Opioid-binding protein (OBCAM) is rich in β-sheets

Based on circular dichroism (CD) and the sequence-predictive method, the opioid-binding cell adhesion molecule (OBCAM) consisted of one half -sheets and one fourth -helices. This is consistent with significant sequence homology of the protein to several members of the immunoglobulin (Ig) superfamily, particularly cell adhesion molecules, which are rich in -sheets. Hydropathy analysis suggests that hydrophobic and hydrophilic regions were evenly distributed along the sequence, but the NH₂- and COOH-termini were hydrophobic. Hydrophobic moments and Fourier-transform amphipathic analyses further suggest that residues 23–30 and 83–93 were amphiphathie -sheets. The overall conformation of OBCAM was unaltered by adding linoleic acid, which is required for opioid ligand binding.     

β-II conformation of all-β proteins can be distinguished from unordered form by circular dichroism

The CD spectrum of certain all-β globular proteins resembles that of unfolded proteins with a characteristic negative band around 200 nm. The conformation of this class is tentatively termed β-II, which had two features that were absent for unfolded proteins. First, β-II proteins usually had CD bands due to aromatic side groups in the near-ultraviolet region. Second, the CD intensities both in the far- and in the near-uv region of these compact and rigid proteins usually showed a sharp transition upon thermal denaturation, whereas those of an unordered form changed linearly with rising temperature.     

云南西双版纳兰科十新种

1.豹斑石豆兰 新种 图1:5—6Bulbophyllum colomaculosum Tsi et S. C. Chen, sp. nov.Species nova B. obrieniano Rolfe proxima, a quo differt petalis margine dentatis.Herba epiphytica. pseudobulbi aggregati ovati, ca. 4 cm longi, medio 1.5—1.8 cm lati,     

Conformation and activity ofPhaseolus coccineus var. rubronanus lectin

The conformation of native and denaturedPhaseolus coccineus var. rubronanus lectin was studied by circular dichroism (CD) and correlated to the hemagglutinating activity. The far-UV CD spectrum at 25°C showed a broad, negative band around 223 nm and a positive one at 196 nm. CD data analysis of the lectin indicated a -sheet-rich protein. At high temperatures, the spectrum was blue-shifted with increasing magnitude; these changes correlated well with the loss of the activity. The conformation of lectin betweenpH 2 and 10 remained essentially unchanged. AtpH 13 the CD spectrum resembled that of unordered form with a negative band near 200 nm and the activity was completely lost. The denatured lectin in 6 M guanidine hydrochloride would be renatured upon diluting the denaturant to 0.75 M; the changes in CD spectrum again correlated well with the loss of the activity. The effect of sodium dodecyl sulfate on the lectin was drastic; it sharply increased thea-helix at the expense of the -sheet and reduced the activity; the changes reached a plateau above 20 mM surfactant.     

Optical rotatory dispersion and circular dichroism of silver(I):Polyribonucleotide complexes

Optical rotatory dispersion (ORD) and circular dichroism (CD) spectra of single- and multistranded polyribonucleotides undergo extensive changes on binding of the silver ion. These changes are consistent with the proposition that Ag(I) binds to the heterocyclic bases and not to the phosphate groups of polynucleotides. ORD and CD of silver complexes of poly(A)·poly(U) and double-helical rice dwarf viral RNA display negative Cotton effects when there is more than one Ag(I) per two nucleotide residues in solution. These observations suggest a significant distortion of the double-helical conformation as a result of Ag(I) binding. Silver(I) binding sites of pyrimidine polynucleotides are apparently saturated when there is one Ag(I) per two nucleotide residues and those of purine polynucleotides at one Ag(I) per nucleotide in solution. These data are consistent with the supposition that some Ag(I) binding sites exist on the pyrimidine ring and additional sites on the imidazole ring of polynucleotides. The sedimentation coefficient of poly(A) increases by severalfold when one Ag(I) is present per nucleotide residue. Silver(I) may introduce intra- and interstrand cross-links (through bidentate chelates) in single-stranded polynucleotides, resulting in structures with high sedimentation coefficients. Among the polynucleotides studied, poly(U) was an exception. Silver(I) did not affect the optical properties (absorbance, ORD, and CD) of poly(U) at neutral pH.     

Effects of postexercise supplementation of chicken essence on the elimination of exercise-induced plasma lactate and ammonia

We investigated the effects of chicken essence (CE) supplementation on exercise-induced changes of lactate and ammonia during recovery. In this randomized, double blind, crossover study, twelve healthy subjects performed a single bout of exercise to exhaustion, and then consumed either a placebo or CE within 5-min of the exercise cessation. Blood samples were collected before exercise, at exhaustion (0 minute), and 20, 40, 60, and 120 minutes, respectively during the recovery period. There were no differences in plasma glucose, creatine kinase, or heart rate responses between treatments. The exercise exhaustion significantly increased the levels of lactate and ammonia, and both measured values gradually declined during the recovery period. Ammonia levels at 40, 60, and 120 min. of the recovery period were observed lower significantly in the CE group, as compared to those in the placebo group. Additionally, lactate concentrations at 60 and 120 min were lower in the CE group, as compared to those in the placebo group. In conclusion, the main finding of this study was that CE supplementation after exercise reduces plasma lactate and ammonia levels. The results indicated that CE supplementation after an exhaustive exercise could enhance physiological recovery in humans.     

