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PubMed1976

Identification of carcinogenic tannin isolated from Bracken fern (Pteridium aquilinum).

We attempted to isolate a carcinogenic substance from bracken fern (Pteridium aquilinum), a naturally occurring toxicant responsible for the production of chronic enzootic hematuria and urinary bladder cancer of cattle and carcinogenic for various target organs of several species. Hot methanol extracts of bracken fern were solubilized in water and extracted with chloroform followed by a mixture of n-butanol-butanone (1:1). That fraction was dried and triturated with ether-methanol (4:1), n-butanol, and finally absolute ethanol. The insoluble residue was dissolved in 10% aqueous methanol and passed through Dowex 1 OH-, Dowex 50 H+, or Dowex 1 OH- and then Dowex 50 H+ ion exchange resins. A condensed tannin, isolated from one ot the fractions, was identical to that isolated from bracken fern by the caffeine procedure used for the separation of tannins from other plant constituents. Three systems were used for bioassay; induction of bladder carcinoma by implantation of cholesterol pellets containing bracken fern fractions into the bladder lumens of mice; acute toxicity by ip injection of brachen fern fraction into mice; and growth inhibition of Escherichia coli. The following fractions induced significantly greater incidences of bladder carcinoma than did cholesterol pellets only: tannin, Dowex 50 H+, residue, n-butanol, and methanol. Tiliroside, a component of bracken fern fractions into the bladder lumens of mice; acute genic acid, and quercetin were not carcinogenic. Tannin was the most toxic (mean lethal dose: 0.16 mg/g) and carcinogenic. None of the carcinogenic fractions inhibited growth of E. coli.

Escherichia coli↗
PubMed1975

Observations on the male nucleus during fertilization in the fern Pteridium aquilinum.

Fertilization of eggs of Pteridium under controlled conditions has revealed that archegonia containing viable eggs require more than 30 min flooding before opening. Syngamy appears to take place by an engulfing action, and no evidence was found of a 'membrane-fusion' kind of conjugation. Although the gametic nucleus lacks a recognizable envelope, as soon as it comes into contact with the female cytoplasm an envelope is reconstituted from an opaque layer at the surface of its chromatin. This membrane also undergoes growth, the outer layer extending into the cytoplasm and surrounding spermatozoid mitochondria. The male envelope remains distinct from the female, and lacks evaginations and well defined pores. The male nucleus lies in irregular loops within a funnel, filled with egg cytoplasm, formed by the microtubular ribbon of the gamete. The mouth of the funnel is bordered by the multi-layered structure. Karyogamy is initiated at the anterior end of the male nucleus, the orifice connecting the 2 nuclei widening from about 0-1 to 2 mum in diameter during fusion. The contents of the male nucleus flow through the mouth of the funnel into the female, the chromatin relaxing locally, but retaining a rod-like form. The envelope of the male nucleus is probably resorbed at the site of junction. There is no evidence that it contributes significantly to the envelope of the zygotic nucleus.

Cell Nucleus↗
PubMed1978

A microtubule--nuclear envelope complex in the spermatozoid of Pteridium.

The microtubules on the outside of the nucleus of the mature spermatozoid of Pteridium form a complex with the envelope, and the perinuclear space is eliminated. These dissimilar components are held firmly together, possibly by hydrophobic bonding. The outer part of the chromatin is also attached to the inner boundary of the envelope, and pulls away when the envelope is detached.

Cell Nucleus↗
PubMed1977

Inhibition of carcinogenic effect of bracken fern (Pteridium aquilinum) by various chemicals.

