A Survey of Birds Odorous or Unpalatable to Humans: Possible Indications of Chemical Defense

We solicited information from field and museum ornithologists on the birds that they consider odorous and/or unpalatable in order to identify species that may use chemicals to deter predators. Ninety-two ornithologists from the Americas and Eastern Europe responded to our survey. Eighty genera and 10 families representing 17 orders, primarily Procellariiformes, Falconiformes, Psittaciformes, Cuculiformes, Piciformes, and Passeriformes, were cited as containing malodorous or uniquely odorous birds. Two orders (Opisthocomiformes and Trogoniformes), five families (Procellariidae, Cuculidae, Bucconidae, Picidae, and Furnriidae), and one subfamily (Drepanidinae) were reported to us as either containing many odorous species or consisting primarily of them. Thirty genera and three families representing 13 orders, primarily Passeriformes, were reported to us as unpalatable. The birds cited in our survey and those previously reported as odorous and/or unpalatable are tabulated. Our survey and review point to a number of taxa that may use chemicals to deter predators, although we acknowledge that compounds imparting aversive or unique odors or flavors may arise for a variety of reasons, e.g., as dietary by-products.     

CATH--a hierarchic classification of protein domain structures

BACKGROUND: Protein evolution gives rise to families of structurally related proteins, within which sequence identities can be extremely low. As a result, structure-based classifications can be effective at identifying unanticipated relationships in known structures and in optimal cases function can also be assigned. The ever increasing number of known protein structures is too large to classify all proteins manually, therefore, automatic methods are needed for fast evaluation of protein structures. RESULTS: We present a semi-automatic procedure for deriving a novel hierarchical classification of protein domain structures (CATH). The four main levels of our classification are protein class (C), architecture (A), topology (T) and homologous superfamily (H). Class is the simplest level, and it essentially describes the secondary structure composition of each domain. In contrast, architecture summarises the shape revealed by the orientations of the secondary structure units, such as barrels and sandwiches. At the topology level, sequential connectivity is considered, such that members of the same architecture might have quite different topologies. When structures belonging to the same T-level have suitably high similarities combined with similar functions, the proteins are assumed to be evolutionarily related and put into the same homologous superfamily. CONCLUSIONS: Analysis of the structural families generated by CATH reveals the prominent features of protein structure space. We find that nearly a third of the homologous superfamilies (H-levels) belong to ten major T-levels, which we call superfolds, and furthermore that nearly two-thirds of these H-levels cluster into nine simple architectures. A database of well-characterised protein structure families, such as CATH, will facilitate the assignment of structure-function/evolution relationships to both known and newly determined protein structures.     

先进栅叠层的在线光谱分析法

量测平台的复杂性和光学原理上的局限性制约着测量系统的应用，直到真空紫外光谱反射仪的出现，这种状况才得到改变。     

Circulating angiotensin II and renal sodium handling in man: a dose-response study

1. Animal studies have shown that angiotensin II has a biphasic effect on urinary sodium excretion. To examine whether this is also true in man, we studied seven salt-replete male subjects in a single-blind placebo-controlled manner. 2. While undergoing maximum diuresis, subjects were infused with 0, 1, 2, 5 or 10 ng of angiotensin II min-1 kg-1 over 80 min. Subjects were studied while seated, and stood every 20 min for urine collection. 3. Angiotensin II produced a dose-dependent antidiuretic effect. The urine flow rate, in ml/min expressed as the change from baseline with increasing dose of angiotensin, was: +3.4 +/- 1.77, -1.26 +/- 0.49 (P < 0.05), -2.75 +/- 1.23 (P < 0.05), -4.21 +/- 0.82 (P < 0.05) and -6.51 +/- 1.07 (P < 0.01). 4. In contrast, the effect of angiotensin II on sodium excretion showed a flat dose-response curve beyond 5 ng min-1 kg-1. The urinary sodium excretion, in mumol/min expressed as the change from baseline with increasing dose of angiotensin, was: 9.5 +/- 21.2, -18.9 +/- 29.6, -37.0 +/- 11.6 (P < 0.05), -67.7 +/- 19.6 (P < 0.01) and -63.8 +/- 14.3 (P < 0.01). 5. The fractional distal reabsorption of sodium, determined by using the lithium clearance technique, showed a rise with all doses of angiotensin II used and reached statistical significance with the top two doses. 6. Unlike antidiuresis, antinatriuresis after graded doses of angiotensin II in human subjects showed a flat dose-response curve beyond 5 ng min-1 kg-1. Pressor doses of angiotensin II also have a significant effect on the distal tubule in promoting sodium reabsorption.