Induced optical activity of chondroitin sulfate c–acridine orange complexes

Chondroitin sulfate C (CSC) and acrdiine orange (AO) formed two types of complexes at neutral pH, depending upon the order of mixing. The induced optical activity of AO was much more pronounced when the polysaccharide was added to dye than the dye to polymer (final concentration of dye was 5 × 10⁵M). The difference in aggregation of the dye molecules is believed to be responsible for the observed peculiarities. The Cotton effects of the CSC-to-dye solution displayed a sharp inversion near 59°C. and the profile at 76°C. was almost a mirror image of that at room temperature. At pH 1.3, however, the order of mixing became unimportant, suggesting that the carboxylate on the polysaccharide way involved more intimately than were sulfates in the peculiarities of the Cotton effects.     

Miscellaneous Notes on Orchids in Xishuangbanna of Yunnan,China

Xishuangbanna, lying between 99°56´ and 101°50´E longitude and 21°08´ and 22°36´ N latitude of southern Yunnan, is located on the northern fringe of the tropics. Its orchid flora is very rich but little known to the outside world. From 1980 to 1992, the authors tripped seven times to that region collecting and studying orchids there. As a result, 335 species and two varieties belonging to 96 genera were identified as indigenous to Xishuangbanna region. Among them, two genera (Pennilabium J. J. Sm. & Parapteroceras Averyanov), 50 species are new to China, 190 species new to this region, and 21 species and one variety are endemic to Xishuangbanna. It is interesting to note that both genera and species native to Xishuangbanna are more than those in Hainan and comparable to those in Taiwan, though the collection in this region is not complete.     

Eria mêdogensis,a Probably Peloric Form of Eria Coronaria,with a Discussion on Peloria in Orchidaceae

