from the Scanian population was 0.711 (0.752 after accounting for higher neck band loss in males) and 0.771, respectively. Over the course of the study, juvenile survival in the Scanian population increased substantially, and adult survival was constant, whereas both these parameters declined in the Norwegian population. This study demonstrates that the two Nordic populations are demographically distinct and gives further support to the notion that they should be treated as separate management units. The decline of 10% in adult survival in the Norwegian population, the cause of which still remains uncertain, is likely to have had a major impact on the growth of this population.     

The delimitation of the tribe Vicieae (Leguminosae) and the relationships of Cicer L.

A survey of morphological, anatomical, karyological and chemical characters has been carried out, centred on the Vicieae but extending to the neighbouring tribes Trifolieae and Ononideae. The results show that Cicer , traditionally a member of the Vicieae, has more in common with genera of the Trifolieae and Ononideae than with the rest of the Vicieae. It is proposed that Cicer should be removed from the Vicieae and recognized as the monogeneric tribe Cicereae Alef. The tribe Vicieae sensu stricto, a well-defined natural group, is delimited and described. Phylogenetic relationships of the Cicereae are discussed.