The inhibitory effect of butylated hydroxyanosole (BHA), disulfiram, calcium chloride, and polyvinylpyrrolidone (PVP) on the intestinal and urothelial carcinogenicity of bracken fern (BF) was determined in albino rats. Of 10 groups of rats, one group received a normal diet, one received a BF-containing diet (one-third of diet by weight), four received a normal diet with one of the following supplements, and four received BF-containing diet with one of the following: BHA (5 mg/g diet); disulfiram (5 mg/g diet); PVP (50 mg/g diet); or calcium chloride (20 mg/g diet). At 12 months of the experiment, the following results were noted: in the BF-treated group, 30 rats (100%) exhibited intestinal tumors and 22 of 30 (73%) urinary bladder tumors. In the BF-BHA group, 15 of 20 rats (75%) showed intestinal tumors and 12 of 20 rats (60%) urinary bladder tumors. Of the 16 rats in the BF-disulfiram group, 12 (80%) had intestinal and 10 (62.5%) had urinary bladder tumors. In the BF-calcium chloride group, intestinal tumors arose in 16 of 23 rats (70%) and urinary bladder tumors in 4 of 23 rats (17%), while in the 28 BF-PVP rats, 26 (93%) exhibited tumors of the intestine and 5 (18%) tumors of the urinary bladder. Dietary BHA, disulfiram and calcium chloride decreased the incidence of intestinal tumors by about 25--30% (p less than 0.01). Similarly, PVP and calcium chloride inhibited BF-induced urinary bladder carcinogenesis by about 80% (p less than 0.001). No tumors were detected in groups receiving either normal diet or normal diet supplemented with BHA, disulfiram, calcium chloride or PVP.

Animals↗
PubMed1978

Carcinogenicity of boiling water extract of bracken, Pteridium aquilinum.

Carcinogenicity of an aqueous extract of bracken was studied in inbred strain ACI rats. In Experiment 1, Group 1 rats received a diet containing unprocessed dry bracken powder for 3 months, Group 2 received the boiling water extract of dry bracken as drinking water for 16 months, Group 3 received the cold water extract of dry bracken as drinking water for 16 months, and Group 4 received a diet containing the concentrated boiling water extract of dry bracken during the whole experimental period. Rats in Experiment 2 also received a diet containing the boiling water extract of dry bracken. A control group was fed a normal diet. Majority of the animals in Group 1 developed multiple ileal tumors, such as adenomas and adenocarcinomas. In Group 2, 6 of 11 rats which survived beyond 7 months developed tumors in either the ileum or urinary bladder, or in both. Rats in Group 3 had no tumor. In Group 4 and in Experiment 2, all the animals except 1 rat in Experiment 2 had urinary bladder tumor. Furthermore, almost all the rats in these groups had simultaneously ileal tumors. Based on these results, it may be assumed that the carcinogen in bracken is extractable in boiling water and is most probably also water-soluble.

Adenocarcinoma↗
PubMed2026

Co-option of stomata in the convergent evolution of fern nectaries.

Understanding the origin of new structures is a central goal of evolutionary biology. In many instances, novel phenotypes arise through heterotopy: the expression of a structure in a new location. Using bracken fern (Pteridium aquilinum) as a model, we combine genomics, transcriptomics and metabolomics to begin to explore the origin and developmental routes in the convergent evolution of ant-enticing nectaries. We observe that P. aquilinum does not exclusively express flowering plant 'nectary genes' during nectary development. Rather, this fern builds nectaries through co-option of stomata. Specifically, P. aquilinum heterotopically expresses canonical angiosperm stomatal regulatory genes, leading to stomatal development in novel positions along the petiole. These non-laminar stomata were co-opted for nectar secretion through the expression of putative sugar transport genes, forming secretory nectarostomata. This work provides two advances in our understanding of nectary evolution and the origin of complex structures. First, heterotopic expression of stomata, and later exaptation, represents one realized developmental mechanism for the evolution of nectar glands. Second, while there are many routes to nectary evolution, nectarostomata development is a repeatable path that has evolved in ferns and flowering plants, representing an impressive case of convergent evolution through the same developmental mechanism, despite over 400 million years of divergent history.

Plant Stomata↗
PubMed1978

Bovine enzootic haematuria in Queensland.

Bovine enzootic haematuria was diagnosed in Queensland in coastal areas in association with bracken fern (Pteridium esculentum) on 3 properties or with mulga fern or rock fern (Cheilanthes sieberi) on 4 properties, and in inland areas in association with C. sieberi on 3 properties. In the absence of bracken fern, long-term ingestion of C. sieberi is suggested as a cause of bovine enzootic haematuria. Haemangiomas, haemangiosarcomas, transitional cell carcinomas, papillomas, fibromas and an adenoma were detected in the urinary bladders of 19 affected cattle and were accompanied by chronic cystitis.

Animals↗