Evolutionary steps of ecophysiological adaptation and diversification of ruminants: a comparative view of their digestive system

Summary A review is made of the ruminant digestive system in its morphophysiological variations and adaptations relating to foraging behaviour, digestive physiology, to interactions between plants and ruminants and to geographic and climatic diversity of ruminants' ecological niches. Evidence is provided for evolutionary trends from an extreme selectivity mainly for plant cell contents and dependence upon a fractionated fore- and hindgut fermentation, to an unselective intake of bulk roughage subjected to an efficient plant cell wall fermentation, mainly in the forestomachs. The review is based on detailed comparative morphological studies of all portions of the digestive system of 65 ruminant species from four continents. Their results are related to physiological evidence and to the classification of all extant ruminants into a flexible system of three overlapping morphophysiological feeding types: concentrate selectors (40%), grass and roughage eaters (25%) and intermediate, opportunistic, mixed feeders (35%). Several examples are discussed how ruminants of different feeding types are gaining ecological advantage and it is concluded that ruminants have achieved high levels of digestive efficiency at each evolutionary stage, (including well-documented seasonal adaptations of the digestive system) and that ruminant evolution is still going on. Deductions made from the few domesticated ruminant species may have, in the past, biased scientific evaluation of the free-ranging species' ecology. The main threat to a continuous ruminant evolution and diversity appears to be man's neglect for essential ecological interactions between wild ruminants and their specific habitats, which he alters or destroys.Abbreviations bw body weight - CS concentrate selector - DFC distal fermentation chamber (distended caecocolon) - GR grass and roughage eater - IM intermediate (mixed) feeder - PFC proximal fermentation chamber (ruminoreticulum/forestomachs) - RR Ruminoreticulum - SCFA Short-chain fatty acis (acetic, butyric, propionic acid set free by rumen bacteriae) - SE Surface enlargement (of absorptive mucosa) Supported by German Research Community grant DFG Ho 273/6Dedicated to Professor Dr. Dr. h.c. Dietrich Starck on the occasion of his 80th birthday     

Isolation and characterization of cDNA clones encoding the 17.9 and 8.1 kDa subunits of Photosystem I from Chlamydomonas reinhardtii

cDNA clones encoding two Photosystem I subunits of Chlamydomonas reinhardtii with apparent molecular masses of 18 and 11 kDa (thylakoid polypeptides 21 and 30; P21 and P30 respectively) were isolated using oligonucleotides, the sequences of which were deduced from the N-terminal amino acid sequences of the proteins. The cDNAs were sequenced and used to probe Southern and Northern blots. The Southern blot analysis indicates that both proteins are encoded by single-copy genes. The mRNA sizes of the two components are 1400 and 740 nucleotides, respectively. Comparison between the open reading frames of the cDNAs and the N-terminal amino acid sequences of the proteins indicates that the molecular masses of the mature proteins are 17.9 (P21) and 8.1 kDa (P30). Analysis of the deduced protein sequences predicts that both subunits are extrinsic membrane proteins with net positive charges. The amino acid sequences of the transit peptides suggest that P21 and P30 are routed towards the lumenal and stromal sides of the thylakoid membranes, respectively.Abbreviations OEE1, 2 and 3 oxygen evolution enhancer proteins 1, 2 and 3 - Rubisco ribulose bisphosphate carboxylase/oxygenase - PS photosystem - P21 and P30 C. reinhardtii thylakoid polypeptides 21 and 30     

Susceptibility of autologous target cells to lysis by lymphokine-activated effectors from interferon-α-treated chronic myelogenous leukaemia patients

Summary Chronic myelogenous leukemia (CML) patients in chronic phase display compromised lymphokine-activated killer (LAK) cell induction, which is partly restored after therapy with interferon . However, the relative resistance of the leukemic cells from these patients to autologous or allogeneic LAK lysis is not affected by this treatment. In an attempt to render CML cells more susceptible to lysis or cytostasis, they were precultured in serum-free medium with or without recombinant growth factors. In eight patients studied, interleukin-3 (IL-3) significantly enhanced the spontaneous short-term (6-day) proliferation of CML cells, with retention of ability to form colonies in methylcellulose. Culture in either medium alone or IL-3 led to a significant enrichment of CD14⁺ and CD33⁺ cells but to a reduction in CD34⁺ cells. In contrast, culture of the same cells in IL-2 (to generate autologous LAK activity) resulted in a loss of CD14⁺ and CD33⁺ as well as CD34⁺ cells but in a significant increase in CD3⁺ and CD56⁺ cells. Despite similarities in their phenotypes, IL-3 cultured cells but not those cultured in medium alone acquired susceptibility to lysis by the IL-2-cultured autologous LAK cells. These results may have significance for the design of novel combination immunotherapy in CML.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 120)     

Ultrastructural localization of WGA,RCA I,LFA and SBA binding sites in the seven-day-old mouse embryo