Eria mêdogensis S. C. Chen et Tsi was recently found in southeastern Tibet, several specimens of which have been collected by various botanists since 1980. This is a “normal” entity with its habit very similar to that of Eria coronaria, from which it differs by having a regular perianth and longer bracts. We think it probable that this new entity is a peloric form of Eria coronaria. Peloria (or pelory) is a type of floral abnormality, which is found in many zygomorphicflowered taxa. It was first detected by Linnaeus (1744) in Linaria vulgaris, and then by others in Labiatae, Orchidaceae, etc. However, it is still an open question how to explain it theoretically and how to treat it taxonomically. In Orchidaceae, so far as our knowledge is concerned, peloria has been encountered in no less than 21 genera. In most cases, peloric flowers are found sporadically on an occassional plant, as seen in Cypripedium reginae and Eria oblitterata. Sometimes, however, peloric form may occur coexisting with normal-flowered form in one and the same species, as seen in Dendrobium tetrodon and Epipogium roseum. They are both abnormally peloric forms. It would not result in naming or renaming a plant taxonomically, whether the appearance of abnormally regular flowers on a normal-flowered inflorescence, or of abnormal-flowered individuals in normal-flowered species. In Phragmipedium lindenii, however, the case is different. It is quite “normal” and even of wider distribution than its nonpeloric allies P. wallisii and P. caudatum, from which it has once been considered to be derived. This is a normally peloric form. Whether it is a reversal or not, the appearance of a “normally” peloric taxon may be taken for a leap in the process of evolution. Taxonomically, we had better treat it as a separate species, especially when its origin is uncertain. For example, the entity just mentioned had been treated as a peloric va riety of Phragmipedium caudatum (var. lindenii) until 1975, when Dressler & Williams recognized it as an independent species based on the fact that its nonpeloric flowers occassionally found in a peloric population in Jungurahua of Ecuador are dissimilar in lip to those in P. caudatum. Garay (1979) considered it to be a peloric form of P. wallisii but maintained it at the specific level. This is indeed a good example of taxonomic treatment of normally peloric form. On the other hand, however, most of the regular-flowered entities in Orchidaceae are not peloric but rather primitive forms, such as Neuwiedia, Apostasia and Thelymitra, of which no less than 50 species have been reported since the eighteen century. They have never been regarded as peloric forms. Unfortunately, this has been neglected by some botanists. For instance, a hypothetically primitive orchid flower designed by Pijl & Dodson (1966) has a distinctly specialized lip with a short spur. In fact, in addition to the aforementioned genera we have some more examples of normally regular-flowered orchids. Among them Archineottia is the most interesting. This is a genus of four species, two of which are regular-flowered. Of special interest is that in this genus and its ally, Neottia, one can find all steps of column evolution from a simple form with stamen and style not fully united to a most complicated form in which they have well fused. Archineottia has a very primitive column, on which neither rostellum nor clinandrium is found but a terminal and undifferentiated stigma (Fig.2: 2, 4, 6, 8). In addition, there exists on the back of the column a thick ridge with its upper end joining the filament with which it is of same texture. It is obviously the lower part of the filament which has been adnate to the style (column). In Neottia, however, the column is much more advanced and very typical among the family. It has a very large rostellum and most complicated stigma structure (Fig. 10, 12, 14, 16, 18). One of the most interesting examples is Neottia acuminata, in which the stigma even becomes lamellate and almost backwards clasps the erect rostellum, but the perianth is more or less regular with its lip entire and somewhat similar to, but shorter and wider than, the petals. In these two genera there are altogether three species, namely Archineottia gaudissartii, A microglottis and Neottia acuminata, possessing regular or nearly regular perianth (Fig. 2: 1, 3, 17). They are obviously not peloric forms. We can not imagine, indeed, that a complicated form like Neottia acuminata or its allies would degenerate step by step into a simple form, and finally into a peloric form. Archineottia belongs to the subtribe Listerinae, which is closely related to Limodorinae, a rather primitivs subtribe with some genera possessing single pollen grain, relatively few and long chromosomes and monocotyledonous habit. Apparently, there is nothing surprising in the occurrence of some normally regular-flowered taxa, such as Archineottia, Diplandrorchis, Tangtsinia and Sinorchis, in these two primitive subtribes. Another instance is Aceratorchis, a genus formerly included in Orchis, from which it is distinguished by the entire lip which is more or less similar to the petals. Strictly speaking, however, its flowers are not truly regular. Two species have been described in this genus, but they were recently considered as conspecific. Aceratorchis tschiliensis is widely distributed from Hebei through Qinghai and Sichuan to northwestern Yunnan. It is cross-pollinated and produces seeds efficiently. All these indicate its normally primitive taxon, instead of peloria. It may be noted here that Asia is rich in members of Orchidioideae, as well as its primitive representatives. The occurrence of a normally regular-flowered form in Asia, whether representing primitive form of Orchis or Orchidioideae, is imaginable. In Orchidaceae, as mentioned above, regular flowers are not only found in some primitive taxa and peloric forms, but also in a few advanced groups. For example, a close investigation by the senior author (Chen 1979) on Satyrium ciliatum revealed that this species has hermaphrodite, staminate and pistallate forms, for which no less than nine names have been published. The flowers of its pistallate form are almost regular, in which nothing is found but three similar petals and an elongate style with three stigmatic lobes at its top (Fig. 2: 19). It is interesting to note that floral reversions in Orchidaceae are not always in connection with peloria. For example, Epidendrum triandrum of North America represents another kind of reversion. It is a reversal to abnormal polymery of stamens and not to abnormal regularity of perianth. Like Phragmipedium lindenii, it is also hereditary. We may give it a new name “Polyandrism” or something else, but, in fact, there is no essential distinction of this kind of reversion from peloria. It deserves mentioning that most of the regular-flowered entities, including primitive, advanced and peloric ones, occur in Asia and Australasia, where the Orchidaceae may have originated as pointed out by some botanists. We have good reason to verify the primitiveness and normality of many regular-flowered entities, but there exists no sufficient evidence for the impossible existances of normally regular-flowered species in those like Dendrobium, Eria, Lecanorchis, etc. For instance, Lecanorchis javanica, Dendrobium atavus and the new species described here are considered to be peloric forms, but it is only a conjecture, for no reason can be given for it. It is not impossible that some so-called peloric forms may prove to be truly primitive ones in the future. Of course, a closer investigation is needed. Summarizing the above, we may come to the following conclusions: 1. Regular or nearly regular perianth is a normal characteristic of orchids. It is chiefly found in some primitive taxa and sometimes also in certain peloric forms and advanced groups. Regular-flowered entities may not necessarily be peloric forms. 2. There exist two different types of peloria in Orchidaceae. One is abnormal form, with its peloric flowers appearing at random. The other is “normal” form, with its individuals all possessing peloric flowers. The latter is inheritable and can produce seeds efficiently, It would be best to treat it as an independent species taxonomically, especially when its origin is uncertain. 3. Although peloria has been considered to he a reversal as a whole, conditions vary from plant to plant. Some peloric forms have petal-like lip, and others have labellum-like petals. Sometimes the same plant produces different kinds of peloric flowers in different years, sometimes peloric flowers do not reappear upon the same plant. A few species can produce both peloric and normal individuals, but others produce peloric forms only. Peloria is in fact a term only used to cover the phase in which lip becomes similar to the petals. It is never all-embracing. We recognize the existance of peloria in Orchidaceae, but great care must be taken to distinguish truly peloric form from normally primitive one. It must be admitted that what causes peloria and even what is peloria are still problems awaiting solution. Acknowledgments: Our heartfelt thanks are due to Dr. Leslie A. Garay, Curator of the Orchid Herbarium of Oakes Ames, Botanical Museum of Harvard University, for his valuable suggestions during the preparation of this paper. We are also indebted to the artists, Mrs. Chunrung Liu and Mr. Chao-zhen Ji of our department, for their preparing the fine drawings.     

中国兰科两新种

本文发表了兰科两新种, 即文山石仙桃Pholidota wenshanica S.C.Chen etTsi;细茎毛兰Eria gracilicculis S.C.Chen et Tsi。