Summary Transglutaminases are Ca²⁺-dependent intra-and extracellular enzymes catalyzing the cross-linking between proteins and/or polyamines, thereby eliciting divergent physiological effects such as fibrin clot stabilization or hair follicle cross-linking. A secretory transglutaminase (EC 2.3.2.13) was isolated from the coagulating gland of the rat. The protein is highly glycosylated. A fraction purified to homogeneity was used as an antigen to raise polyclonal antibodies in rabbits. These antibodies were used to identify the secretion sites of the protein within the male accessory sex glands as well as to study the immunological relationships of the respective antigen within different organs of different species. In the rat, the coagulating gland and likewise the dorsal prostate gave a positive immunoreaction. In the guinea pig, a closely related protein was detected in the anterior prostate. No cross-reactivity was found with membrane-bound transglutaminase from liver, erythrocytes or blood clotting factor XIIIa. The intraluminal secretion of the aforementioned glands was only weakly stained. No secretory granules were observed in the glandular epithelium but instead bleb-like structures reminiscent of apocrine secretion. A slight background stain of the epithelium remained even in castrated animals where secretion is largely suppressed. The background stain is attributed to a tissue-type, membrane-bound, non-secretory transglutaminase that is not androgen dependent, but instead synthesized only after androgen deprivation.     

Atrial natriuretic peptide in the central nervous system of the rat

1. Studies of the presence of atrial natriuretic peptide immunoreactivity and receptor binding sites in the central nervous system have revealed unusual sites of interest. 2. As a result, numerous studies have appeared that indicate that brain atrial natriuretic peptide is implicated in the regulation of blood pressure, fluid and sodium balance, cerebral blood flow, brain microcirculation, blood-brain barrier function, and cerebrospinal fluid production. 3. Alteration of the atrial natriuretic peptide system in the brain could have important implications in hypertensive disease and disorders of water balance in the central nervous system.     

Poly-cis carotene pathway in the Scenedesmus mutant C-6D

The mutation of Scenedesmus obliquus strain C-6D is expressed in the dark only. Under these conditions, this strain synthesizes acyclic poly-cis carotenes. Cyclic carotenoids like -carotene or xanthophylls are absent. In the light the normal cyclic carotenes and xanthophylls are synthesized in the all-trans configuration. The poly-cis carotencs present in dark cultures have been analysed and quantitated. It could be shown that these poly-cis carotenes are identical with the poly-cis carotenes synthesized by the tomato mutant Lycopersicon esculentum var. Tangella. The poly-cis pathways, however, are different regulated in the two organisms. The tomato mutant accumulates prolycopene as the major carotene, whereas the mutant C-6D accumulates mainly pro--carotene. Furthermore, the mutation in Tangella is constitutive in light in contrast to Scenedesmus C-6D. Besides that, Scenedesmus C-6D synthesizes a further cis-carotene isomer of phytofluene as well as of -carotene. The configuration of these carotenes still have to be elucidated. The occurrence of this poly-cis carotene biosynthetic pathway by a mutation of only one enzyme, the phytoene desaturase which, however, is only expressed in darkness under heterotrophic conditions, is discussed.     

Construction of a yeast mutant lacking the mitochondrial nuclease.

The nuclear gene from Saccharomyces cerevisiae that encodes the major mitochondrial nuclease was cloned. Gene sequences were identified from a lambda gt11 library by antibodies specific to the mitochondrial nuclease. DNA from the phage recombinant was used to isolate the entire nuclease gene from a plasmid library. Yeast strains containing the nuclease gene on a multicopy plasmid vector overproduced mitochondrial nuclease 20-40 times relative to a wild-type strain. Strains containing a null allele of the nuclease gene lacked all traces of mitochondrial nuclease. Both cell types, however, were phenotypically wild-type indicating that the nuclease is not an essential enzyme for mitochondrial function. The locus encoding the mitochondrial nuclease is termed NUC1.     

Synthesis of 24-nor-5 beta-cholan-23-oic acid derivatives: a convenient and efficient one-carbon degradation of the side chain of natural bile acids

An efficient procedure for obtaining nor-bile acids from natural (C24) bile acids is described. Treatment of formylated bile acids with sodium nitrite in a mixture of trifluoroacetic anhydride with trifluoroacetic acid gives, through a "second order" Beckmann rearrangement, 24-nor-23-nitriles. These compounds, on alkaline hydrolysis, afford the corresponding nor-bile acids in high yields. The sequence was successfully applied to the synthesis of 3 alpha-hydroxy-24-nor-5 beta-cholan-23-oic (norlithocholic) acid, 3 alpha,6 alpha- (norhyodeoxycholic), 3 alpha,7 alpha- (norchenodeoxycholic), 3 alpha,7 beta- (norursodeoxycholic), and 3 alpha,12 alpha-dihydroxy-24-nor-5 beta-cholan-23-oic (nordeoxycholic) acids, as well as 3 alpha,7 alpha,12 alpha-trihydroxy-24-nor-5 beta-cholan-23-oic (norcholic) acid. 13C-NMR spectra of their methyl esters are reported. The procedure provides a more rapid alternative to the Barbier-Wieland degradation for shortening by one methylene group the side chain of natural (C24) bile acids.     

Ventrale Inzisuren bei paläozoischen Podocopida (Ostracoda) und ihre funktionelle Deutung

Ventral incisures, till now not really functionally interpreted, are described in three genera of the Family Pachydomellidae (Podocopida, Ostracoda). The functional meaning of these structures (respiration and locomotion when the carapace is closed, special behavior of reproduction or brood care, etc.) and resulting taxonomic conclusions are discussed in detail. All specimens were found in basinal faciès.